Written by Athea Bianca Geonigo

Reviewed by Dr. Reuben J C. Los Baños, Ph.D.

The study of the body’s structure is known as anatomy. It is a field of study that looks into the bones, organs, tissues, and cells found in both humans and animals. 

The average human body has 37.2 trillion cells, of which there are currently over 200 known varieties. There are about 640 identified muscles in the human body. The number may vary by how they are categorized. 

The 10 Body Systems: 

To better explain how body parts work, anatomy experts (or anatomists) often divide the body into ten systems. 

• Skeletal system is your body’s framework supporting your body. It creates blood cells, gives your body form, permits movement, shields your organs, and stores minerals. (bones, cartilage, and joints) 

• Muscular system consists of muscle fibers, which are specialized cells. They are in charge of controlling your movement and are affixed to your bones, internal organs, and blood vessels. (muscle) 

• Nervous system transmits information from your brain to your body. (brain and nerves) 

• Respiratory system absorbs oxygen from the air we breathe and releases carbon dioxide that isn’t needed. (lungs and trachea) 

• Cardiovascular system provides nutrition and oxygen to your body’s organs, enabling them to perform their functions. (heart, arteries, veins, and blood) 

• Lymphatic system balances your bodily fluid levels and protects your body from illnesses. (bone marrow, thymus, lymph nodes, and spleen) 
• Endocrine system produces hormones and releases them straight into the bloodstream, allowing them to reach all of your body’s tissues and organs. (thyroid, pituitary, and adrenal glands) 

• Reproductive system produces hormones, which are in charge of your menstruation, sexual activity, and fertility. (uterus, ovaries, penis, and testicles) 462 

• Digestive system breaks down the meals you eat into their most basic forms, such as fatty acids (which make up lipids), glucose (sugars), or amino acids (which make up protein). (mouth, esophagus, stomach, and intestines) 
• Urinary system produces urine as a waste byproduct and filters blood. (kidneys and bladder) 

Medical practitioners must use anatomical knowledge in their practice. Accurate diagnosis, effective treatment, and surgical skills depend on it. 

Any branch of medical science requires a solid understanding of anatomy before practicing. We must identify the body’s dysfunctional organs. Then, we should link symptoms to chronic illness. This will help in making the right diagnosis. 

In clinical settings, medical practitioners use their anatomical knowledge. They interpret imaging data, identify problems, and communicate with patients and other providers. Surgeons, in particular, rely on their anatomical knowledge for complex surgeries. It helps them lower risks and improve patient outcomes. 

Medical Research 

It is essential for medical research and development and clinical practice. Anatomical structure analysis is often used in research investigations to understand illness mechanisms better, create new remedies, and progress medical technology. Its contribution to research is essential for advancing change and advancement in the medical industry. Significant discoveries and medical progress would be restricted without a comprehensive comprehension of anatomy. 

Clinical Application 

In the course of their work, doctors deal with a wide range of illnesses and injuries. Doctors who possess a firm grasp of anatomy are better equipped to do comprehensive physical examinations, spot anomalies, and diagnose the underlying cause of symptoms. An expert in anatomy, for example, can locate a tumor or a broken bone with great accuracy, enabling the development of effective treatment strategies. 

Surgical Expertise 

Anatomy is crucial knowledge for those who want to become surgeons. During surgery, tissues and organs must be precisely manipulated; any mistake could have serious repercussions for the patient. Surgeons can safely navigate complex anatomical structures, plan procedures with greater efficiency, and reduce procedural risks when they possess a solid foundation in anatomy. 

Understanding Physiology and Pathology 

The three are closely related concepts. Whereas pathology studies the alterations brought about by disease processes, physiology investigates the roles of various anatomical components. Understanding the complexity of physiology and pathology becomes much more difficult in the absence of a solid anatomical foundation. 

Furthermore, anatomy serves purposes beyond the realm of medicine. Medical researchers seek to improve medicine. They use advanced treatments and study anatomy to better understand disorders. Knowledge of anatomy helps with diagnostic imaging, like MRIs and X-rays. It allows doctors to find issues and create effective treatment plans. 

What is the importance of learning the language of anatomy? 

Since anatomy forms the foundation for medical practice and other health-related courses, students majoring in health sciences must possess a solid grasp of fundamental anatomical terminology. With cutting-edge imaging methods or a clinical examination, a professional can better comprehend a patient’s condition thanks to their anatomy expertise. 

Understanding anatomical words and placing them in their proper context—providing insight into how the human body works in both health and disease—is just as important as learning the terms themselves. Health practitioners can communicate accurately with one another domestically and globally when they precisely employ anatomical terminology. 

It is impossible to talk about or precisely document aberrant joint or muscle function, changes in the organs’ positions, or the precise location of tumors or edema without anatomical terminology. Thus, mastering solid concepts and anatomical language should lead to the capacity to interpret a clinical observation accurately. 

What language does the word “Anatomy” come from? 

The Greek language is where the word “anatomy” originated. The word comes from the Greek word “anatome” (ἀνατoμή), which means “dissection” or “cutting up.” It is a compound word made up of the words “ana-,” which means “up” or “apart,” and “tome,” which means “cutting.” 

This reflects the ancient practice of dissecting bodies to study their structure, which forms the basis of the field of anatomy. 

Why is it important that we have a universal language of anatomy? 

The significance of using universal language when talking about movements, anatomical planes, and anatomical position so that the patient or client and the expert may both comprehend and communicate with ease. 

This makes it less likely that people will misinterpret or confuse one another. The capacity to understand the structure and placement of the body’s position and planes is aided by the universal language of anatomical movement. 

Over the ages, anatomy has developed a uniform system of technical words to annotate thousands of body parts. Gaspard Bauhin (1560–1624) introduced Latin anatomical nomenclature in the sixteenth century. Without his invention, many more words would be required to refer to different body parts. Rather than creating a word to describe every structure and component, the nomenclature may clearly and alone specify each unique structure. 

Who was the first person to study anatomy? 

Herophilus, a physician from Alexandria who is frequently referred to as “The Father of Anatomy”, was born in Chalcedon, Bithynia, around 335 BC and passed away in 280 BC. Herophilus was a pioneer of public dissections on human cadavers. 

He was a Greek physician who investigated the nerve trunks, dura mater sinuses, and brain ventricles. He also checked the pancreas, liver, salivary glands, eyes, and both sexes’ sexual organs. He gave the prostate and duodenum names. 

Herophilus studied under Hippocrates, who promoted the healing properties of medications, dietetics, and gymnastics while emphasizing the balancing of bodily fluids. He was the first to use a water clock to measure the pulse. 

Early History and Other Notable Anatomists 

In 300 BC, an anatomy school was established in Alexandria, Egypt. Alessandra Giliani was the first woman to be documented as practicing anatomy and pathology in the 1300s, but there were probably many more before her. Women have historically practiced medicine and midwifery. 

There have also been artists among anatomists. Leonardo Da Vinci created incredible works of art that brought together science and the arts to help illustrate what was within the body. Another Italian artist and anatomist was Anna Morandi Manzolini. She worked in her home laboratory in the 1700s, lecturing, writing about organs, and making intricate wax models. 

What is the best way to understand anatomy? 

Visualization and active learning strategies are among the best ways to learn anatomy. Participate in the content by actively reading lecture notes or textbooks rather than just passively reading them. To improve your comprehension, make use of visual aids like interactive applications, illustrations, and anatomical models. 

Here are some effective methods for understanding Anatomy: 

• Anatomical Terminologies and Knowing the Basics. Start your study by becoming familiar with the fundamental ideas and terms related to anatomy. Before moving on to more complicated subjects, lay a solid foundation by becoming familiar with the body systems, important structures, and anatomical terminology. 

• Visual Materials and Aids. With the use of several visual aids, learn anatomy. Visual aids, such as atlases, diagrams, 2D pictures, 3D materials, and movies, can significantly alter an educational process. 

• Active Recall. Use the proven study method of active recall. It is better than just repeating things. It helps you actively retrieve newly learned material by stimulating your brain. This not only makes studying less interesting, but it also helps you retain the material better for your next exam or quiz. 

• Quizzes and Testing Your Knowledge. Test your knowledge with a variety of quizzes to put what you’ve learned into practice. Tests are a useful tool since they help you remember all you’ve studied. Additionally, they assist you in determining what areas you still need to fill in while studying anatomy and how well-versed you are in the subject. 

• Study in Groups and Peer Teaching. Studying with others may be enjoyable and very gratifying, in addition to being a great method to talk about the structures, exchange thoughts, and quiz one another. Furthermore, having a sounding board for suggestions can either improve your retention of the material or, on the other hand, highlight the areas that require more focus. Some claim that studying in groups even increases their motivation. 

• Find out your Learning Style. Try out as many various approaches and strategies as you can until you find one that works best for you and quickens your heartbeat. Sometimes, the finest results come from combining completely different study strategies. 
• Learn to love Anatomy. The best approach to quickly learning anatomy is to develop a passion for the subject. The way anatomy magically connects all the knowledge you’ve acquired will become apparent to you if you try to make connections between every piece of knowledge. Once you understand that, everything connects. 

It is normally taught over a specified amount of time, which can be anywhere from a few weeks to a whole semester, in a formal academic context like medical school or a comparable program. 

When studying independently, there can be a large range in how long it takes. The amount of time you can commit to studying, your past biology and related course knowledge, and the resources available to you will all play a role. Depending on how far you want to go with your studies, self- study may take several months to a year or longer. 

How can understanding anatomy can help you with your daily life? 

Understanding anatomy is crucial for a variety of reasons. It aids in your comprehension of the human body and how your own works. It also helps you comprehend why illnesses occur and what you can do to prevent them. Gaining knowledge about it will also enable us to better understand how our surroundings impact our health and how we can alter it for the better. 

Beyond the specific organs and systems, it’s critical to comprehend how the many components of the human body function as a whole. Human health is influenced by various systems, including the respiratory, lymphatic, and circulatory systems, and these interactions can be beneficial or detrimental. You can choose the best course of action for each patient and their unique set of symptoms by knowing how the systems work together. 

An understanding of anatomy and physiology will provide you with the fundamental knowledge needed to make the right choices and deliver precise, high-quality care. 

Conclusion 

In its broadest sense, anatomy is the study that examines the structure and evolution of living things. Since knowledge of human anatomy is essential to comprehending human physiology and pathological processes, it becomes required reading for all courses in the health field. 

It includes studying the anatomy of the human body and is crucial to medical education. It aids medical students in gaining a thorough understanding of the body’s anatomy, which serves as the foundation for illness diagnosis and treatment. 

References 

Stanford, K., Rutland, S., Sturrock, C. J., & Rutland, C. S. (2020). The importance of anatomy. 

Frontiers for Young Minds, 8. https://doi.org/10.3389/frym.2020.546763 

Khan, I. A., & Singh, Y. (2023). The crucial role of anatomy in shaping competent medical doctors. 

ResearchGate. https://www.researchgate.net/publication/374337716_The_Crucial_Role_of_Anatomy_in _

Body Systems, Functions, and organs – LabCE.com, Laboratory Continuing Education. (n.d.). https://www.labce.com/spg538250_body_systems_functions_and_organs.aspx?srsltid=A fmBOoomF8EQJyHSFCysll8QLuRzphsf0E16mcmoB8u56g0SFuf7ojdM 

Gonçalves, G. R., Cabral, R. H., & Grecco, L. H. (2020). The importance of Anatomical Terminology employment in health sciences. Revista Brasileira De Educação Médica, 44(4). https://doi.org/10.1590/1981-5271v44.4-20200180.ing 

Brazier, Y. (2023, April 25). Anatomy: A brief introduction. https://www.medicalnewstoday.com/articles/248743 

Hill, R. (2024, April 12). Top Tips for Learning Anatomy – The Medic Portal. The Medic Portal. https://www.themedicportal.com/blog/top-tips-for-learning- anatomy/#:~:text=One%20of%20the%20most%20effective,apps%20to%20enhance%20 your%20understanding. 

Next, A. (n.d.). %s | Anatomy.app | Learn anatomy | 3D models, articles, and quizzes. https://anatomy.app/blog/how-to-learn-anatomy-fast 

TheStudentMedic. (2024, May 6). 5 Tips for Learning Anatomy: Techniques and Strategies for success. TheStudentMedic. https://www.thestudentmedic.com/post/5-tips-for-learning- anatomy-techniques-and-strategies-for-success 

Lumen Learning & OpenStax. (n.d.). Anatomical Terminology | Anatomy and Physiology i. https://courses.lumenlearning.com/suny-ap1/chapter/anatomical- terminology/#:~:text=By%20using%20precise%20anatomical%20terminology,roots%2C %20prefixes%2C%20and%20suffixes. 

The Editors of Encyclopaedia Britannica. (1998, July 20). HeroPhilus | Biography, study of anatomy & Facts. Encyclopedia Britannica. https://www.britannica.com/biography/Herophilus 

Rhoads, J. (2024, February 14). The importance of an anatomy and physiology foundation. Corexcel. https://www.corexcel.com/blog/2017/04/17/the-importance-of-an-anatomy- and-physiology-foundation/ 

GS Group & GS Medical College & Hospital. (2023b, August 2). The significance of anatomy as a core subject in medical training and knowledge. GS Medical College & Hospital. https://gsmedicalcollege.in/the-significance-of-anatomy-as-a-core-subject-in-medical-training- and knowledge.php#:~:text=Anatomy%2C%20involving%20the%20study%20of,for%20diagnosing %20and%20treating%20diseases. 

Written by Jarixa Balbuena

Reviewed by Reuben J C. Los Baños, Ph.D.

What is the structure of the respiratory system? The respiratory system is a network of different organs that help you breathe. These organs work together to help with gas exchange, necessary for a functional body. It is also composed of structures that connect the organs. The respiratory system is also surrounded by layers of tissues and blood vessels. These structures help protect and support the respiratory system. 

The general function of the respiratory system is to bring oxygen to the body. Along with this process, waste products like carbon dioxide are also expelled. This complex process happens whenever you breathe in and out. Other functions of the respiratory system include: 

• Gas exchange. This refers to the swapping of oxygen and carbon dioxide in the bloodstream. The lungs exchange gases. This way, it delivers oxygen to the body while eliminating waste carbon dioxide. 

• Air filtration. The mucus and cilia in the respiratory tract filter out dust and particles from the air. This ensures that the air we breathe in is free from pathogens and is safe for circulation. 

• Sound production. The larynx or voice box contains the vocal cords that vibrate with air. Respiration enables air to pass along the larynx. The vibration of the vocal cords produces speech and vocal sounds. 

• Olfaction. When we breathe air in, tiny odor particles float up to our nose. Special smell sensors (olfactory nerves) in the nose send a message to your brain. The brain interprets this signal, telling us what the smell is like. 

• Regulation of blood pH. Excess carbon dioxide levels in the blood make it acidic. Through respiration, carbon dioxide exits the body. This mechanism helps regulate blood pH back to safe pH levels for the body. 

A variety of organs, muscles, and tissues make up the respiratory system. We can classify the structures of the system based on its functions and locations. Based on functionality, the system has two components: 

• The respiratory system conducts air through a series of passages. This pathway starts with the nasal cavities and pharynx. It continues down the trachea, bronchi, and then the bronchioles and terminal bronchioles. These structures make up the conducting component of the system. 

• The second component of the system is the respiratory component. This part is where gas exchange occurs firsthand. The respiratory bronchioles, ducts, and alveoli make up this part. 

The system also divides into upper and lower regions based on location. 

• The upper respiratory tract is the first part of our breathing journey. It starts with the nose and mouth where air comes in. After that, air travels through the nasal cavity, sinuses, and larynx. These structures help moisten, warm, and filter air before it proceeds inside the body. 

• The lower respiratory tract includes the trachea, bronchi, and lungs. These organs all work together to take the air to the alveoli in the lungs. It is in the alveoli where gas exchange occurs. 

The system also has a group of muscles that aid in the respiration process. These groups of muscles are the muscles of respiration. The diaphragm, intercostal muscles, and some accessory muscles make up this muscle group. They control the movement of air in and out of the body as you breathe. 

• The diaphragm is a dome-shaped muscle below the lungs. It separates the chest cavity from the abdominal cavity. When it flattens and expands the chest cavity, it creates a vacuum. This vacuum pulls air into the lungs in a process called inhalation. As the diaphragm relaxes, the chest cavity also relaxes. The lungs push the air out from the body, known as exhalation. 

• Intercostal muscles are present between the ribs. These muscles lift the ribs during inhalation to accommodate the lung’s expansion. When the lungs relax during exhalation, these muscles help pull the ribcage downward. 

• Accessory muscles also aid in speech, singing, and breathing. The sternocleidomastoid in the neck helps during heavy breathing. This muscle also aids in forced exhalation such as in coughing or singing. 

What is the respiratory lining of the nasal cavity? 

The epithelium throughout most of the respiratory system is not a passive barrier. It plays a crucial role by being the first line of defense against germs and infections. It also helps keep the airways moist and prevent irritation. 

There are various histological layers within the respiratory system. 

Specialized linings and cells take charge of the respiratory tract. These cells ensure that the inhaled air is clean and safe. Some of these cells help us smell. Others ensure a healthy cell layer in the respiratory tract. Some cells aid in the functioning of the organs in the system. 

Pseudostratified columnar epithelium lines most of the respiratory tract. But, they are not found in the larynx and pharynx. This special lining acts like a double shield. It blocks germs and dust from entering. It also helps prevent infections and irritation. This epithelium has three types of cells present: 

• Goblet cells are responsible for mucus production. Mucus helps trap particles and pathogens. It also keeps a healthy level of moisture in the airways. This moisture prevents the respiratory tract from drying out and irritation. 

• Basal cells undergo constant division to replace other epithelial cells lining the airways. This ensures a healthy and functional layer of cells throughout the respiratory tract. 

• Cilia are millions of tiny hairs on the surface of respiratory airways. They beat in a constant wave-like motion. The rhythmic beating of cilia propels mucus and trapped particles towards the throat. This allows you to cough it out or swallow it. The mucus that reaches your stomach gets broken down. 

Alveolar epithelial cells (AECs) line the tiny, spongy air sacs throughout your lungs. These air sacs are the alveoli. The cells in this area take part in the easy diffusion of gases for gas exchange. There are two types of AECs: 

• Alveolar Epithelial Cell I (AEC I) covers the majority of the alveolar surface. These cells are vital in the gas exchange process around the alveoli. 

• Alveolar Epithelial Cell II (AEC II) contributes to lung defense. This alveolar epithelial cell is also subject to further studies. They also have regenerative potential. 

What is the main function of the respiratory epithelium in the nasal cavity? 

The respiratory epithelium acts as a guardian to the rest of the respiratory system. It filters, warms, and humidifies the air we breathe in before it reaches the lungs. It is important to warm the air we breathe in. 

The lungs work best when they receive air that is close to our body temperature. Cold air may cause our airways to constrict. Warming the air before gas exchange prevents this constriction. This ensures efficient oxygen delivery to the cells of the body. 

Warm and moist air prevents irritation to the delicate tissues lining the airways. The tissues moisten and warm the air to protect the respiratory linings from damage. The vasculature of the alveoli and capillaries is extra delicate. Warming the air lessens the likelihood of causing harm to these structures. 

The respiratory epithelium also relies on mucus and cilia to trap particles. This mucociliary clearance system is most effective at a specific consistency. Cold air dries out the mucus, making it thicker and stickier. This hinders the cilia’s ability to propel particles. 

These functions of the respiratory epithelium contribute to respiratory health. 

What is the histology of the olfactory mucosa? 

The olfactory mucosa has a specialized histological structure to detect smells. It is on the roof of the nasal cavity. This structure covers the superior nasal concha and the upper part of the nasal septum. The olfactory mucosa has two histological components: 

The olfactory epithelium is a pseudostratified columnar epithelium. It has three main cell types: 

• Olfactory Receptor Neurons (ORNs) are bipolar neurons. They extend to the epithelial surface and end in the cilia. These cilia contain receptors for smell molecules. 

• Supporting (Sustentacular) cells are columnar cells. They provide structural support, nourishment, and insulation to the olfactory receptor neurons. They also help detoxify harmful substances through their metabolic activities. 

• Basal cells are stem cells located at the base of the epithelium. They can differentiate into new olfactory receptor neurons or supporting cells. These cells maintain the regenerative capacity of the olfactory epithelium. 

The lamina propria is a connective tissue beneath the olfactory epithelium. It contains the following structures: 

• Bowman’s Glands. These glands produce mucus that is secreted onto the olfactory epithelium. The secreted mucus helps pick up the smell. It also flushes out old smells to detect new smells. 

• Blood Vessels and Nerves. The lamina propria is a vascularized structure. The blood vessels provide nutrients and support to the epithelial cells. 

This histological structure enables the olfactory mucosa to detect and process odorant molecules. This mechanism plays a crucial role in the sense of smell. 

What are the histological layers of the trachea? 

The trachea is also known as the windpipe. This tubular structure provides a passageway for air to enter and exit the lungs. The histological layers of the trachea are: 

• Mucosa. The mucosa is the innermost lining of the trachea. It has pseudostratified ciliated columnar epithelium. This layer also contains goblet cells and the lamina propria. 

• Submucosa. This layer has a dense connective tissue compared to the lamina propria. It contains glands that produce a mixture of serous (watery) and mucous (viscous) fluids. These secretions help to moisten the air and trap particles to protect the airways. 

• Cartilaginous layer. The trachea has C-shaped rings of hyaline cartilage. The cartilage rings provide structural support. They prevent the trachea from collapsing while allowing flexibility. 

• Adventitia. The outermost layer of the trachea is the adventitia. This layer consists of loose connective tissue. This layer also has blood vessels, nerves, and adipose tissue. It anchors the trachea to adjacent tissues and organs in the neck and thorax. 

What epithelium lines the bronchioles? 

Bronchioles are tiny branching tubes from the bronchi in your lungs. They are smaller than bronchi. This structure handles the delivery of air to the alveoli for gas exchange. The epithelium lining the bronchioles varies depending on the size of the bronchioles. 

Ciliated simple columnar epithelium lines the larger bronchioles. This epithelium type moves mucus and trapped particles upward. Once the trapped particles are in the bronchi and trachea, they expel these particles. 

Smaller bronchioles ( or terminal bronchioles) have ciliated simple cuboidal epithelium. The cilia continue to play a role in moving mucus and trapped particles. However, cilia in this part of the respiratory system are shorter. 

The respiratory bronchioles are the smallest branch. Simple cuboidal to simple squamous epithelia line this structure. The transition to simple epithelium facilitates gas exchange.

Where are the alveoli found? 

The alveoli are also known as air sacs. They are in alveolar ducts, sacs, and the terminal parts of the respiratory tract. Alveoli are also present in the lungs within the lung parenchyma. They are the primary sites for gas exchange between oxygen and carbon dioxide. 

The lung parenchyma is a functional tissue of the lung involved in gas exchange. The lungs have respiratory bronchioles, alveolar ducts, and alveolar sacs. All these structures have alveoli. 

There are also alveoli found at the terminal portions of the respiratory tract. This is the area where the bronchioles transition to alveolar ducts and sacs. Alveolar sacs are a group of alveoli clustered together. They open into alveolar ducts. 

Alveolar ducts are the passages that connect respiratory bronchioles to alveolar sacs. They also contain many alveoli along their walls. 

How many alveoli are in the lungs? 

The human lungs have about 300 to 500 million alveoli. This extensive network of alveoli provides a large surface area for gas exchange. An efficient functioning alveoli is crucial for acquiring oxygen and eliminating CO2 waste. 

The main function of the alveoli is to help the exchange of oxygen and carbon dioxide in the body. The large number of alveoli provides a bigger surface area for this exchange to occur. Alveoli in the lungs has an estimated surface area of 70 to 100 square meters. These numbers are about the size of a tennis court. The large surface area allows for rapid diffusion of gases. 

Also, the vast number of alveoli helps the lungs adapt to sudden respiratory changes. The millions of alveoli ensure the body has a reserve to compensate for damaged ones. 

When many alveoli get damaged, surface area decreases. This leads to a decrease in the efficiency of gas exchange. Very few alveoli counts could also result in low O2 levels in the blood, known as hypoxemia. 

The body may attempt to compensate for low oxygen by increasing respiration. However these mechanisms may not be enough to maintain normal gas exchange over the long term. 

The alveoli in the lungs are essential for maximizing gas exchange. It also ensures efficient respiratory function. Decreased alveolar number or function can lead to impaired gas exchange. Respiratory insufficiency could also happen. This insufficiency could contribute to the development of various respiratory diseases and symptoms. 

Conclusion 

The respiratory system is a complex network of organs and tissues. It works day in and day out to keep us alive. Its primary function is to bring in oxygen and expel carbon dioxide, a waste product. This gas exchange happens in the millions of tiny air sacs called alveoli within the lungs. 

A healthy respiratory system is the foundation of our well-being. Neglecting it through unhealthy choices can lead to a lifetime of struggle. 

References 

American Lung Association. (2020, February 27). How Does the Respiratory System Work? https://www.lung.org/lung-health-diseases/how-lungs-work 

Britannica. (n.d.). Nasal cavity. https://www.britannica.com/science/nasal-cavity 

Britannica. (n.d.). Olfactory epithelium. https://www.britannica.com/science/olfactory-epithelium Carla S. Silva Teixeira, Nuno M.F.S.A. Cerqueira, António C. Silva Ferreira, Unraveling the 

Olfactory Sense: From the Gene to Odor Perception, Chemical Senses, Volume 41, Issue 2, February 2016, Pages 105–121, https://doi.org/10.1093/chemse/bjv075 

Escada, Pedro & Lima, Carlos & Silva, José. (2009). The human olfactory mucosa. European archives of oto-rhino-laryngology : official journal of the European Federation of Oto-Rhino-Laryngological Societies (EUFOS) : affiliated with the German Society for Oto-Rhino-Laryngology – Head and Neck Surgery. 266. 1675-80. 10. 

Gartner, L. P., & Hiatt, J. L. (2020). Color Atlas and Text of Histology (7th ed.). Wolters Kluwer. Goncalves Ferreira, Miguel. (2020). Thermo-Mechanical Behaviour of Human Nasal Cartilage. 

Polymers. 12. 177. 10.3390/polym12010177. 

Guyton and Hall Textbook of Medical Physiology by John E. Hall. 

Junqueira, L. C., & Carneiro, J. (2005). Junqueira’s Basic Histology: Text and Atlas (11th ed.). 

McGraw-Hill. 

Kenhub. (n.d.). Anatomy of breathing: Process and muscles of respiration. https://www.physio-pedia.com/Muscles_of_Respiration 

Marieb, E. N., & Hoehn, K. (2016). Human anatomy & physiology (11th ed.). Pearson Education. National Institutes of Health. (n.d.). Anatomy of the Nose. MedlinePlus. 

https://www.ncbi.nlm.nih.gov/books/NBK532870

National Institutes of Health. (n.d.). Respiratory System. MedlinePlus. https://my.clevelandclinic.org/health/body/21205-respiratory-system 

Professional, C. C. M. (n.d.). Respiratory system. Cleveland Clinic. https://my.clevelandclinic.org/health/body/21205-respiratory-system 

Ross, M. H., & Pawlina, W. (2015). Histology: A Text and Atlas (7th ed.). Lippincott Williams & Wilkins. 

Wheater’s Functional Histology: A Text and Colour Atlas by Barbara Young, James S. Lowe, Alan Stevens, and John W. Heath 

 

Written by Christine C. Gubatayao

Reviewed by Dr. Reuben J C. los Baños, Ph.D.

Why is the skin important to the human body? One of the most vital parts of your body is your skin. The biggest organ in the human body is the skin. It acts as the main line of defense against the outside world. Skin, hair, and more structures allow all living things to keep and protect their features. The components of the skin are water, proteins, lipids, and minerals. 

UV protection, antioxidant, and antibacterial properties of skin are among its protective qualities. Imagine without a skin; you are not protected from microorganisms. You are not able to sense pain. It is thus possible to suffer harm without being aware of it. Your organs, bones, and muscles would protrude from the skin in all directions. 

How does skin protect the body? 

Skin connects everything, including: 

Keeps you protected from infections: 

The skin serves as the body’s primary physical barrier against the external environment. It protects against microorganisms, dehydration, UV light, and mechanical injury. This is important because the skin covers the majority of the human body. The skin is a packed network of cells. Each stratum adds to its durability. The body’s protective layers are the dermis, hypodermis, and epidermis. 

Controls body temperature: 

Vasoconstriction and vasodilation are part of the skin’s vast vascularization. It enables it to store and release heat. Blood vessels widen to enhance blood flow. Thus, optimize heat dissipation when temperatures rise. 

Immune protection: 

The skin serves as the body’s initial line of defense by acting as a physical barrier. This is to keep infections from entering the body. Keratin filaments provide support for the junction proteins that link cells together. The native immune cells are what provide immunity. 

Vitamin creation: 

Vitamin D production begins with metabolic processes initiated by the skin. The principal sources of vitamin D are sun exposure and oral intake. It is necessary for healthy bone metabolism and the absorption of calcium. 

Stimulus detection: 

The skin’s sensory nerve endings detect pain, temperature, touch, and vibration. The four types of mechanoreceptors that mediate benign touch are: 

• Meissner corpuscle 

• Pacinian corpuscle 

• Ruffini endings 

• Merkel cells 

The rates of adaptation and conduction differ through receptor and nerve fiber types. As a result, several signals arise. The body works together to understand and react to its environment. 

Exocrine function: 

This happens when ammonia, urea, and water get released. The skin secretes chemicals such as sweat, pheromones, and sebum. Thus, secreting biologic agents like cytokines serves a vital role in immunologic processes. 

Motility: 

The skin permits the body to move well. 

What is the microscopic structure of the skin? 

From an embryological perspective, the surface ectoderm gives rise to the epidermis. Melanocytes, which are pigment-producing cells derived from the neural crest, have penetrated it. The tactile receptor that senses pressure is the Merkel cell. Its pressure changes near the base of the epidermis. The Langerhans cells are antigen-processing. More cell types present in the epidermis are keratinocytes. 

Dermis originates from the mesoderm and contains connective tissue macromolecular components and cells. This includes elastic fibers, collagen, nerves, blood vessels, adipocytes, and fibroblasts. 

There are three main layers to the skin. Epidermis, dermis, and subcutaneous. 

• the epidermis, the skin’s outermost layer. It alters skin tone and acts as a barrier against water. 
• The dermis lies underneath the tissue. It contains sweat glands, blood vessels, lymphatic vessels, hair follicles, and connective tissue. 
• Fat and connective tissue make up the hypodermis, or deeper subcutaneous layer. 

When it comes to thick skin, such as the palms and soles, the epidermis is further separated into five layers. 

• Stratum basale 

• stratum spinosum 

• stratum granulosum 

• stratum lucidum 

• stratum corneum 

The dermis consists of two layers: the reticular dermis at the bottom and the papillary dermis at the top. 

What type of tissue is found in the integumentary system? 

The skin consists of several tissue types. Stratified squamous epithelia make up the epidermis, which qualifies as epithelial tissue. The several types of connective tissues that formed the dermis include: 

• Areolar Connective Tissue 

• Dense Irregular Connective Tissue 

• Histiocytes (Tissue Macrophage) 

• Adipose Tissue 

• Glands 

What are the two major components of the integumentary system? 

The Integumentary System’s major components are the skin and accessory structures. 

1. The skin consists of two layers: the surface epidermis and the deeper dermis. 

2. The skin’s accessory structures include the sebaceous glands, sweat glands, hair, and nails. These structures arise in the epidermis and all the way through the dermis to the hypodermis. 

The skin’s accessory structures consist of: 

• The dermis lies underneath the tissue. It contains sweat glands, blood vessels, lymphatic vessels, hair follicles, and connective tissue. 

• Fat and connective tissue make up the hypodermis, or deeper subcutaneous layer. 

When it comes to thick skin, such as the palms and soles, the epidermis is further separated into five layers.

• Stratum basale 

• stratum spinosum 

• stratum granulosum 

• stratum lucidum 

• stratum corneum 

The dermis consists of two layers: the reticular dermis at the bottom and the papillary dermis at the top.

What type of tissue is found in the integumentary system? 

The skin consists of several tissue types. Stratified squamous epithelia make up the epidermis, which qualifies as epithelial tissue. The several types of connective tissues that formed the dermis include: 

• Areolar Connective Tissue 

• Dense Irregular Connective Tissue 

• Histiocytes (Tissue Macrophage) 

• Adipose Tissue 

• Glands 

What are the two major components of the integumentary system?

The Integumentary System’s major components are the skin and accessory structures. 

1. The skin consists of two layers: the surface epidermis and the deeper dermis. 

2. The skin’s accessory structures include the sebaceous glands, sweat glands, hair, and nails. These structures arise in the epidermis and all the way through the dermis to the hypodermis. 

The skin’s accessory structures consist of: 

• Hypodermis 

Between the dermis and the underlying organs is the hypodermis. It is also known as subcutaneous tissue and consists of adipose and loose areolar tissue. This layer links the skin to underlying components. For example, muscle stores fat, which serves as an extra cushion and insulation. 

• Hair 

Although it originates in the epidermis, hair roots in the dermis. Its anatomy splits between the hair follicle located within the epidermis. The hair shaft that is visible from the outside. The hair falls into two categories: 

1. Androgen-independent vellus hairs that cover the remaining areas 

2. Hormone-dependent, thicker terminal hairs in areas like the pubic areas, scalp, chest, etc. 

The hair follicle has a structure that contains the hair bulb that divides to extend the hair shaft. The phases of hair growth that’re regulated by hormones and growth, known as: 

1. anagen (growth phase) 

2. catagen (nonproliferative phase), 

3. telogen (resting phase) 

The majority of the body has been covered in hair. Except for the region of lips, palms, soles, and external genitalia. Hair improves sensory perception, protects the skin , and helps control body temperature. Dermal muscles (arrector pili) stick to follicles and help the shaft hold its position. Also, it retains air near the epidermis to regulate temperature. 

• Nails 

At the dorsal points of the fingers and toes, nails consist of layers of keratin. The growth of nails starts at the nail matrix, where new cells form. Older cells moved out in a distal direction. The part of the nail that is visible is the nail plate that covers the nail bed and connects to the finger. Also to improve sensitivity and movement precision, nails shield the fingers and toes. 

• Associated Glands: 

The four different types of exocrine glands found in human skin are: 

1. Sudoriferous 

2. sebaceous 

3. ceruminous 

4. mammary glands 

The sweat glands referred to eccrine and apocrine glands subtypes of sudoriferous glands. Apocrine glands located in the axilla and pubic region. It secrete milky, protein-rich sweat. 

These glands are in charge of odor as bacteria break down the organic materials they release. Eccrine glands circulate over the body. Hence, produces serous fluid to control body temperature. 

Sebaceous glands secrete sebum, a mixture of lipids that forms a thin layer on the skin. It is part of the pilosebaceous unit, which includes the hair, hair follicle and arrector pili. This layer acts as an antibacterial, gives a layer of protection, and stops fluid loss.

How do the parts of the integumentary system work together? 

Your body resembles an intricate mechanism. To keep in balance and work as it should, your organs, body parts, and systems all cooperate. Other systems rely on your integumentary system to keep functioning. 

Your immune system is the first line of defense against bacteria and infections. For instance, it benefits your immune system. White blood cells are also sent to wounds to start the healing process. 

Vitamin D, which functions as a hormone. It influences calcium absorption that is essential for the health of your bone. Thus, it absorbs with the aid of your integumentary system. Since they filter out dust and other pollutants from the air before you inhale them. 

What are the specialized cells in the integumentary system? 

Many specialized cells and structures located in the skin, such as: 

• Basket Cells 

Capable of sensing pressure, basket cells encircle the base of hair follicles. When evaluating the general health and condition of the nerves, they’re examined. 

• Vascular Structures 

Vascular structures transport waste materials and oxygen-rich blood to the skin’s cellular layers. 

• Hair Erector Muscle (Arrector Pili Muscle) 

Each hair follicle and the skin connect to the arrector pili muscle, a small muscle. It causes a “goosebump” to grow on the skin and the hair to stand erect as it contracts. 

• Hair Follicle 

The hair follicle is a tube-shaped sheath structure. It envelops and nourishes the part of hair beneath the skin. Both the dermis and the epidermis contain it. 

• Hair Shaft: 

The hair shaft is the part of hair that lies above the skin. The hair root penetrates the deeper layers of the skin. A sheath of skin and connective tissue surrounds each hair follicle. connections to the sebaceous gland. 

• Langerhans Cells: 

These cells identify antigens that penetrate damaged skin. It binds them to notify the immune system of their existence. The LC of the epidermis is the most researched example. The Birbeck granule is distinctive. A shape like a rod or tennis racket. Is what makes them identifiable via electron microscopy. 

• Melanocytes 

The pigment known as melanin gets generated by skin cells called melanocytes. It dwells in the epidermis’ basal layer and harms or develops lesions as a result of UVA exposure. Melanin functions as a protective barrier, stopping UV radiation from damaging DNA. As a result, skin cancer may result. 

• Merkel Cells 

The Merkel cells are tactile cells with neuroectodermal origins. It lies in the basal layer of the epidermis. 

• Pacinian Corpuscle 

It reacts to pressure and vibration known as a nerve receptor. The pacinian corpuscle lies in the subcutaneous fatty tissue. 

• Sebaceous Gland 

The sebaceous glands are tiny, sack-shaped glands. It coats and shields the hair shaft from breaking down by secreting an oily substance. The dermis contains these glands. 

• Sensory Nerves 

 Sensory nerves innervate the epidermis. Heat, discomfort, and other unpleasant sensations get sensed and transmitted by these nerves. Sensations like tingling, burning, discomfort, numbness, or pins and needles. It can become experienced when they are not working. Total number, contiguity, diameter, branching, swelling, and general health of sensory nerves. It will undergo assessment when analyzing a skin sample. 

• Stratum Corneum 

Dead skin cells make up the stratum corneum, the outermost layer of the epidermis. The skin’s lower layers act as a strong barrier between the environment. It shields the living cells underneath it. Because the stratum corneum can thin more than usual. Thus, under certain circumstances, it is helpful for diagnosis. 

• Sweat Gland (Sudoriferous Gland) 

These epidermis-based glands discharged moisture, or sweat, onto the skin’s surface. It is being released through tiny channels. Sweat evaporates, lowering the skin’s warmth. 

How does the integumentary system maintain homeostasis? 

The skin, hair, nails, and glands all work together to keep the body safe and stable. The following body systems are in communication with the integumentary system: 

• The immune system 

It contains immune cells. It serves as a physical barrier against pathogenic microorganisms. The immune system keeps track of every germ it has ever beaten. So that it can identify and destroy the microbe if it enters the body again. 

• Digestive system 

Vitamin D gets delivered to the digestive system by the skin. The vitamin aids in calcium absorption. Thus, it needs to occur for bone maintenance and muscular contractions. 

• Cardiovascular system 

To keep or release heat, the blood vessels in the skin can dilate or contract. The rest of the body receives oxygenated blood from the heart via arteries. To restart circulation, the veins return blood that is low in oxygen to the heart. 

• Nervous system 

Information from sensations travel from the skin to the brain via nerve receptors. These include feeling pain, heat, cold, and other sensations. 

• Respiratory system 

Toxic particles get stopped from entering the lungs by microscopic hairs. It lines the nose passages. The voice box, windpipe, nose, mouth, throat, and lungs are all part of the respiratory system. The mouth or nose are the entry points for air into the respiratory system. The air gets heated and made more humid if it enters the nostrils, also known as the nares. 

• Urinary system 

The kidneys work with the skin’s discharged waste products. Thus, to maintain the body’s pH and electrolyte equilibrium 

References: 

Mph, Z. S. (2023, November 27). What to know about the integumentary system. https://www.medicalnewstoday.com/articles/integumentary-system#linked-conditi ons 

Anatomy of the Skin | SEER Training. (n.d.). https://training.seer.cancer.gov/melanoma/anatomy/ 

Professional, C. C. M. (n.d.). Integumentary System. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22827-integumentary-system 

Kim, J. Y., & Dao, H. (2023, May 1). Physiology, Integument. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK554386/ Lopez-Ojeda, W., Pandey, A., Alhajj, M., & Oakley, A. M. (2022, October 17). 

Anatomy, Skin (Integument). StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK441980/#:~:text=The%20skin%20is%2 0primarily% 

Written by Francine Marianne A. Caseres

Reviewed by Reuben J C. Los Baños, Ph.D.

Made up of complex networks of cells, your digestive system is a vital organ that you can’t live without! You’re able to absorb nutrients and excrete waste through this system. And with it, you’re able to complete your daily tasks and get through the day. 

This complex system has many histological aspects that are essential for its actions. Among these are your different cells, histological layers, and others. Let’s discuss these one by one! 

The digestive system has your alimentary canal. It also has your accessory digestive organs. These include the salivary glands, teeth, pancreas, liver, and gallbladder. These are all necessary so that they may help in the digestion of food. 

Intestinal Cells 

Among the most significant cells present are the epithelial cells in your intestines. The columnar epithelium helps absorb the nutrients needed in our body. As well as enterocytes, goblet cells, Paneth cells, and enteroendocrine cells. 

Enterocytes 

Involved in the chemical digestion of food, these cells line the intestines. They also form the brush border, which is a barrier for the absorption of food. This includes their ions, water, and nutrients. 

Goblet Cells 

These cells secrete mucus, which protects and lubricates the intestines. 

Paneth Cells 

The Paneth cells are in charge of the small intestine’s germ-killing output. They also help renew the intestine’s lining. 

Enteroendocrine Cells 

They aid in digestion by secreting many peptide hormones. They also regulate intestinal motility and food intake. 

Stomach Cells 

Many types of cells are also found on the stomach. Their main job is to break down materials using acid and enzymes. The stomach has four cell types. They are the chief, mucous neck, enteroendocrine, and parietal cells. 

Chief Cells 

These cells secrete pepsinogen, which breaks down proteins when activated.  

Mucous Neck Cells 

These types of cells located in the gastric glands of the stomach secrete acidic mucus. 

Enteroendocrine Cells 

These cells in the stomach differ from those in the intestine. In the stomach, these cells can secrete hormones, particularly gastrin. Gastrin’s main function is to make the stomach secrete hydrochloric acid. This acid kills bacteria and helps digest food. 

Parietal Cells 

These cells produce hydrochloric acid and the intrinsic factor. This factor enables the absorption of vitamin B12. 

What are the histological features of the digestive system?  

The digestive system can take in food. It absorbs nutrients and removes indigestible materials.  

Aside from the different cells in the digestive system, this system also has two types of organs. Some belong in the GI tract. Others belong in the accessory organs. All these play a huge part in your body’s functions.  

The GI tract has many parts. These include the mouth, pharynx, esophagus, stomach, small intestine, large intestine, and anus.  

• Mouth – The mouth aids in the mechanical processing of food. The cheeks, tongue, uvula, hard palate, and soft palate form this. They’ve mixed food with saliva. 

• Pharynx – Its pharyngeal muscles propel materials into the esophagus. It is composed of skeletal muscles and is covered with mucus. 

• Esophagus – The esophagus transports materials to the stomach. Including the transportation of bolus from the mouth to the stomach. This 25-centimeter tube starts from the interior end of the laryngopharynx.  

It then ends at the superior part of the stomach. 

• Stomach – This organ aids in the chemical breakdown of materials. It has four main regions namely, the cardia (surrounds superior opening), fundus (left to the cardia), body (large central portion), and pylorus (connects the stomach to the duodenum).  

• Small Intestine – This aids in the enzymatic digestion and absorption of water, vitamins, ions, and organic substrates. The small intestine also has three major parts namely the duodenum, jejunum, and ileum. These will be discussed later on.  

• Large Intestine – The colon, the cecum, the anal canal and the rectum are the four major regions that compose the large intestine. It dehydrates and compacts undigested food materials, in preparation for elimination. 

• Anus – This is the last part of the GI tract and lubricates the passage to help the feces pass through smoothly. 

The accessory digestive organs also aid in digestion. These are the salivary glands, teeth, pancreas, liver, and the gallbladder. 

• Salivary glands – These glands secrete fluid that help breakdown carbohydrates. They release saliva into the oral cavity for this purpose. The three types of glands are the parotid, submandibular, and sublingual glands. 

• Teeth – Teeth aids in cutting, tearing, and pulverizing solid food. 

• Pancreas – This organ secretes digestive enzymes to digest protein. They also secrete a certain hormone, insulin, to control blood sugar levels of your body. 

• Liver – This organ secretes bile which is important for lipid digestion. They also store nutrients. Located just below the diaphragm, this is the 2nd largest organ in the human body. 

• Gallbladder – The gallbladder acts as the storage for bile. It is located beneath the liver and is a small, pear-shaped organ. 

Most of the digestive system is also composed of four histological layers. These four distinct layers are all vital to its function. These are the mucosa, submucosa, muscularis externa, and the serosa. 

Mucosa 

This is the digestive system’s innermost layer. This has loose connective tissue and simple columnar epithelium with goblet cells. These are all divided into different layers of the mucosa. 

The three layers are the epithelium, the lamina propria, and the muscularis mucosae. The lamina propria is a type of loose connective tissue. This muscularis mucosae takes part in the formation of folds. 

Submucosa 

The second layer supports the mucosa. It’s rich in blood vessels, nerves, and lymphatic vessels. This is also made up of dense irregular connective tissue. 

Muscularis externa 

Two layers of smooth muscle compose the muscularis. This layer is responsible for the peristalsis movement of the digestive system which is controlled by the nerve plexus. 

Serosa 

A simple squamous epithelium makes up the outermost layer of the digestive system. It also can also have a small amount of underlying loose connective tissue.  

What is the stomach cell that produces gastric acid? 

Hydrochloric acid makes up gastric acid, which aids in digesting food. The cells that produce it are the parietal cells. The parietal cells are located in the proximal two-thirds, or body of the stomach. 

What are the histological layers of the stomach?  

The stomach is part of the digestive system. It’s in the gastrointestinal (GI) tract, which compromise most of the system. It has four distinct layers, just like the layers of the digestive system. These are the mucosa, submucosa, muscularis, and the serosa. 

Mucosa 

This is the stomach’s innermost layer. It releases digestive juices through its glands.  

Submucosa 

The second layer supports the mucosa. It’s rich in blood vessels, and contains the submucosal nervous plexus. 

Muscularis 

This helps mix the food with digestive juices in it. 

Serosa 

This is the outermost layer of the stomach. This layer also confines the stomach as it wraps around it. 

What is the stomach cell that produces gastric acid? 

Hydrochloric acid makes up gastric acid, which aids in digesting food. The cells that produce it are the parietal cells. The parietal cells are located in the proximal two-thirds, or body of the stomach. 

What is the histology of the duodenum? 

The duodenum is actually found in the first part of the small intestine. In this region, the body mixes bile and digestive juices with the food to aid in further digestion. Vitamins, minerals, and other nutrients are also absorbed here. 

The duodenum is like other GI organs. It has the mucosa, submucosa, and muscularis layers. The duodenum has a unique feature. It has microvilli, villi, and Brunner’s glands. 

Microvilli  

Actin filaments support the microvilli. They are protrusions on the surface of different cell types. 

Villi 

Villi are small projections. They enable maximum nutrient absorption by increasing surface area. 

Brunner’s Glands 

Cuboidal and columnar cells make up these glands and secrete neutral mucin. These glands are also similar to the glands in the distal gastric mucosa and periampullary region. But, they have a nodular appearance on the mucosal surface. 

What is the histology of the jejunum? 

You call the middle region of your small intestine the jejunum. Proteins, fats, cholesterol, and water absorb here. Like your whole small intestine, the jejunum has its own mucosa, submucosa, muscularis, and serosa layers.  

The jejunum has key features. They are the Lieberkuhn crypts and villi. The intestinal lumen contains them.  

Lieberkuhn crypts 

These crypts are tubular glands. They secrete intestinal juice and are formed from the mucosa at the bases of the villi. You can also find Paneth cells and stem cells in these crypts. 

What is the role of the large intestine in the digestive system?  

The large intestine, also known as the colon, plays an essential role in your body. The rectum and anus are also in your large intestine. They’re important in fulfilling the activities of your daily lives.  

But first, what exactly is the large intestine? 

It’s in the last part of your GI tract. Mainly, it absorbs water and eliminates solid waste. Dehydration and the compaction of indigestible materials also happen here. They’re prepared for elimination. 

Your large intestine is 1.5 meters long. It extends from the cecum to the anus. The large intestine has four main parts: the cecum, colon, rectum, and anal canal. 

Cecum  

The cecum is a small pouch-like organ that is present next to the ileocecal sphincter. The cecum’s main job is to get food from the small intestine. It then moves the food to the large intestine. 

Colon 

This is where the final absorption of water and electrolytes takes place. The colon secretes mucus to bind and lubricate food waste. This helps it pass through the intestine smoothly. 

Rectum  

This composes the last 20 centimeters of the GI tract. In this region, the food waste, now in the form of feces, triggers the urge to defecate. Defecation, in turn, is so important for our body so we may be able to get rid of our own toxins. 

Anal Canal 

As feces leaves your body, it travels through your anus, marking the end of the digestive cycle. 

What are the major histological features of the large intestine?

The large intestine is made of columnar epithelial cells. They are able to absorb materials well. It also has many goblet cells, basal stem cells, and endocrine cells. Yet, there is no striated border nor Paneth cells.  

Like the small intestine, the large intestine also has its own histological layers. These include the mucosa, its lamina propria, submucosa, and muscularis externa. 

Like that of the small intestine are the lamina propria and submucosa. 

The muscularis externa is different from the small intestine, in contrast. It is arranged in three long bands called taenia coli. 

Lastly, the mucosa has no villi, unlike other structures of the digestive system. But instead of villi, the large intestine has crypts. 

The Digestive System as a Whole 

Together with the GI tract and accessory organs, they make up your digestive system. And your body would function poorly without it.  You may not be able to enjoy tasting and eating food, nor excrete the toxins of your body. 

Constipation, the lack of bowel movement, is also common. It affects one-third of adults over 60. In fact, without treatment, severe constipation can lead to bowel problems. In severe cases, it could lead to hospitalization, surgery, and even death. 

Thus, the role of our digestive system is essential in our lives. No one can live without it, and it’s up to you to take good care of this system. 

To eat a good diet and exercise regularly is one of the key things that can affect your body healthily. The histology of the digestive system is fascinating. All the cells and tissues involved would help you thrive. They enable your organs to work normally. 

References 

Britannica. (2018). Villus | anatomy. In Encyclopædia Britannica. https://www.britannica.com/science/villus 

Brunner’s Glands – an overview | ScienceDirect Topics. (n.d.). http://Www.sciencedirect.com. https://www.sciencedirect.com/topics/medicine-and-dentistry/brunners-glands 

Cleveland Clinic. (2021, December 8). Colon (Large Intestine): Function, Anatomy & Definition. Cleveland Clinic; Cleveland Clinic. https://my.clevelandclinic.org/health/body/22134-colon-large-intestine 

Constipation: Risks and more. (2023, May 25). http://Www.medicalnewstoday.com. https://www.medicalnewstoday.com/articles/death-by-constipation 

Crypts of lieberkuhn are formed from the. (n.d.). Byjus.com. Retrieved May 26, 2024, from https://byjus.com/question-answer/crypts-of-lieberkuhn-are-formed-from-thethe-mucosa-of-the-small-intestine-the-submucosa-of/# 

‌Duodenum. (n.d.). Kenhub. https://www.kenhub.com/en/library/anatomy/the-duodenum# 

‌Enterocyte | biology | Britannica. (2019). In Encyclopædia Britannica. https://www.britannica.com/science/enterocyte 

Histology of the digestive system. (n.d.). Kenhub. https://www.kenhub.com/en/library/anatomy/digestive-system-histology 

Jejunum (small intestine) | Gastrointestinal Tract. (n.d.). Histologyguide.com. https://histologyguide.com/slideview/MHS-219-jejunum/14-slide-1.html 

Karunaharamoorthy, A. (2021, October 28). Jejunum. Kenhub. https://www.kenhub.com/en/library/anatomy/the-jejunum 

MedlinePlus. (2017). Duodenum: MedlinePlus Medical Encyclopedia. Medlineplus.gov. https://medlineplus.gov/ency/article/002347.htm 

‌Paxton, S., Peckham, M., & Knibbs, A. (2003). The Leeds Histology Guide. Www.histology.leeds.ac.uk. https://www.histology.leeds.ac.uk/digestive/large_intestine.php#:~:text=The%20thick%20mucosa%20has%20deep 

Physiopedia. (n.d.). Goblet Cells. Physiopedia. https://www.physio-pedia.com/Goblet_Cells 

‌The Editors of Encyclopaedia Britannica. (2023, May 18). Microvillus | Description, Anatomy, & Function | Britannica. http://Www.britannica.com. https://www.britannica.com/science/microvillus 

The Stomach | Anatomy and Physiology II. (n.d.). Courses.lumenlearning.com. https://courses.lumenlearning.com/suny-ap2/chapter/the-stomach/#:~:text=These%20include%20parietal%20cells%2C%20chief 

University of rochester medical center. (2019). Anatomy of the Stomach – Health Encyclopedia – University of Rochester Medical Center. Rochester.edu. https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=34&contentid=17785-1 

‌Vakil, N. (2021, June). Overview of Acid Secretion – Gastrointestinal Disorders. MSD Manual Professional Edition. https://www.msdmanuals.com/professional/gastrointestinal-disorders/gastritis-and-peptic-ulcer-disease/overview-of-acid-secretion 

‌ 

Written by Cliantha Marielle S. Asonan

Reviewed by Dr. Reuben J C. los Baños, Ph.D.

What is the structure and function of the organs of the urinary system? The urinary system is an amazing part of the body. It includes bean-shaped kidneys, tubes called ureters and urethra, and the shapeshifting bladder. Each of these organs works together to filter blood and produce urine.

Have you ever wondered how the water you drink leaves your body? How about the way the body regulates blood pressure? And has it ever come across your mind what stimulates the creation of blood in the body?

What if I told you that all the functions mentioned are the work of the urinary system? That’s right – the urinary system does more than its name suggests. It does more than produce urine, and this article will tell you more about it.

As mentioned, the urinary system includes four different organs. These are the kidneys, the ureters, the bladder, and the urethra. They work in constant unison to perform many roles in the body.

The first organ of the bunch is the kidney, and have two of these bean-shaped structures in your body. As the most complex in structure, the kidneys are the main actors in filtering blood and making urine. Knowing its structures will help you understand the production of urine later on.

Here are some functions of the kidneys:

1. The kidney regulates the salt, potassium, and acid content of the body (National Kidney Foundation, n.d.).
2. They also release the hormone called renin. Renin is an important hormone in regulating blood pressure (Mescher, 2021).
3. It controls the production of red blood cells. It does this by secreting erythropoietin, another hormone (National Kidney Foundation, n.d.).

• It produces the active form of Vitamin D called calcitriol. This helps promote the health of the bones in the body (National Kidney Foundation, n.d.).
• It removes drugs from the body along with other bioactive substances (Mescher, 2021).
• It balances the amount of fluids in the body (National Kidney Foundation, n.d.).

Moving along, the next organ in the urinary system is the ureter. The ureter is tubular in structure. It channels urine from the kidney to the bladder (Mescher, 2021).

Each kidney has a ureter attached to it. That means that you have two ureters in your body. Each ureter connects to the bladder, which is the next organ in the system.

The urinary bladder is where the urine from the kidney goes and awaits excretion. It does something amazing – it changes from triangular to oval as it collects urine. A latter section of this article will reveal how the bladder is able to do this.

Finally, at the bottom part of the bladder is the urethra. It is a single tube that is longer in males than in females. The urethra is where the urine flows from the bladder to the outside of the body.

What organ of the urinary system produces urine?

Our blood carries waste products that the body needs to remove in the form of urine.

Inside the urinary system, an organ acts like a filtering factory. The primary organ of the urinary system that produces urine is the kidney.

The kidney allows blood to enter and exit while filtering its contents. It does this through a series of tubes of varying sizes. The blood comes from the renal artery and exits through the renal vein.

The following is the process of making urine within the kidney according to Mescher (2021):

1. Blood enters the kidney through the renal artery

• The renal artery branches into smaller arteries – segmental, interlobar, arcuate, and interlobular. Blood travels through these vessels until they reach the nephron.

• In the nephron, blood pressure forces fluids and waste into the glomerulus.

• The remaining blood exits the glomerulus. The filtrate flows through tubules in the nephron.
• The tubules reabsorb water and needed substances back into the bloodstream.

• Cleansed blood and reabsorbed materials flow through a system of veins. They pass through the interlobular veins to the arcuate, and interlobar, renal veins.

• Waste products left behind in the tubules become urine. It passes through the collecting ducts through the renal pyramids. Urine then passes through the calyces and to the ureter.

What types of tissue can you find in the urinary system?

Despite having only four organs, the urinary system contains all four major tissues. The presence of these ensures the proper functionality of the system as a whole. The urinary system contains different types of muscular, epithelial, and connective tissues.

Muscle Tissue

Smooth muscles compose the muscularis layers of the ureters, bladder, and urethra. At the middle part of the urethra, you can find a sphincter composed of striated muscle. This is the part that you can control when you want to either urinate or hold your pee.

Connective Tissue

Loose areolar connective tissue surrounds the blood vessels and nerves. Dense connective tissue composes the capsule and the lamina propria of the bladder.

Adipose tissue is also present in the perirenal fat that cushions the kidney (Pirie, 2023).

Nervous Tissue

Many nerves provide signals from the nervous system to the urinary system. Some are the thoracolumbar splanchnic nerve, the vagus nerve, and the intermesenteric plexus. In the ureter, one can also find many nerve plexuses that innervate it.

The urinary system contains a wide variety of epithelial tissue. You can read about this in the following section.

What type of epithelium lines the urinary system?

The urinary system contains various epithelial tissues. It has simple cuboidal, columnar, transitional, and simple squamous epithelia.

• It has simple cuboidal epithelia, which are present in the kidney tubules. You can also find it in the collecting ducts.
• Principal cells of the collecting system can range from cuboidal to columnar epithelia.
• The urinary system also has transitional epithelia present in the bladder and ureters.
• Simple squamous epithelia line the thin descending limb of the loop of Henle.

• Pseudostratified epithelia line the membranous urethra.

• Among males, stratified columnar epithelia line the spongy urethra.

• Nonkeratinized squamous epithelium line the end of the urethra among females.

The variety of these epithelia found in different parts of the urinary system is crucial. The structure of these epithelia reflects their function in the system.

What is the histology of the kidney?

Given its many parts, you could expect that there are many types of tissues present in the kidney. These tissues serve different roles that all contribute to the function of kidneys. The kidney contains connective, epithelial, muscular, and nervous tissues.

From the outside view of the kidney, you can find two structures. The first is the capsule surrounding the kidney made of fibrous connective tissue. The other is the hilum, where the nerves, blood and lymph vessels, and ureters enter (Mescher, 2021).

Inside the kidney, you can find even more complex structures that all take part in making urine. The one end of the ureter that enters the kidney extends as the renal pelvis. The pelvis divides into major calyces that branch into minor calyces (Mescher, 2021).

The kidney also has the renal cortex and the renal medulla. The renal cortex is the outer part of the inner structure and has many corpuscles and tubules. The medulla contains renal pyramids whose bases meet at the cortex (Mescher, 2021).

The end of each pyramid opposite the cortex called the renal papilla connects to a minor calyx. Between the renal pyramids are extensions of the cortex – renal columns (Mescher, 2021).

The functional units of the kidney are the nephrons. Each nephron has a renal corpuscle and a system of tubes composed of three parts. These are the proximal and distal convoluted tubules and the loop of Henle (Mescher, 2021).

Crumbie (2023) says both the sympathetic and parasympathetic nervous systems innervate the kidneys. The thoracolumbar splanchnic nerve provides vasomotor supply. The kidney also has fibers of the vagus nerve and the intermesenteric plexus.

What is the histology of the ureter and bladder?

The ureter and the bladder have similar histologic structures. The ureter consists of three layers: the mucosa, muscularis, and adventitia. Meanwhile, the bladder has four layers: the mucosa, submucosa, muscularis, and adventitia.

The mucosa of both the ureter and bladder consists of the urothelium. The urothelium is a transitional epithelium, and these have a special ability. They can become thick or squamous cells depending on the conditions of these organs. According to Mescher (2021), the urothelium has three layers:

1. Basal cells forming a single layer on top of the basement membrane
2. A middle region of at least one layer of cuboidal or low columnar cells

• An apical layer of umbrella cells, which are bulbous or elliptical. They specialize in protecting underlying cells from the hypertonicity of urine. They are most developed in the urinary bladder.

An adventitial layer covers both the ureter and the bladder. An exception to this would be the upper part of the bladder. Instead of adventitia, a covering of serous peritoneum lines this area (Mescher, 2021).

In the ureter, you can find a thick muscularis. These function to move the urine from the kidney to the bladder through peristalsis. The muscularis also makes folds in the mucosa when the lumen of the ureter is empty.

Meanwhile, the urothelium of the urinary bladder varies in thickness (Ferng, 2023). The thickness depends on the amount of urine stored in the bladder. Its thickness when the bladder is full is half the thickness when the bladder is empty.

A lamina propria and an underlying submucosa surround the urothelium. The submucosa consists of dense irregular connective tissue. Within these layers, you can find many blood vessels.

Underneath the submucosa is a dense layer of muscle followed by an adventitia. The muscularis consists of the detrusor muscle, an interwoven layer of smooth muscles. They contract to empty urine from the bladder (Mescher, 2021).

What is the histology of the loop of Henle?

The loop of Henle consists of a thin descending limb and a thick ascending limb. Together, they form a U-shaped structure. The loop of Henle contains simple squamous as well as simple cuboidal epithelium.

The histology of the thin limb consists of simple squamous epithelia. It also has few mitochondria and organelles (Mescher, 2021). It functions in the passive reabsorption of sodium and chloride ions.

Meanwhile, the thick ascending limb consists of simple cuboidal epithelium. It contains no microvilli and has many mitochondria (Mescher, 2021). Its function is the active reabsorption of various electrolytes.

The thin limb sits in the medulla while the thick limb sits in the medulla and the medullary rays (Mescher, 2021).

What is the histology of the glomerulus?

The glomerulus is a bed of capillaries. It connects to an afferent arteriole at one end and an efferent arteriole at the other. These capillaries consist of fenestrated endothelial cells.

The glomerulus has a covering called the glomerular capsule or Bowman’s capsule. The outside of this is a layer of squamous epithelium supported by a basal lamina (Mescher, 2021). It is continuous with the proximal tubule, where the epithelia become simple cuboidal.

The capillaries of the glomerulus work together with podocytes. They work together with these stellate epithelia to proceed with renal filtration. Primary processes from the podocytes curve around these capillaries.

The primary processes also have many pedicels covering the capillary surfaces. These pedicels are in contact with the basal lamina. Between these pedicels are slit diaphragms – tight junctions containing nephrins (Mescher, 2021).

A thick glomerular basement membrane lies between the capillaries and the podocytes. This membrane is important in separating blood from the capsular space. This restricts large proteins and some organic ions (Mescher, 2021).

You can also find mesangial cells, which support the capillaries of the glomerulus. They also adjust the contractions based on the blood pressure. Mesangial cells also work in immune defense and glomerular repair (Mescher, 2021).

Conclusion

The urinary system plays a vital role in maintaining our health. It filters waste and extra water from the blood, balancing fluids and electrolytes. By removing toxins, it regulates blood pressure and prevents buildup.

It is thus important to take care of your urinary system. Drink plenty of water and eat the right food. Keep the urinary system happy as it works non-stop to keep you healthy.

References:

Crumbie, L. (2023). Neurovascular supply of the kidney. Kenhub. https://www.kenhub.com/en/library/anatomy/neurovascular-supply-of-the-kidney

Ferng, A. (2023). Urinary bladder. Kenhub. https://www.kenhub.com/en/library/anatomy/urinary-bladder

Mescher, A. (2021). Junqueira’s basic histology: Text & atlas. McGraw-Hill Education.

National Kidney Foundation. (n.d.). How your kidneys work. National Kidney Foundation. https://www.kidney.org/kidneydisease/howkidneyswrk

Pirie, E. (2023). Kidney histology. Kenhub. https://www.kenhub.com/en/library/anatomy/kidney-histology

Written by Almarie Joy B. Florida

Reviewed by Dr. Reuben J C. los Baños, Ph.D.

Nervous tissue conducts and transmits electrical signals in your body. The body calls these signals nerve impulses or an “action potential.” It enables rapid communication between your body parts. It supports sensory perception, motor coordination, and thinking. Also, it supports and regulates the activities of other cells.

Two Major Divisions of Nervous System

• Central Nervous System (CNS) – composed of cerebrum, cerebellum, spinal cord

• Peripheral Nervous System (PNS). – composed of cranial nerves, spinal nerves, ganglia

Your neurons, also called nerve cells, carry out the nervous system’s functions. They do this by responding to stimuli. They transmit chemical and electrical signals, which cause an action potential. The anatomical structure of your neurons has three main parts – cell body, dendrites, and axon.

Meanwhile, glial cells or neuroglia mean “nerve glue.” They are connective tissue in the nervous system. Your neuroglia, unlike neurons, do not conduct signals. Instead, they offer support to neurons for their structure and function.

What is the main characteristic of nervous tissue?

Nervous tissue’s main trait is its unique excitability or irritability. This property refers to the ability of some cells. They can respond to changes or stimuli. These cells include neurons, muscle cells, and some gland cells. They show their ability to react. They do this by changing the ionic gradient. They do it across their plasma membrane in response to various stimuli.

When your neurons encounter stimuli, they undergo a rapid ionic gradient reversal. This process, known as membrane depolarization, spreads across the entire membrane. This depolarization wave is often called the action potential. It can travel long distances along the neuronal processes.

As it travels, it sends signals to other neurons, muscles, and glands. These help them communicate and coordinate within your body. This allows you to respond to signals. This plays a vital role in sensing, moving, and body functions. Additionally, specialized nervous tissue is amitotic. Once something destroys it, it cannot regenerate because it does not undergo mitosis.

What is nervous tissue made of?

Nervous tissue is integral to the function of the nervous system. Two distinct cells make it, neurons and neuroglia. The neurons in your body are the primary communicators within your nervous system. Meanwhile, neuroglia provides support and maintenance for neurons. It gives insulation, nutrients, and defense from pathogens.

Figure 1. Structure of a neuron.

The structure that supports your neuron has three main parts. These parts are the cell body, dendrites, and axon. The cell body, also known as perikaryon or soma, contains a nucleus with at least one nucleolus. But unlike other cells, it lacks centrioles due to the amniotic nature of the cell.

Dendrites, also known as fibers, receive stimuli from other neurons. In some cases, the soma receives signals. They have a tree-like structure extending from the cell body to receive neurotransmitters.

Neurons can differ in the number of dendrites they have. Some lack dendrites, while others have many. They may have dendritic spines. This help increase their surface area for connecting with other neurons. Also, dendrites transmit impulses to your body’s neurons, classified as afferent processes.

Axon also transmits signals away from the cell body to other neurons, muscles, or glands. It is a tube-like structure. It carries the processed signal to endpoints called axon terminals. Your neurons can have one or two axons.

Other structures of a neuron are synapse and axon hillock. A synapse is where two neurons come close together, allowing one neuron to send a signal to the other. One side has the axon terminal of the sending neuron. The other side has a dendrite or dendritic spine of the receiving neuron. A tiny gap, the synaptic cleft, is in the middle. One neuron releases neurotransmitter across it to the next neuron.

Meanwhile, the axon hillock is where a neuron begins an action potential. It also decides whether to generate one. Not every signal received by a neuron at a synapse triggers an action potential. A single neuron can get signals from thousands to hundreds of thousands of other neurons. Some may send conflicting messages at the same time. The neuron combines these conflicting signals. It “integrates” them at the axon hillock. The hillock is between the cell body and the start of the axon. The process at the axon hillock integrates signals. It decides if the neuron will generate an action potential.

Classification of Neurons

The classification of your neurons based on their structure:

• Multipolar neurons
  • It is the most common among all neurons. It consists of one axon and two dendrites.
  • Bipolar neurons
    • Areas such as the eye, nose, and inner ear contain it. It consists of one axon and one dendrite.
  • Unipolar or pseudounipolar neurons
    • This includes all sensory neurons. They have one main branch that splits near the body. One part goes to the body’s edges, while the other goes toward the CNS.
  • Anaxonic neurons
    • It consists of many dendrites but have no true axons. It does not produce action potential. Instead, they regulate electrical changes of adjacent CNS neurons.

The classification of your neurons based on their function:

• Sensory neurons
  • It is also known as afferent neurons and are unipolar. It is the receiving stimuli from the receptors throughout the body.
  • Motor neurons
    • It is also known as efferent neurons and are multipolar. It sends impulses to effector organs such as muscle fibers and glands. Some motor neurons manage muscles you can move, like those in your arms and legs. Meanwhile, others control automatic body functions such as heart rate and digestion.
  • Interneurons
    • It creates connections between other neurons, forming complex networks in CNS. These cells make up most of the neurons in your body and can either be multipolar or anaxonic.

Neuroglia or Glial Cells

Neuroglia in the mammalian brain is more abundant, being 10 times more common. In the CNS, these cells surround both the larger neuronal cell bodies. They also surround the axons and dendrites between neurons. CNS contains little connective tissue and collagen, except around your major blood vessels. It replaces connective tissue, supporting neurons and creating ideal spaces for neuronal activity. There are six major types of neuroglia located both in your CNS and PNS.

Neuroglia in Central Nervous System

• Oligodendrocyte
  • Named from the Greek’s words oligo, small; dendron, tree; kytos, cells. It extends processes around your CNS axons, creating myelin sheath for electrical insulation. They work together to wrap axons, speeding up nerve signals. Under light microscopy, your glial cells appear as small cells with rounded nuclei.
  • Astrocyte
    • Named for their star-like appearance, from the Greek words astro-, star; kytos, cells. It has several branching processes supported by glial fibrillary acid protein (GFAP). It serves as a unique marker for this type of glial cell. This cell functions as structural and metabolic support for neurons and repair processes.
  • Ependymal cell
    • It is a columnar or cuboidal cell found lining the fluid-filled spaces in your brain and spinal cord. The ends of some cells have cilia which helps the cerebrospinal fluid (CSF) to move. The long microvilli help with absorption.

• Microglia
  • These are small cells with many long, branching processes. In some areas of CNS, they are abundant as neurons. But they are not common like oligodendrocytes and astrocytes.

Neuroglia in Peripheral Nervous System

• Schwann Cell
  • It is also known as neurolemmocytes. It does similar things to oligodendrocytes in the CNS. This includes supporting axons and making myelin sheaths. Unlike oligodendrocytes, they wrap their myelin sheath around one part of the axon.
  • Satellite Cell
    • It is a small glia that surrounds the sensory ganglia of neurons in the autonomic nervous system (ANS). These cells provide structural and metabolic support for neuronal cell bodies. Also, they are responsive to injury and can worsen pathological pain.

What are the two most important organs of the nervous system?

The brain and spinal cord are the two key organs in the nervous system.

Figure 2. Structure of a human brain.

Your brain is part of the central nervous system (CNS). It serves as the command center. It directs cognition, memory, sensation, movement, respiration, temperature regulation, and all body functions. It communicates through both chemical and electrical signals that travel throughout the body. It regulates various processes, with the brain interpreting each one. While some messages stay in the brain, others travel through the spinal cord and nerves in your body.

The average adult’s brain weighs around 3 pounds and consists of approximately 60% fat. The remaining 40% is a mixture of water, protein, carbohydrates and salt. Unlike muscles, the brain consists of blood vessels and nerves.

Main Parts of the Brain and their Functions

• Cerebrum
  • It is the largest part of the brain and located at the front. It contains two main parts: gray matter, known as the cerebral cortex, and white matter in its center. The cerebrum controls movement initiation, coordination, and regulating temperature. It is also responsible for speech, thinking, reasoning, judgment, emotions, problem- solving, and learning. Apart from that, your cerebrum carries out functions related to your five senses.
  • Brainstem
    • Found in the middle of the brain, the brainstem connects the cerebrum to the spinal cord. It consists of three main parts: the midbrain, the pons, and the medulla.
  • Cerebellum
    • Often referred to as the “little brain.” It is a first-sized region situated at the back of the head. Also, the brain divides into two hemispheres. The outer part contains neurons, while the inner communicates with the cerebral cortex. Your cerebellum functions in coordinating voluntary muscle movements and maintaining posture.

Figure 3. Structure of a spinal cord.

Your spinal cord is a lengthy, tube-like structure wherein it is about 18 inches long in most adults. This organ links your brain to your lower back. It is a pathway for nerve signals. They travel between your brain and body for you to sense feelings and control movement. Any injury can impair your mobility or function.

Main Parts of the Spinal Cord

• Sacral cord
• Lumbar cord
• Thoracic Cord
• Cervical Cord
• Coccygeal

How many nerves are in the human body?

The body consists of seven trillion nerves, transmitting various signals throughout the body.

Every part of your body has nerves. Even the bones have many nerves. Your skin, especially on your fingertips and face. is the organ that contains many nerves. These parts are full of nerve endings, so it is very sensitive to touch and change in temperature.

Your nerves arise during embryonic development. This happens through a process called neurogenesis. Stem cells become precursor cells, which then mature into neurons. Throughout your life, neurons can change. They do so in response to both internal and external signals. They change by reorganizing their structure and functions. Like other cells, neurons also undergo degeneration. This leads to cell death, which contributes to neurological disorders.

How are the nervous tissues protected?

Nervous tissues have many protective mechanisms. The central and peripheral nervous systems protect it. They do this using anatomical structures. These include the skull, vertebral column, meninges, and cerebrospinal fluid (CSF).

The skull and the vertebral column’s bone structure is important. They provide a robust protective barrier for the brain and spinal cord. The skull has a strong bone. It encases the brain, shielding it from impacts and injuries. The vertebral column consists of a series of vertebrae. It surrounds and protects the spinal cord, ensuring its safety from physical trauma.

Also, three layers of connective tissue known as meninges wrap your nervous tissues. They serve as an extra protective layer. The outermost layer is the dura mater. It forms a tough and fibrous covering around the brain and spinal cord. It provides mechanical support and protection. Below your dura mater is the arachnoid mater. It is a membrane that cushions and supports nervous tissues. Finally, the innermost layer is the pia mater. It is a thin membrane that sticks to the brain and spinal cord. It gives extra support and nourishment.

Furthermore, CSF also protects nervous tissue. Your CSF fills the spaces within the meninges. It forms a fluid cushion that absorbs shocks. This fluid also helps keep a stable environment around your brain and spinal cord.

Moreover, endothelial cells form the blood-brain barrier. They line the blood vessels in the brain. The barrier controls the passage of substances from the blood into the brain. This stops harmful substances such as toxins and pathogens that enter the brain.

Why is our nervous system important?

The nervous system is vital for your functioning and survival.

The nervous system is key for coordinating body functions. It sends signals for movement, sensation, and more. It enables responses to touch, pain, and sound. You can sense these through touch, temperature changes, and sound. They contribute to your well-being. It also controls involuntary functions like heartbeat and breathing. It also handles voluntary actions like walking and thinking. Moreover, it maintains homeostasis by regulating physiological parameters.

References:

Admin. (2022, September 22). Spinal Cord – Anatomy, Structure, Function, & Diagram.

BYJUS. https://byjus.com/biology/spinal-cord/#structure

Admin. (2023, June 23). How many nerves are in the human body? Brain and Spine Specialists. https://brainandspinecenterllc.com/2023/06/23/how-many-nerves-are-in-the-human- body/#:~:text=Diving%20into%20the%20world%20of,to%20a%20body’s%20electrical% 20wiring.

Brain anatomy and how the brain works. (2021, July 14). Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-of-the- brain#:~:text=The%20brain%20is%20a%20complex,central%20nervous%20system%2C

%20or%20CNS.

Libretexts. (2023, January 17). 10.2B: Neuroglia of the Peripheral Nervous System. Medicine LibreTexts. https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiol ogy_(Boundless)/10%3A_Overview_of_the_Nervous_System/10.2%3A_Neuroglia/10.2 B%3A_Neuroglia_of_the_Peripheral_Nervous_System

Mescher A.L.(Ed.), (2021). Junqueira’s Basic Histology: Text and Atlas, 16e. McGraw-Hill Education.

Nerve         Tissue         |         SEER         Training.         (n.d.-b).                   Training.Seer.Cancer.Gov. https://training.seer.cancer.gov/anatomy/nervous/tissue.html

Neurons | Organismal Biology. (n.d.). https://organismalbio.biosci.gatech.edu/chemical-and- electrical- signals/neurons/#:~:text=Dendrites%20are%20tree%2Dlike%20structures,receive%20neurotrans mitters%20from%20other%20neurons.

Polis, B., & Samson, A. O. (2021). Neurogenesis versus neurodegeneration: the broken balance in Alzheimer’s disease. Neural Regeneration Research/Neural Regeneration Research, 16(3), 496. https://doi.org/10.4103/1673-5374.293138

Professional, C. C. M. (n.d.). Spinal cord. Cleveland Clinic. https://my.clevelandclinic.org/health/body/21946-spinal-cord

Puderbaugh, M., & Emmady, P. D. (2023, May 1). Neuroplasticity. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK557811/

Written by Angelica Mari Kiroquero

Reviewed by Dr. Reuben J C. los Baños, Ph.D.

Understanding the circulatory system is a crucial step in understanding oneself.

Blood and blood cells are being pumped and managed by the circulatory system. It carries the blood to all the tissues in your body. Did you know that the total length of an adult’s blood vessel, in estimation, is between 100,00 and 500,00km?

Cells that are similar in structure work together to perform specialized functions. These are what we call tissues.

The circulatory system consists of many structures and comprises different tissues. The heart consists of cardiac muscles and epithelial and connective tissues.

The heart plays a vital role in our lives because it handles many body functions. Some may say the heart is a shape in the color red, but it is not a shape, nor is it inside of your body for the reason of loving. Let’s learn more about the heart and its function!

The main functions are pumping blood, supplying oxygen, and removing metabolic wastes. Amazing, right? The human body is capable of doing wonders. Some of you might also know this, but the size of your fist is the average heart, which is the size of a heart.

Now, try clenching your fist and find out the size of your heart!

Before we delve deeper into the circulatory system, Let’s discuss what makes up the heart. It will help you understand its significance to humans as long as we live.

Cardiac muscles compose a heart wall that divides into four chambers that help the body pump blood. The two upper chambers of your heart are the atrium, and the two lower chambers are the ventricles. The septum is an internal heart wall that divides your heart into the left and right.

On the upper chambers, your right and left atria act as intersections or junctions on the road. They receive blood from different body parts and the pulmonary veins. The redistribution of the blood throughout the parts is also done after receiving it.

The lower chambers are in charge of your pulmonary and systematic circulations. It is like pumping chambers, pumping blood while providing proper circulation. It circulates the blood like the motor pistons that allow fluid movement.

The composition of the heart does not end here, as it is a very complex organ as much as its importance. It comprises many chambers, veins, and arteries that work together to function.

Surrounding the heart is the pericardium. A fibrous, fluid-filled sac lined by a serous mesothelium as the protective layer.

It comprises the Fibrous pericardium (outer layer) and Serous pericardium (inner layer). Your serous pericardium is further divided into the parietal and visceral layers.

Three significant layers divide the heart walls’ four (4) chambers. The layers are the internal endocardium, the middle myocardium, and the external epicardium.

Endocardium

The lining endothelium comprises the internal endocardium or tunica intima. “Endo” is defined as internal or within. The name already suggests that it is the innermost layer wall of your heart. It is lining inner surfaces, such as heart valves.

Connective tissues, a fibroblastic layer with smooth muscle cells, and a subendocardial layer support them.

The subendocardial layer is a connective tissue that contains an impulse-conducting system. Conducts electrical impulses in your heart that contain specialized cardiac cells.

What is the thickest histologic layer of the heart?

Myocardium

Known as tunica media, it is the middle and muscular layer. The contractional function for blood pumping happens here and is considered the principal functional element.

Cardiomyocytes comprise the myocardium and generate the contractile force. Like us humans, communication is essential; we communicate using language. Intercalated discs are a unique intercellular bridge for their communication.

Did you know that cardiomyocytes are like cells found in the skeletal muscle? These are myocytes containing similar striations. Yet these cardiomyocytes are branching mononucleated containing intercalated disks.

The number of nuclei differentiates it from skeletal muscles.

It may contain varying amounts of elastic fibers, smooth muscle cells, and collagen fibers.

It is arranged spirally in a contractile cardiac muscle fibers chamber—the thickest layer due to the strong force needed to pump blood in circulations. The thickness varies in each location, for ventricles are denser than in the atria.

The atria are thinner due to the passive blood flow. The left ventricle requires the production of enough force to propel blood in circulation. This explains why its wall is thicker than the right ventricle.

What is the histology of the heart epicardium?

Epicardium

It is made up of simple squamous mesothelium and supported with a layer of loose connective tissue containing blood vessels and nerves. The membrane surrounding the heart is a visceral layer of the serous pericardium.

During heart movements, the;

• Adipose tissue(epicardium) cushions the underlying structures.
• Production of lubricant fluid by both layers of the serous mesothelial cells. The fluid prevents friction within the pericardium.

The pericardium subdivides into;

• The fibrous layer is comprised of many fibrous connective tissue.
• The serous layer. Contains an inseparable outer layer(fibrous pericardium) and an overlying inner (myocardium )layer.

What is the histology of the blood and blood vessels?

Blood is fluid connective tissue, while the endothelial cells line the blood vessels. The vessel’s size and job determine how much connective tissue and smooth muscle are in its wall.

Blood vessels are channels that carry blood throughout your body. Think of a road system with different vehicles. The roads and highways are the blood vessels, and the cars traveling are the blood.

Blood vessels are further divided into three parts. They are your Arteries, veins, and capillaries.

Arteries

The blood vessels that carry oxygen-rich blood to your body are your arteries. The main functions are the management of oxygen, nutrients, and hormone transportation in your body.

Transporting blood is done not only by the arteries themselves but by your heart! Your heart pumps the blood into your aorta, the most prominent artery.

There are two types of arteries: elastic (aorta and pulmonary) and muscular (Femoral, radial, and brachial arteries.

Veins

Veins are the collectors! Located throughout your body, it is in charge of returning oxygen-poor blood after its collection.

Another function is carrying oxygen-rich blood to the heart coming from your lungs. Did you know that during this cycle, it is the only time they contain oxygen-rich blood?

Although they function similarly, arteries have thick walls with muscle tissue, while veins use valves and thinner walls to keep your blood flowing throughout the body.

Capillaries

Capillaries are the smallest and most delicate type of blood vessel in your body; due to their small and narrow size, only a single line of substances can pass through at a time.

This medium transports cells, nutrients, and oxygen throughout your body. It is a connector for the veins and arteries to complete the circulatory system.

What is the histological structure of the heart valve?

Before the blood can leave each chamber, it has to pass through a valve. A valve is like your water faucet; it controls the water flow as valves control the flow of blood passing through each chamber.

When the valve opens, it allows blood to pass through, but when it closes, it prevents blood from leaving or returning to the other chamber.

Each aortic valve comprises three leaflets (cusps) made mainly of collagen; the valve is placed on a muscle ring and connected to the heart wall.

The valves usually occur in this sequence:

• As the left ventricle relaxes, the mitral valve opens once the aortic valve closes. This allows the flow of blood from your left atrium into the left ventricle.
• Contraction of the left atrium occurs, which allows more blood flow into your left ventricle.
• The mitral valve closes, and the aortic valve opens as soon as the left ventricle contracts, allowing blood to flow into the aorta and out to the rest of your body.
• Your left and right ventricle relax and cause the tricuspid valve to open and the pulmonary to close. Allowing blood to flow into the right ventricle that had returned to the right atrium from the body.
• Your left and right ventricles contract and open and close the pulmonary and tricuspid valve, respectively. Blood flows from the right ventricle to the lungs and then returns to the left atrium as fresh, oxygenated blood.

An extracellular matrix highly organizes valves into layers. Arranged according to the flow of your blood.

The semilunar valves carry blood away from the heart to pulmonary and systemic circulations—the two valves are pulmonary and aortic.

The semilunar valves divide into:

• Ventricularis – direct contact with pulsatile blood and directed toward the ventricles.
• Spongiosa located between the ventricularis and fibrosa layers. It is made of proteoglycans with collagen fibers.
• Fibrosa directs toward the outflow vessel lumen.

Atrioventricular valves are like the semilunar valves. But, they have a layer called the ventricularis. It allows blood to flow from the atria into the ventricles.

It has two valves. Each valve lies between an atrium and a ventricle. The right atrioventricular valve (tricuspid valve) and left atrioventricular valve (mitral valve). A ring surrounds the orifice, with two or three cusps lining the valves.

The layers of the atrioventricular valves arrange themselves in a way that:

• The atrialis.
• The spongiosa located in the middle.
• The fibrosa layer is directed toward the ventricles.

A sheath of endocardial endothelial cells interlaced with valve interstitial cells encases each layer of the valves.

The four valves of the heart are aortic, mitral, pulmonary (or pulmonic), and tricuspid.

As the name suggests, the aortic valve allows blood to flow from the heart’s left ventricle to the aorta. It distributes oxygen-rich blood from the heart to other parts of your body and is the final destination encountered by oxygenated blood before it leaves the heart.

Located in between your left ventricle and aorta, when facing the heart it is located near the middle of your heart. For healthy individuals, the leaflets allow blood flow by opening wide and clasping tightly to prevent the backflow of blood.

In some cases, some individuals may be born with only two leaflets. A bicuspid aortic valve is called if it only consists of two leaflets.

Similar in function to the valves but different in structure. The mitral valve or left atrioventricular valve, has two leaflets, while the others have three leaflets. The leaflets are referred to as the anterior leaflet and the posterior leaflet.

They allow blood to flow from your left atrium to your left ventricle and prevent backward flow. This valve ensures the blood flows in the proper direction as it opens and closes. It is located in between the upper left chamber of your heart and the lower left chamber.

Now, let’s recap: the upper-left chamber is the left atrium, and the lower-left chamber is the left ventricle.

Your pulmonary valve helps manage blood flow and controls the flow of oxygen-poor blood from your heart to your lungs. Once your blood enters your main pulmonary artery, it travels to your lungs from your left and right pulmonary arteries.

The main function of your pulmonary valve is managing the blood from your right ventricle into your main pulmonary artery. However, it manages oxygen-poor blood.

Located on the right and in front of your aortic valve. Your pulmonary artery passes through the arch of the aorta as it carries your blood to the right and left lungs.

Lastly, the tricuspid valve ensures that blood flows to your right ventricle from the right atrium. Like the other three valves, it also prevents blood from backflowing to the different chambers.

As the blood reaches the right atrium and fills it up, it is allowed into the right ventricle as the tricuspid valve opens up. Contraction of the right ventricle provides blood to follow to the lungs. The tricuspid valve closes tightly to avoid backflow.

As your heart beats, the sound comes from the leaflets. The opening and closing of valves make up the sound of your heartbeat!

References:

Anatomy, arteries. (2024, January 1). PubMed. https://pubmed.ncbi.nlm.nih.gov/31613523/#:~:text=Arteries%20make%20up%20tubelik e%20structures,and%20hormones%20through%20our%20bodies.

Arackal, A., & Alsayouri, K. (2023a, January 2). Histology, heart. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK545143/#:~:text=Valves%20have%20three%20 layers%3A%20spongiosa,arterial%20side%20of%20semilunar%20valves.

Arackal, A., & Alsayouri, K. (2023b, January 2). Histology, heart. StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK545143/#:~:text=The%20subendocardium%20 is%20found%20between,electrical%20impulses%20throughout%20the%20heart.

Crawford, P. T., Arbor, T. C., & Bordoni, B. (2023, September 4). Anatomy, thorax, aortic valve.

StatPearls – NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK559384/#:~:text=The%20aortic%20valve%20i s%20one,back%20into%20the%20left%20ventricle.

Heart valves. (2023, August 31). Kenhub. https://www.kenhub.com/en/library/anatomy/heart-valves

Layers of the heart. (2023, November 3). Kenhub. https://www.kenhub.com/en/library/anatomy/layers-of-the-heart

Libretexts. (2023, January 17). 17.1F: Myocardial thickness and function. Medicine LibreTexts. https://med.libretexts.org/Bookshelves/Anatomy_and_Physiology/Anatomy_and_Physiol ogy_(Boundless)/17%3A_Cardiovascular_System%3A_The_Heart/17.1%3A_The_Heart

/17.1F%3A_Myocardial_Thickness_and_Function#:~:text=The%20myocardium%20is% 20thickest%20in%20the%20left%20ventricle%2C%20as%20this,aorta%20and%20throu ghout%20systemic%20circulation.

Mescher, A. L. (2013). Junqueira’s Basic Histology: Text and Atlas. https://ci.nii.ac.jp/ncid/BB2696515X

Mmts. (2016, July 27). The heart: a complex system of the human body. Minnesota Medical Training Services. https://www.minnesotacpr.com/heart-complex-system-human-body/

Myers, J. (2022, October 6). Aortic valve: what to know. WebMD. https://www.webmd.com/heart/aortic-valve-what-to-know

News-Medical. (2022, September 5). Structure and function of the heart.

https://www.news-medical.net/health/Structure-and-Function-of-the-Heart.aspx#:~:text= As%20the%20central%20part%20of,the%20tissues%20in%20the%20body.

Paxton, S., Peckham, M., & Knibbs, A. (2003). The Leeds Histology Guide. https://www.histology.leeds.ac.uk/circulatory/circ_common_str.php

Professional, C. C. M. (n.d.-a). Arteries. Cleveland Clinic. https://my.clevelandclinic.org/health/body/22896-arteries

Professional, C. C. M. (n.d.-b). Capillaries. Cleveland Clinic. https://my.clevelandclinic.org/health/body/21988-capillaries

Professional, C. C. M. (n.d.-c). Pericardium. Cleveland Clinic. https://my.clevelandclinic.org/health/body/23561-pericardium

Professional, C. C. M. (n.d.-d). Pulmonary valve. Cleveland Clinic. https://my.clevelandclinic.org/health/body/24273-pulmonary-valve

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Vega, J., MD PhD. (2023, September 1). What are brain ventricles? Verywell Health. https://www.verywellhealth.com/brain-ventricles-3146168

Written by Kylemaxinne Panzo

Reviewed by Dr. Reuben J C. Los Baños, Ph.D.

Muscles are the tissues all around the body that allow you to move because of their ability to contract. They can be generally categorized into different types based on morphology and function. Smooth muscles, also called non-striated muscles, involve slow and involuntary movement.

Imagine yourself in the gym, you may only be thinking about the skeletal muscles in your arms or legs. But there are also the muscles working hard in your lungs and blood vessels when you breathe. Smooth muscles are essential in hollow organs for such activities.

In the digestive tract, the wave-like motion called peristalsis occurs to propel food. Smooth muscles in the esophagus, stomach, and intestines are responsible for peristalsis. They also mix food and digestive juices into smaller particles to absorb nutrients.

Smooth muscle forms the middle layer of blood vessel walls. Constricting (vasoconstriction) or dilating (vasodilation) these muscles can change their diameter. In this way, regulation of blood pressure is possible.

Smooth muscles in the bronchi and bronchioles also control airflow. Their constriction (bronchoconstriction) triggers coughing and shortness of breath. Relaxing these muscles (bronchodilation) leads to easier breathing in asthma and COPD.

In the urinary bladder, smooth muscles expand as it is being filled. They also excrete toxins and regulate the balance of electrolytes. Smooth muscles are also used in the uterus during pregnancy and the movement of the sperm.

Smooth muscles are also in the eyes and the skin. In your eyes, they function to change the size of the iris and the shape of the lens. In your skin, they cause hair to stand straight when exposed to cold or when in fear causing goosebumps.

All things considered, smooth muscles serve vital purposes all over your body. They help to maintain homeostasis, transport chemicals, and regulate organ function.

What is the difference between smooth and skeletal muscle?

The main difference between smooth and skeletal muscles is in whether we can control them or not.

Smooth muscles are involuntary muscles found within the body, especially in the organs. This helps in proper digestion, nutrition, and the balance of waste and toxins in the body.

At the same time, skeletal muscles are voluntary muscles found in the bones. This aids humans to move, this also helps in posture, balance, and protecting organs in the body.

Smooth muscles often contract slower allowing them to sustain more fatigue. This is due to its pacesetter cells, latch-bridge, and cross-bridges that need low ATP. So, skeletal muscles contract longer due to the force produced by their motor units.

The cells in smooth muscles are non-striated, while skeletal muscles have striations. In the microscope, smooth muscles are not striated since they do not have sarcomeres. The striation of the skeletal muscles is due to its actin and myosin filaments.

Under the microscope, smooth muscles have one nucleus and skeletal muscles have many. Many nuclei allow the skeletal muscles to gain more oxygen to be able to do work and contractions. While single nuclei aid the metabolic demands of the smooth muscle within the body.

The central nervous system controls the skeletal muscle hence allowing voluntary movements. Smooth muscle is involuntary and controlled by the autonomic nervous system. This allows the muscles to perform both movement and metabolism for the body.

A good example of this voluntary and involuntary movement is through running. When we run, the movement of our feet and their pace is a voluntary movement caused by the skeletal muscles. The respiration that we do is an involuntary movement caused by smooth muscles in the lungs.

In conclusion, smooth muscles are non-striated, involuntary muscles found in our organs. While skeletal muscles have striations and we can find them in our bones. Both aid the body with primary functions that are essential for our daily survival.

How does smooth muscle contract?

The contraction of smooth muscles controls the heart, lungs, and other organs. This happens through reactions in our body controlled by electrical and chemical signals. Without this, we would not be able to breathe or metabolize things in our bodies.

Calcium controls the contraction of the smooth muscles. This reaction happens when calcium binds with calmodulin and activates enzymes for contraction. Calcium channel regulation allows our muscles to relax when calcium is not present.

To start contraction, depolarization needs to happen since this opens the calcium channel. When the channels open, calcium ions can enter the system, bind, and activate enzymes. The enzyme is from the activated myosin light chain kinase when a high amount of calcium enters.

The myosin light chain adds a phosphate group to the myosin that allows it to bind with actin. This action will result in the cross-bridge formation of actin and myosin and will turn into a cycle. Hydrolysis of ATP also happens which activates the contraction of smooth muscles.

Contractions are also affected by factors such as tension and length of the muscles. Length-tension relationship allows smooth muscles to contract longer. Since there is less tension because of their loose arrangement within our body.

When our organs are empty smooth muscles maintain it through muscle tone. Powered by the myosin light chain kinase, slow contractions aid muscle toning. This is vital so that organs would not fail their function and return to their normal state when not used.

Smooth muscle contraction happens due to the myosin light chain kinase reaction. Without this, natural reactions of the body such as metabolism will not happen. Thus, if there is no contraction in our smooth muscles, this will affect the state of our body and organs.

What happens when smooth muscles relax?

Our smooth muscles also need to return to their normal state through relaxation. This happens when myosin removes a phosphate group in the myosin light chain kinase. This is essential for regulating blood pressure and metabolism in our body.

To dig deeper, relaxation starts with the reduction of calcium in the gated channels. When there are lower calcium ions binding for conformational changes is not possible. Hence this would not activate calmodulin and the other enzymes of contraction.

To remove the phosphate group, myosin undergoes the myosin light chain phosphatase. This regulates the reduction of actomyosin-based contractility. This allows the contraction to be undone and the smooth muscles of the body to relax

During relaxation, muscle tone also happens and it’s maintained when phosphorylation is low. This relaxation is important for organ systems such as the urinary system. This allows the bladder to relax which is vital in storing urine in the body.

Smooth muscle relaxation is also triggered by hormones and neuron signals. Neurotransmitters such as Nitric oxide diffuse in our muscle cells for it to relax. While hormones like progesterone affect nitric oxide levels for muscle relaxation.

Smooth muscle relaxation is important for the following actions:

1. Smooth muscle flexibility: our body needs to adapt to the changes. Continuous contraction of muscles stops actions like breathing and blood pressure control.
2. Stimuli Response: Relaxed smooth muscles help in quick cell communication. This allows our body to respond to stimuli immediately.

Relaxation of the smooth muscles has benefits for the body’s health. These health benefits revolve around proper organ function and cell response. Which ensures that our body is well for everyday functions.

Indeed, smooth muscle relaxation is also an important function of the muscles in our body. This happens through various processes from low levels of calcium, to neurotransmitter signals. But, this can also only happen with the aid of contraction in the muscles of the body.

Are smooth muscles multinucleated?

No, smooth muscles are not multinucleated.

When observed under the microscope, you will see a single nucleus within each cell. In comparison, when we observe skeletal muscles we can see that they have many nuclei in their cells.

The smooth muscles also have a cigar-like shape for their nucleus, as seen with the tapered ends of the shape. This shape of the nucleus influences the contraction that happens in the muscle of an organ. Since it helps in the diffusion of ions in the cells and the quick response to chemical triggers.

Besides the shape, the nucleus location of smooth muscle is vital for cell integrity. The presence of the nucleus at the center allows it to adjust to the high metabolic demands of the body. A centered nucleus opens space for more protein production, especially for muscle tissue.

Smooth muscles are homogenous when observed under the microscope because of their nucleus. It is also important that these cells are homogenous as they perform the same function in organs. An example of this is when smooth muscles are in the lining of the lungs which act for respiration.

Additionally, the smooth muscle also has many myosin and actin proteins. This is possible due to the single nucleus of the cells which gives more space for proteins in the cell. Hence these proteins that are key for contraction help the cells to maintain muscle tone.

These smooth muscles can’t have many nuclei since it will permit more fatigue. During contraction and relaxation processes, muscles need a lot of protein. If the cells have many nuclei it won’t be able to produce the amount of protein to sustain the muscle demands.

The single nucleus is also essential for the regulation and adaptation of cells. This allows the efficient regulation of gene expression in the muscles. This is vital for specific functions like digestion, blood pressure changes, and breathing.

Generally, the single nucleus of smooth muscles allows for its cells to communicate. It’s needed for protein production, and gene expression for muscle to handle fatigue. Without it, functions such as breathing and digestion are not possible in the body.

Can we control smooth muscle?

As we know, we can observe the functions of smooth muscles from digestion to breathing. These actions are often involuntary since we cannot control smooth muscles. The autonomic nervous system controls the smooth muscles hence actions are unconscious decisions.

The autonomic nervous system releases hormones and neurotransmitters for smooth muscles. These things serve as a stimulus that the smooth muscle receives. An example is norepinephrine which allows muscle spasms in the vascular walls.

Going deeper, two divisions help the smooth muscle:

1. The Sympathetic System: This releases neurotransmitters which are vital for organ wall function.

• The Parasympathetic System: This system controls the muscles needed for organ support.

We cannot control smooth muscles because of neurotransmitters. These act as signals where smooth muscle response for contraction and relaxation. Examples of these are acetylcholine and norepinephrine.

Most of the time organs in the body use these signals to start certain reactions or functions. For example, glandular secretion is only possible when there is a neurotransmitter. Since this sends a signal for the release of these substances.

There are also two types of smooth muscle present in the body. These are the single-unit and the multi-unit smooth muscle. Both have specific and independent functions in the body.

• Single-unit smooth muscles have connexins that allow the connection of many cells. This single connection also allows the one synaptic input of these cells. These are often found in the walls of hollow organs and reaction is through gap junctions.
  • Multi-unit smooth muscles do not have a single series for one synaptic input. Each cell of this muscle unit receives the synapse for a more controlled reaction. These are often in the muscles of the eye, arteries, and airways of the lungs.

Besides internal stimuli, there are also external factors that affect smooth muscle function. Things such as temperature, pressure, and chemical composition affect the body. This affects how smooth muscle adapts to maintain homeostasis in the body.

For example, during a drop in temperature, the contraction of smooth muscles slows. This is because of the lack of tension since force is lower when there is a lower temperature. This forces the release of transmitters to balance the change in the environment.

The autonomous nervous system and external factors influence the action of muscles. Since smooth muscles are involuntary, they rely on the triggers in the environment. These triggers allow response so the body and organs remain functional.

What happens when smooth muscles don’t work?

Imagine if one day our smooth muscle stops functioning, what do you think will happen in our body? It is important to understand that the dysfunction of smooth muscles is a threat to our body. It puts our health and our safety at risk since it affects major organs like the heart and the lungs.

Smooth muscles allow respiration in our body, it cannot be dysfunctional. These cases will impair the lungs and hence will lead to respiratory problems. Major examples are asthma-like symptoms since the bronchi and alveolar will be close.

Problems in smooth muscles affect the gastrointestinal tract. Since it handles the lining of the organ that allows muscle toning for digestion. Without it, propelling bolus from what we intake would not be possible.

This can also lead to discomfort and digestive problems. Smooth muscles control the intestine to prevent situations like diarrhea. Smooth muscle problems in the arteries and vessels can also impair the function of the heart.

Smooth muscle dysfunction also affects the urinary and reproductive systems. It can cause urinary incontinence or the unintentional release of urine. It can compromise uterine contraction and fetal delivery.

In conclusion, smooth muscles are crucial for organ function and balance in the body. Compromised muscles lead to complications and it affects many parts of the body. Hence this puts us at risk, especially our health and functionality for every day.

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Hafen, B. B., Shook, M., & Burns, B. (2023). Anatomy, Smooth Muscle. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK532857/

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The article is developed in partnership with BetterHelp

Life is full of ups and downs, and it’s normal to face struggles from time to time. Whether it’s stress at work or school, difficulties in relationships, or emotional challenges, most of us can find ways to cope.

Usually, we can bounce back on our own, but sometimes we need extra support and could benefit from seeking therapy with a trusted mental health professional. This can be especially true for college students as they experience all the excitement, transition and stress associated with this time of life.

So how do you know if therapy is the right step for you? Therapy can be a powerful tool for improving mental health and overall well-being. Unfortunately, there’s often a stigma associated with seeking therapy, and many people may not realize when it could be good for them.

Let’s look at some of the factors that might indicate you could benefit from working with a trusted and knowledgeable mental health professional.

The State of Mental Health on College Campuses

As recently as 2022, 77 percent of surveyed college students reported experiencing some level of mental health distress. Of those, 35 percent were diagnosed with anxiety and 27 percent reported experiencing symptoms of depression.

Student respondents also reported high levels of stress, feelings of loneliness and suicidal ideation. So, if you’re a college student experiencing psychological distress, you’re certainly not alone.

Common Signs You Could Benefits from Therapy

While everyone is different, some of the signs listed below are common among those who are struggling with difficult issues and could use an outside perspective:

Difficulty expressing yourself – If you frequently think, “I wish I had the words for this,” or “I need to talk this out more,” therapy could be a good step. A trusted therapist can provide a safe space for you to explore and process your emotions, ultimately helping you gain clarity and insight.

Increased irritability or mood changes – Changes in mood or behavior could indicate that something deeper is going on. Therapy can help you identify the underlying causes of these changes and develop coping strategies to manage them more effectively.

Feeling like you’re not functioning at your best – If you feel like you’re not performing at your usual level – or you’re struggling to complete everyday tasks – therapy may be helpful. A change in your ability to function could indicate underlying issues that therapy can address. Whether its difficulty getting out of bed, feeling overwhelmed by daily responsibilities, or struggling to develop an effective study schedule, therapy can provide support and guidance.

Needing a confidential outlet – While friends and family can offer support, sometimes you need a confidential and unbiased space to feel like you can fully express yourself. Therapy provides a nonjudgmental environment where you can explore your thoughts and feelings without fear of judgment. And a therapist can offer insights and perspectives that friends or family may not be able to provide.

Feeling stuck or repeating patterns – If you feel like you’re stuck in a rut or repeating the same unhealthy patterns, therapy can help break the cycle. A therapist can help you explore the causes of your behaviors and develop strategies for change. Whether you need help overcoming self-destructive habits or improving your relationships, therapy can help you feel more empowered. A good therapist can help you identify the areas where you have agency over your own life.

Overwhelm and stress – Feeling overwhelmed by life’s challenges is common, and this may never be truer than during your college years. But if you’re struggling to cope, therapy may be able to provide the support you need. A therapist can help you identify your key sources of stress and develop coping strategies to manage overwhelming emotions. Learning effective stress management techniques can improve your overall well-being and quality of life – not just while you’re in college, but for the rest of your life.

Struggling with expectations – High achievers and perfectionists may struggle at times with unrealistic expectations, leading to feelings of constant pressure and dissatisfaction. These feelings are all too common on college campuses. But therapy can help you explore and challenge your own unreasonable expectations, helping you develop a healthier mindset and a level of self-compassion. By learning to set boundaries and prioritize self-care, you can achieve a better balance in life.

Anticipating or dealing with major life changes – Major life transitions, such as starting college, beginning a new job, moving, or experiencing loss, can be challenging to navigate alone. Therapy can provide guidance during these transitions, helping you cope with uncertainty and adjust to change. By exploring your thoughts and emotions in therapy, you can develop resilience and adaptability to face life’s ups and downs.

Processing trauma – Experiencing trauma can have long-lasting effects on mental health and well-being. Therapy offers a safe and supportive space to process trauma, explore its impact and develop coping strategies.

Addressing relationship dynamics – Difficulties in relationships, whether with family members, partners, or friends, can cause significant distress. And the relationships you develop while in college can feel particularly intense. Therapy can give you a neutral space to explore and address relationship dynamics, improve communication, and set healthy boundaries.

Managing physical health conditions – Physical health conditions can take a toll on mental well-being and vice versa. Therapy can complement medical treatment by helping manage the emotional and psychological aspects of a health condition. Therapy can provide valuable support and coping techniques for everything from chronic pain to adjusting to a new diagnosis or managing the stress of illness.

Understanding Distress and Interference
In addition to the factors listed above, two key indicators can help you decide whether you could benefit from therapy: distress and interference.

Let’s break down what this mean and how they can guide your decision.

Distress

• Do you find yourself thinking about the problem frequently?
• Is the issue embarrassing or causing you to hide from others?
• Has the problem significantly reduced your quality of life over time?

Interference

• Is the problem consuming a considerable amount of your time each day?
• Have you had to scale back on work or educational goals because of the problem?
• Are you rearranging your lifestyle to accommodate the issue?

If you answered “yes” to any of these questions, it might be a good time to consider seeking professional support. And it’s OK to ask your friends and family members about their answers to the questions above. It’s important to acknowledge that sometimes, a problem may seem less severe to you than it does to those around you. However, their concern could indicate that the issue is more significant than you realize.

In addition, below are 10 signs mental health experts say indicate it might be time to seek professional help:

• Difficulty regulating emotions: Feeling consistently sad, anxious, or angry.
• Decreased performance: Struggling at work or school due to mental health issues.
• Changes in sleep or appetite: Significant disruptions in sleeping patterns or eating habits.
• Relationship struggles: Difficulty building or maintaining relationships.
• Past trauma: Unresolved trauma affecting daily life.
• Loss of interest: Losing interest in activities you once enjoyed.
• Grieving: Difficulty coping with significant losses.
• Physical health impact: Mental health issues affecting physical well-being.
• Desire for self-improvement: Wanting to change but unsure where to start.
• Substance use or risky behaviors: Using substances or engaging in risky behaviors to cope.

Next Steps

Deciding to pursue therapy is a personal choice, but it’s key to remember that help is available. With advancements in psychological treatment, many therapy approaches have been scientifically proven to be effective, even in the short term.

Plus, there’s a wide range of therapeutic options available, allowing you to find an approach that works for you.

Most college campuses offer free or low-cost therapy options for students. Your college’s counseling center may offer free counseling for a set number of sessions or semesters. If you need more than that, they may be able to refer you to off-campus mental health professionals.

You may be able, through your college’s counseling center, to enroll in either individual or group therapy, workshops, and support groups. Besides this, some colleges offer teletherapy or online counseling services, which can be helpful for students who are unable to attend in-person sessions.

It’s important to remember that these services are offered in the strictest of confidentiality. Mental health professionals on college campuses are bound by strict ethical and legal standards that require them to maintain their clients’ privacy.

All information shared during therapy sessions, including personal details and concerns, must be kept strictly confidential and cannot be shared with anyone without a student’s written consent. The only exceptions to this rule are when a student poses a threat to themselves or others or the therapist is required by law to disclose information.

If you’re ready to take the next step, here are some ways you can get started:

Educate yourself: Learn about different therapy approaches to find one that aligns with your personality and needs. You can use online resources to find therapists specializing in your needs. You can also talk to someone at your college’s counseling center about what types of therapy are offered on campus.

Seek recommendations: Ask for recommendations from people you trust, including health care providers.

Reach out: Don’t hesitate to contact a therapist and schedule an initial consultation to discuss your concerns. Try to talk with multiple therapists and ask questions to gauge your compatibility.

Remember you’re not alone: Many people benefit from therapy, and taking this step is a sign of strength and self-care. If it’s helpful, try to talk with people on your campus who have benefitted from therapy. They can help you understand what the process is like and how it helped them.

Understanding Your Therapy Options
Many people misunderstand therapy, thinking it applies only to people experiencing severe mental health conditions. But talk therapy can be helpful for anyone dealing with stress, intense emotions, or life transitions.

Working with a therapist provides a safe space to process your thoughts and feelings, gain insight and learn coping skills.

Types of Psychotherapy

There are various types of therapy you can pursue, each suited to different needs. Many of these types of therapy approaches are offered on college campuses. And if you need a particular type of therapy that isn’t offered on your campus, your campus counseling center may be able to refer you to a nearby provider.

• Interpersonal psychotherapy: This type of therapy focuses on improving relationships and social functioning.
• Psychoanalytic psychotherapy: This approach addresses psychological disorders like depression and Post-Traumatic Stress Disorder.
• Cognitive analytical therapy: With this type of therapy, a therapist will help you examine past behaviors and frame better choices for the future.
• Systemic psychotherapy: This approach seeks to analyze relationship dynamics – it is often used in couples’ therapy. You might also see this as family systems therapy, since it focuses on the family unit and aims to help people resolve challenges within that context.
• Humanistic therapy: Humanistic therapy aims to help patients develop self-awareness and personal growth.
• Group therapy: In a group therapy setting, a counselor will work with a group of individuals who are experiencing the same type of mental health condition. This approach allows participants to listen to and learn from other people in the group.
• Cognitive behavioral therapy: One of the most effective treatment options, CBT helps people change behaviors and thoughts for better functioning.
• Neurofeedback therapy: This approach helps patients learn to change the way their brains respond to certain stimuli.

Find out more here about the various types of therapy you might consider and the benefits of each:https://www.betterhelp.com/advice/therapy/what-are-the-most-commonly-used-types-of-psychological-therapy/.

It’s important to note that many of these types of therapy can be delivered not only in person, but also virtually. And research indicates that therapy delivered through online platforms is equally effective as in-person therapy for most patients. Talk with your school’s counseling center to find out more about online therapy options.

Your Key Takeaway

Struggling with life’s challenges is absolutely normal, but when those struggles become overwhelming, seeking professional help can provide much-needed support and guidance.

And while the transition from high school to college is an exciting rite of passage, for many students it also represents a time of uncertainty, stress, and adjustment, which therapy can help address.

By recognizing the signs that therapy might be beneficial and taking proactive steps to support your own mental health and well-being, you can take control of your circumstances and work toward a happier, healthier life.