Activity 5 – The Digestive System 🔬🎨

The digestive tract, or the gut, plus additional organs including the stomach, pancreas, and gallbladder comprise the digestive system. It is the area where your body absorbs nutrients and minerals and breaks down food. The digestive system is a long, twisting tube that begins at the mouth and goes through the esophagus, stomach, small intestine, large intestine and ends at the anus part. Food is broken down by this system into basic components like proteins, lipids, and carbohydrates. Your body can then employ them for energy, development, and repair after they are absorbed into your blood. Meanwhile, everything that isn’t utilized by the body becomes waste and exits the body as feces or stool.

[1] Large Intestine Human c.s.

Structure: The colon, rectum, anus, and caecum are the four main divisions of the large intestine. The ileocecal valve regulates the movement of chyme from the small intestine into the large intestine and it is situated at the opening between the ileum and the large intestine. The appendix to the anus is where the large intestine ends. The small intestine is framed on three sides by it. It is named large even though it is only half as long as the small intestine because it has a diameter of around three inches, more than twice that of the small intestine.

Function: The alimentary canal’s terminal segment is the large intestine. This organ’s major functions include completing the body’s absorption of water and nutrients, synthesizing particular vitamins, generating feces, and removing them from the body.

[2] Ileum Human c.s

Structure: The ileum, which is approximately 1.8 meters (6 feet) long, is the longest segment of the small intestine. Compared to the jejunum, it is thicker, more vascular, and has more developed mucosal folds. At the ileocecal sphincter (or valve), the ileum connects to the caecum, which is the first segment of the large intestine.

Function: Food that has passed through the stomach and other sections of the small intestine is further broken down by the ileum. It absorbs any remaining nutrients, with the primary absorptive products generated such as bile acids and vitamin B12.

[3] Human Stomach-Cardiac c.s.

Structure: The stomach is divided into four main sections: the cardia, fundus, body, and pylorus. Food enters the stomach through the cardia, also known as the cardiac region, which is the junction of the esophagus and stomach. The dome-shaped fundus is situated above and to the left of the cardia, inferior to the diaphragm. The stomach’s primary portion, the body, is located beneath the fundus. The duodenum and stomach are joined by the funnel-shaped pylorus. The pyloric antrum, the funnel’s broader end, joins the stomach’s body. The pyloric canal, on the other hand, which joins the duodenum, is the narrowest end. At this final junction, the smooth muscle pyloric sphincter regulates the process of emptying the stomach. In addition, the stomach shrinks inward in the absence of food, causing the mucosa and submucosa to collapse into a sizable fold known as a ruga.

Function: Storing and breaking down the food and liquids that are consumed during meals is the stomach’s primary function. In order to aid in the digestion of food and other foreign materials like bacteria, it creates hydrochloric acid and enzymes. Such unwanted microbes are killed by the stomach’s acidic environment. Additionally, it aids in digestion by contracting its muscles at regular intervals to churn the food swallowed.

[4] Caecum c.s.

Structure: The caecum, a sac-like structure hanging inferior to the ileocecal valve, is the first portion of the large intestine. It takes in the contents of the ileum and continues to absorb salts and water. It is roughly 6 cm (2.4 in) in length.

Function: The two primary purposes of the caecum are the microbial digestion of soluble and insoluble carbohydrates prior to their entry to the ascending colon and the absorption of substantial amounts of water and electrolytes.

[5] Frog Small Intestine c.s.

Structure: The small intestine of a frog can be found in numerous loops supported by the mesentery, which is a membrane that resembles a fan. The duodenum is the portion of the small intestine that curves upward to create a U with the stomach, and the coiled ileum makes up the remaining portion of it. The pancreas and liver provide the pancreatic and bile juice to the duodenum through an opening known as the common hepatopancreatic duct. And the low transverse folds in the small intestine contain the inner mucous lining, which contains the goblet and absorbing cells.

Function: The small intestine’s primary roles include breaking down food, absorbing nutrients the body needs, and eliminating waste.

[6] Gallbladder Human c.s.

Structure: The gallbladder is a little, pear-shaped organ that sits deep under your liver in your abdomen. The fundus, body, and neck are the three separate components that make up this organ. The circular base that faces the abdominal wall is formed by the fundus. While the neck tapers into the cystic duct to form a portion of the biliary tree, and the body lies in an indentation in the lower liver.

Function: The function of this organ is to hold bile until digestion calls for it. The gallbladder squeezes or contracts in response to food, allowing bile to enter your digestive system. It can store 1 and 2.7 fluid ounces of bile on average. The gallbladder constricts after a fatty meal to release the bile it has been holding into the small intestine.

[7] Human Appendix c.s.

Structure: The human body’s muscular appendix, also known as the vermiform appendix, is joined to the large intestine. It is called after the Latin word “vermiform,” which means “worm-shaped,” and is a thin tube that resembles a worm. The caecum, a pouch-like structure in the large intestine, is where the appendix originates. It typically has a diameter of 7 to 8 mm and a length of 2 to 20 cm, with an average length of 9 cm. Normally, the appendix is found on the lower right side of the abdomen. This organ, often referred to as the cecal appendix or vermix, is composed of an inner mucosa layer that is just the same with the rest of the digestive tract.

Function: It is still unclear exactly what the vermiform appendix’s role in the human body is. Scientists think it’s a vestigial remnant, meaning that although it had a necessary purpose in human digestion in the past, as we’ve progressed, it has become insignificant. However, the appendix may play a part in the body’s immune processes because, according to certain research findings, it is full of lymphoid cells, which aid in the body’s defense against infections, thereby considering it as a secondary lymphoid organ.

[8] Human Spleen sect.

Structure: The spleen is a large bean-shaped organ located beneath the diaphragm on the left side of the body. It is encapsulated, and is a key organ of the mononuclear phagocyte system and contains many phagocytes, T and B lymphocytes, and other immune cells. Over the course of a person’s lifetime, the spleen can vary in size and weight, but in an adult, it typically measures 12 cm in length, 8 cm in width, 3–4 cm in thickness, and weighs 200 grams. Its diaphragmatic surface is in contact with the diaphragm’s inner surface, and it possesses also the visceral surface. Additionally, the spleen has a peritoneum exterior layer that forms trabeculae and is firmly adhered to the splenic capsule, an interior fibro-elastic coat that dips within the organ.

Function: The main function of the spleen is to filter your blood. It identifies and eliminates red blood cells that are damaged, aging, or malformed. It is responsible for “quality control” as blood flows into it; red blood cells have to squeeze through a complex network of tiny openings. All of your blood’s healthy cells just continue to flow throughout your system after passing through the spleen. Macrophages in this organ will break down any blood cells that fail the test.

[9] Tonsil Human sect.

Structure: The two oval-shaped tissues called tonsils are located on either side of the throat, near the very back of the mouth. When someone describes their tonsils, they typically refer to these, which are known as palatine tonsils. But we also have three other types of tonsils: a pair of tubal tonsils at the bottom of the auditory canal, a pair of lingua tonsils at the base of the tongue, and the adenoid or pharyngeal tonsil at the back of the nasal cavity. Waldeyer’s tonsillar ring is made up of all of these tonsils combined.

Function: Despite its diminutive size, tonsils are crucial to the upkeep of our immunity. Similar to how goalies in a soccer match works, they also help in stopping foreign objects from entering the lungs. Microorganisms including bacteria and viruses can be filtered by tonsils. The immune cells found in this organ create antibodies that aid in destroying germs and preventing lung and throat infections.

[10] Human Tongue Posterior c.s.

Structure: The floor of the mouth is occupied by the tongue, which is made of striated muscle. Taste buds and papillae abound on the stratified squamous epithelium that makes up the dorsal mucosal surface. The tongue is also a voluntary muscle structure that is attached to the floor of the mouth by a fold known as the frenulum.

Function: The food is actively moved by the tongue around the mouth so that the teeth may break it down even further. In the mouth area, food is combined with saliva to form a bolus, which is a portion that can be transported into the pharynx, swallowed, and then passed down the esophagus and into the stomach. Additionally, by preventing food from coming into prolonged contact with the teeth, the tongue may aid with dental hygiene. The tongue also uses the taste buds’ sense of taste to determine what would be safe and appetizing to ingest.

References:

Healthdirect. (n.d.). Digestive system. https://www.healthdirect.gov.au/digestive-system

Lumen Learning. (n.d.). The Small and Large Intestines. https://courses.lumenlearning.com/suny-ap2/chapter/the-small-and-large-intestines/

Collins, J. T., Nguyen, A., & Badireddy, M. (2023). Anatomy, Abdomen and Pelvis, Small Intestine. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459366/

Lumen Learning. (n.d.). The Stomach. https://courses.lumenlearning.com/suny-ap2/chapter/the-stomach/

BYJU’S. (n.d.). Digestive System of Frog. https://byjus.com/neet/digestive-system-of-frog/

Cagle, P. (2024). Gallbladder function: What it does and why it matters. https://ezra.com/blog/gallbladder-function

Cheriyedath, S. (n.d.). What is the Appendix? https://www.news-medical.net/health/What-is-the-Appendix.aspx

Aryal, S. (2022). Spleen: Definition, Structure and Functions. https://microbenotes.com/spleen-structure-and-functions/

Hickok, K. (2022). Tonsils: Definition, anatomy and functions. https://www.livescience.com/62447-tonsils.html

du Toit D. F. (2003). The tongue: structure and function relevant to disease and oral health. SADJ : journal of the South African Dental Association = tydskrif van die Suid-Afrikaanse Tandheelkundige Vereniging, 58(9), 375–383. https://pubmed.ncbi.nlm.nih.gov/14964052/#:~:text=The%20 tongue%20 consists%20of%20 striated,the%20floor%20of%20the%20mouth