1. Lungs. The lungs are paired organs flanking the mediastinum in the thoracic cavity. Each lung is covered with pulmonary (visceral) pleura; the thorax wall is lined with parietal pleura. Pleural fluid decreases friction during breathing. The lungs are primarily elastic tissue and passageways of the bronchial tree. The smallest passageways end in clusters of air sacs called alveoli
Bronchial Tree. After entering the lungs, the main bronchi subdivide into smaller and smaller branches (secondary and tertiary bronchi, and so on), finally ending in the smallest of the conducting passageways, the bronchioles. Because of this branching and rebranching of the respiratory passageways within the lungs, the network formed is often referred to as the bronchial, or respiratory tree.
Alveoli. The terminal bronchioles lead into respiratory zone structures, even smaller conduits that eventually terminate in alveoli, or air sacs. The respiratory zone, which includes the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, is the only site of gas exchange
2. Trachea. This is also commonly called the windpipe, is the main airway to the lungs. It divides into the right and left bronchi at the level of the fifth thoracic vertebra, channeling air to the right or left lung. A hyaline cartilage in the tracheal wall provides support and keeps the trachea from collapsing. The posterior soft tissue allows for expansion of the esophagus, which is immediately posterior to the trachea.
3. Respiratory Epithelium. There are four main histological layers within the respiratory system: respiratory mucosa, which includes epithelium and supporting lamina propria, submucosa, cartilage and/or muscular layer, and adventitia. Respiratory epithelium is ciliated pseudostratified columnar epithelium found lining most of the respiratory tract; it is not present in the larynx or pharynx.
The epithelium classifies as pseudostratified; though it is a single layer of cells along the basement membrane, the alignment of the nuclei is not in the same plane and appears as multiple layers. The role of this unique type of epithelium is to function as a barrier to pathogens and foreign particles; however, it also operates by preventing infection and tissue injury via the use of the mucociliary elevator.
FUN FACTS:
1. The left lung tends to be smaller than the right lung in people to accommodate for the heart, which is located on the left side of the body.
2. Lungs can float on water. They are the only body organs that can float, largely related to the air that is contained within alveoli.
3. If the lungs were unfolded and expanded out to their fullest size, they’d be roughly the size of a tennis court.
4. The lung capacity of an adult is approximately 4 to 6 liters of air. Males tend to have larger lung capacity than females. We only breathe in about 0.5 liters with each breath.
5. A portion of the air you breathe never reaches the alveoli. It is referred to as dead air because it isn’t used in gas exchange.
1. Lungs. The lungs are paired organs flanking the mediastinum in the thoracic cavity. Each lung is covered with pulmonary (visceral) pleura; the thorax wall is lined with parietal pleura. Pleural fluid decreases friction during breathing. The lungs are primarily elastic tissue and passageways of the bronchial tree. The smallest passageways end in clusters of air sacs called alveoli
Bronchial Tree. After entering the lungs, the main bronchi subdivide into smaller and smaller branches (secondary and tertiary bronchi, and so on), finally ending in the smallest of the conducting passageways, the bronchioles. Because of this branching and rebranching of the respiratory passageways within the lungs, the network formed is often referred to as the bronchial, or respiratory tree.
Alveoli. The terminal bronchioles lead into respiratory zone structures, even smaller conduits that eventually terminate in alveoli, or air sacs. The respiratory zone, which includes the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, is the only site of gas exchange
2. Trachea. This is also commonly called the windpipe, is the main airway to the lungs. It divides into the right and left bronchi at the level of the fifth thoracic vertebra, channeling air to the right or left lung. A hyaline cartilage in the tracheal wall provides support and keeps the trachea from collapsing. The posterior soft tissue allows for expansion of the esophagus, which is immediately posterior to the trachea.
3. Respiratory Epithelium. There are four main histological layers within the respiratory system: respiratory mucosa, which includes epithelium and supporting lamina propria, submucosa, cartilage and/or muscular layer, and adventitia. Respiratory epithelium is ciliated pseudostratified columnar epithelium found lining most of the respiratory tract; it is not present in the larynx or pharynx.
The epithelium classifies as pseudostratified; though it is a single layer of cells along the basement membrane, the alignment of the nuclei is not in the same plane and appears as multiple layers. The role of this unique type of epithelium is to function as a barrier to pathogens and foreign particles; however, it also operates by preventing infection and tissue injury via the use of the mucociliary elevator.
FUN FACTS:
1. The left lung tends to be smaller than the right lung in people to accommodate for the heart, which is located on the left side of the body.
2. Lungs can float on water. They are the only body organs that can float, largely related to the air that is contained within alveoli.
3. If the lungs were unfolded and expanded out to their fullest size, they’d be roughly the size of a tennis court.
4. The lung capacity of an adult is approximately 4 to 6 liters of air. Males tend to have larger lung capacity than females. We only breathe in about 0.5 liters with each breath.
5. A portion of the air you breathe never reaches the alveoli. It is referred to as dead air because it isn’t used in gas exchange.
SOURCES:
https://training.seer.cancer.gov/anatomy/respiratory/
https://training.seer.cancer.gov/anatomy/respiratory/passages/larynx.html
https://biologydictionary.net/respiratory-system-fun-facts/
Marieb, E. N., & Keller, S. M. (2018). The Respiratory System. In E. N. Marieb, & S. M. Keller, Essentials of Human Anatomy & Physiology (12th Edition) (pp. 469-470). New York City: Elsevier.
Kia’i N, Bajaj T. Histology, Respiratory Epithelium. [Updated 2021 May 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541061/