5 topics with brief reviews: definitions, key facts, and class questions.
This section focuses on the microscopic structure of the respiratory system. Here, we systematically examine the histology of the air-conducting passages—from the nasal cavity and larynx through the trachea and bronchial tree directly to the respiratory division of the lung, where gas exchange actually takes place.
During practical classes and colloquia, you are guaranteed to be asked about the cellular composition of the pseudostratified ciliated epithelium, the principles of structural changes in the bronchial wall as their caliber decreases, and the components of the air-blood barrier.
The material is structured from general to specific. Start with the basic characteristics of the system to grasp the logic of its structure, and then proceed to the detailed histology of each division. This knowledge is not just an academic baseline, but the foundation for understanding the pathogenesis of bronchial asthma, COPD, and pneumonia in your future clinical practice.
Where do the air-conducting passages end and gas exchange begin?
The air-conducting passages end at the terminal bronchioles (about 0.5 mm in diameter). Respiratory bronchioles begin immediately beyond them, with alveoli appearing in their walls—this is where gas exchange starts.
Is there a submucosa in the nasal cavity?
No, the submucosa is absent. The mucosa is tightly fused with the perichondrium or periosteum, forming a mucoperiosteum.
Why are the vestibular folds of the larynx called "false"?
Skeletal muscle tissue is absent within their thickness. Because of this, they do not participate in altering the lumen of the rima glottidis and play no role in phonation.
Why does the lumen of a small bronchus appear star-shaped on a histological slide?
This is the result of the contraction of a robust muscular layer. Due to the complete absence of a stabilizing cartilaginous framework, the mucosa of a small bronchus easily gathers into deep folds.
What mechanism prevents alveoli from collapsing during expiration?
Surfactant prevents collapse. The specific phospholipid in its composition remains solid at body temperature and is retained in the surface layer during expiration, preventing the walls from sticking together.
Master the entire topic in the "Histology" course
This is a summary. The course covers everything tested in classes and exams.
3,485 pages of study guides for all topics
Assignments and quizzes after every topic — just like in a colloquium