49 Questions
Which component of the respiratory system is responsible for filtering, moistening, and warming the inspired air before it reaches the lungs?
Nasal cavity
Which of the following is NOT part of the conducting portion of the respiratory system?
Alveolar ducts
What is the function of the sphenoidal sinus in the respiratory system?
Conveying air from the external environment to the lungs
Which part of the respiratory system consists of respiratory bronchioles, alveolar ducts, and alveoli?
Lungs
In which layer of the trachea is the mucosa found?
Epithelium
What is the main function of the lower respiratory tract?
Gas exchange between air and blood
What is the function of type I alveolar cells?
Maintain the alveolar side of the blood-air barrier
What is the main role of type II alveolar cells?
Secrete pulmonary surfactant to lower alveolar surface tension
What is the function of alveolar macrophages?
Phagocytose debris and erythrocytes
What happens to type II cells after injury?
They divide to replace their own population and provide progenitor cells for type I cells
What stimulates Clara cells to divide and give rise to alveolar cells?
Inhalation of toxic gases or similar materials
What is the function of the pleural cavity?
To produce a thin film of serous fluid that acts as a lubricant
In which part of the trachea can seromucous glands be found?
Submucosa
What type of cells are most numerous in the cuboidal epithelium of terminal bronchioles?
Clara cells
What is the function of the smooth muscle in the bronchi and bronchioles?
To control muscular contraction primarily by nerves of the autonomic nervous system
What structures line the alveolar ducts?
Ciliated cuboidal epithelium
Which component of the trachea contains hyaline cartilage rings?
Adventitia
What can be found in the lamina propria of the bronchi?
Crisscrossing bundles of spirally arranged smooth muscle and elastic fibers
What is the main function of clara cells in the terminal bronchioles?
Secretion of surfactant lipoproteins and mucins in the fluid layer on the epithelial surface
What is the distinguishing feature of bronchioles in terms of their structure?
Absence of mucosal glands and cartilage
What cell types can be found in the terminal bronchiole epithelium?
Clara cells, ciliated cells, small mucous cells, brush cells, DNES small granule cells
What type of tissue surrounds each alveolar duct and its alveoli?
Elastic and collagen fibers
What structures disappear at the distal end of alveolar ducts?
Smooth muscle
What is the main function of clara cells in injury-induced situations?
Injury-induced mitosis for replacement of other bronchiolar cell types
What is the main function of the trachealis muscle in the trachea?
To regulate the diameter of the trachea
Which cell type is most numerous in the epithelium of terminal bronchioles?
Clara cells
What is the distinguishing feature of bronchioles in terms of their structure?
No cartilage in their walls
In which part of the respiratory system can clara cells be found?
Terminal bronchioles
What is the main function of alveolar macrophages in the lungs?
Phagocytosis of foreign particles and pathogens
Which of the following is NOT part of the conducting portion of the respiratory system?
Respiratory bronchioles
What is the distinguishing feature of bronchioles in terms of their structure?
Lack of cartilage rings
What is the main function of clara cells in injury-induced situations?
Detoxification of harmful substances
What is the function of alveolar macrophages?
Phagocytosis of foreign particles
What type of tissue surrounds each alveolar duct and its alveoli?
Elastic connective tissue
Which cells in the alveoli lower the alveolar surface tension?
Type II alveolar cells
What is the primary function of type I alveolar cells?
Maintaining the blood-air barrier
What is the function of alveolar macrophages?
Phagocytosing debris and erythrocytes
What stimulates Clara cells to divide and give rise to alveolar cells?
Inhalation of toxic gases
Where are lamellar bodies containing pulmonary surfactant found?
Type II alveolar cells
What is the primary function of type II alveolar cells?
Secrete pulmonary surfactant to lower alveolar surface tension
What is the function of alveolar macrophages in the lungs?
Phagocytose debris and erythrocytes
Where are lamellar bodies containing pulmonary surfactant found?
Type II alveolar cells
What stimulates Clara cells to divide and give rise to alveolar cells?
Inhalation of toxic gases
What is the main function of the pleural cavity?
Produce a thin film of serous fluid as a lubricant
Type I alveolar cells reduce the thickness of the cytoplasm at the blood-air barrier to as little as 25 nm.
True
Type II alveolar cells secrete pulmonary surfactant which lowers the alveolar surface tension.
True
Alveolar macrophages are found in alveoli and in the interalveolar septum, often seen on the surface of the alveolus.
True
The pleural cavity is lined with mesothelial cells that normally produce a thin film of serous fluid acting as a lubricant.
True
Inhalation of toxic gases or similar materials can result in increased mitotic activity in the remaining type I alveolar cells.
True
Study Notes
Overview of the Respiratory System
- Consists of two main components: conducting portion and respiratory portion
- Conducting portion includes nasal cavities, nasopharynx, larynx, trachea, bronchi, and bronchioles
- Respiratory portion includes respiratory bronchioles, alveolar ducts, and alveoli
Trachea
- Has three layers: mucosa, submucosa, and adventitia
- Mucosa consists of respiratory epithelium, lamina propria, and seromucous glands
- Epithelium is pseudostratified ciliated columnar with goblet cells, brush cells, small granule cells, and basal cells
- Contains 16-20 C-shaped hyaline cartilage rings that keep the tracheal lumen open
Bronchi and Bronchioles
- Bronchi branch into primary, secondary, and tertiary bronchi
- Bronchioles branch off from tertiary bronchi and decrease in diameter
- Bronchi and bronchioles have similar structure to trachea, but with decreasing amounts of cartilage and glands
- Clara cells are present in terminal bronchioles, which secrete proteins to protect against pollutants and inflammation
Respiratory Bronchioles and Alveoli
- Respiratory bronchioles subdivide into alveolar ducts lined by alveoli
- Alveoli are sac-like structures with a thin layer of squamous alveolar cells and a network of elastic and reticular fibers
- Alveolar ducts open into atria, which communicate with alveolar sacs
- Alveoli have a total internal surface area of 75 m2 in each adult lung
Blood-Air Barrier
- Consists of surface lining and cytoplasm of alveolar cells, fused basal lamina, and cytoplasm of endothelial cells
- Total thickness of the barrier varies from 0.1 to 1.5 μm
- Capillary endothelial cells are thin and continuous, with numerous pinocytotic vesicles for efficient gas exchange
Test your knowledge of the lower respiratory tract with this quiz. Learn about the anatomy and functions of structures such as the larynx, trachea, bronchi, and lungs.
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