33 Questions
What is the main function of the respiratory system?
To exchange gases between the body and the environment
Which of the following is NOT part of the conductive airways in the respiratory system?
Alveoli
What are the three regions of the nasal cavity?
Nasal vestibule, respiratory region, olfactory region
What is the composition of the conductive airways?
Nasal cavity, bronchioles, alveolar ducts
What is the primary function of type I pneumocytes?
Diffusing respiratory gases
Where are Club cells mainly found in the respiratory system?
In the bronchioles
Which type of epithelium is predominantly found in the bronchioles?
Simple cuboidal epithelium
What is the primary function of type II pneumocytes?
Producing lung surfactant
Which cells primarily rest on type I pneumocytes and engulf particles of inspired air and toxins?
Pulmonary alveolar macrophages (PAMs)
Which component primarily decreases as cartilaginous sheets are formed in the respiratory system?
Smooth muscle fibers
Where is the mucosa lined by a pseudostratified ciliated columnar epithelium with Club or Clara cells and neuroendocrine cells?
Primary intrapulmonary bronchi
What is evident in pigs and forms bronchi associated lymphoid tissue (BALT) in the respiratory system?
Adventitia
Which structure is made up of respiratory bronchioles, alveolar ducts, alveolar sacs, and respiratory alveoli?
Pulmonary lobule
What is the composition of the interalveolar septum?
Highly vascularized thin connective tissue called the interstitium
What are the main components of submucosa in the respiratory system?
Tubuloacinar glands and smooth muscle fibers
Which part of the respiratory system has a muscularis mucosae of smooth muscle fibers?
Primary intrapulmonary bronchi
What is the function of the pulmonary intravascular macrophages (PIMs) in some species?
To remove toxins from the bloodstream that reach the lung
What is the function of the alveolar pores in the interalveolar septum?
To allow the passage of respiratory gases between alveoli
Which components make up the alveolar-capillary or haemato-air barrier?
Lung surfactant, type I pneumocyte cytoplasm, and septal capillary basement membrane
What is the most efficient point for oxygen exchange in the alveolocapillary barrier?
Basement membranes of the alveolus and the septal capillary fused
What is the composition of the pleura, a serous membrane in the avian respiratory system?
Loose connective tissue, mesothelium, and widely irrigated and innervated lining
What distinguishes the avian larynx from that of mammals?
Absence of vocal folds for sound production
In what way does the tracheal cartilage in birds differ from that in mammals?
Tracheal cartilage forms complete rings in birds
Where does vocalization occur in the avian respiratory system?
In the tracheobronchial junction where numerous membranes vibrate during sound production
What characterizes the lining of the mesobronchium in birds?
Simple non-ciliated cuboidal epithelium with goblet cells and spiral bands of smooth muscle in their lamina propria
What lines the air capillaries where gas exchange occurs in the avian lung?
Simple squamous epithelium similar to that of mammals
Which type of epithelium lines the rostral region of the nasal vestibule?
Pigmented keratinized squamous epithelium
What type of cells are found in the olfactory region of the nasal cavity?
Basal cells, olfactory neurosensitive cells, supportive cells
What type of cells are responsible for metabolizing toxic substances in the nasal cavity?
Club cells
What is the main function of serous glands in the lamina propria of the nasal cavity?
Produce lysozyme and enzymes to metabolize fat-soluble toxins
Which type of epithelium lines the respiratory region of the nasal cavity?
Pseudostratified ciliated columnar epithelium
What type of neurons form the olfactory nerve in the nasal cavity?
Bipolar neurons with a dendritic bulb
Which cell type is considered a sensory receptor in the olfactory region of the nasal cavity?
Brush cells
Study Notes
- The nasal vestibule is lined by different types of epithelium: pigmented keratinized squamous epithelium in rostral region, non-keratinized squamous epithelium in middle part, and pseudostratified non-ciliated columnar epithelium in caudal regions.
- The respiratory region of the nasal cavity is lined by a pseudostratified ciliated columnar epithelium. Five types of epithelial cells are identified: basal cells, ciliated epithelial cells, secretory cells (serous and mucous), brush cells, and non-ciliated cells.
- Basal cells are located at the base of the epithelium and can divide and differentiate into other epithelial cells. They have hemidesmosomes attached to the basement membrane.
- Ciliated epithelial cells are columnar cells with multiple cilia and microvilli. They have a nucleus in the basal portion and a supranuclear Golgi complex.
- Secretory cells produce and secrete specific substances. Serous cells contain neutral glycoproteins, while mucous cells synthesize and accumulate mucinogen. Brush cells have synapses with nerve cells and are considered sensory receptors. Non-ciliated cells metabolize toxic substances.
- The lamina propria is a loose vascularized connective tissue with serous glands. In the caudal regions, there is a cavernous stratum with numerous tortuous venous sinuses. Tubulo-acinar seromucous glands produce lysozyme and enzymes to metabolize fat-soluble toxins.
- The olfactory region is lined by a pigmented olfactory epithelium. It occupies the ethmoturbinates and the caudodorsal area of the nasal cavity and septum. Three cell populations exist: basal cells, olfactory neurosensitive cells, and supportive cells.
- Olfactory neurosensitive cells are bipolar neurons with a dendritic bulb containing cilia and vesicles. Axons cross the lamina propria as unmyelinated nerve fibers and form the olfactory nerve.
- Supportive cells are columnar cells with microvilli, a vesicular nucleus, and a well-developed Golgi complex. They have electron-dense pigment-containing granules.
- The olfactory mucosa is made up of loose connective tissue with numerous tubuloacinar seromucous glands (Bowman’s glands). The lamina propria eliminates odorous substances from the cilia of neurosensitive cells.
- The trachea is a tubular organ that connects the larynx and bronchi. It is made up of a mucosa, submucosa, hyaline cartilage, and muscularis (smooth muscle) or adventitia (depending on location).
- The mucosa is lined by a pseudostratified ciliated columnar epithelium, with added club cells and neuroendocrine cells. Club cells are secretory cells that metabolize toxic substances, while neuroendocrine cells are pyramidal-shaped cells that release hormones.
- The submucosa and the lamina propria are made up of vascularized connective tissue with many elastic fibers and abundant tubuloacinar seromucosal glands.
- The trachea has incomplete cartilages made up of hyaline cartilage. The shape is like the letter “U” or “C”, except in birds.
Test your knowledge of the anatomy and physiology of the respiratory system with this quiz. Explore topics such as the structure of the trachea, bronchial tree, and associated muscle fibers.
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