18 Questions
What type of epithelium lines the false vocal cords?
Pseudostratified ciliated columnar epithelium with goblet cells
What is the main structural difference between the true and false vocal cords?
The true vocal cords have elastic fibers and a vocal ligament, while the false vocal cords do not
What is the function of the ventricles in the larynx?
They separate the false and true vocal cords
What is the primary function of the tracheal cartilage rings?
To keep the tracheal lumen open
Which layer of the tracheal wall contains the tracheal cartilage rings?
Submucosa
What is the approximate length and diameter of the adult trachea?
10-12 cm long and 2-2.5 cm in diameter
What is the main function of the tracheal glands located in the submucosa of the tracheal wall?
To produce mucus and lubricate the tracheal lumen
How do the cartilage rings in the tracheal wall differ from the cartilage plates in the bronchial wall?
The tracheal rings are circular, while the bronchial plates are flattened and interconnected
What is the primary difference in the epithelium lining the trachea versus the tertiary/segmental bronchi?
The tracheal epithelium has more goblet cells, while the bronchial epithelium has fewer goblet cells
What is the main structural difference between the primary/principal bronchi and the intrapulmonary bronchi (secondary and tertiary)?
The primary bronchi have cartilage rings, while the intrapulmonary bronchi have cartilage plates
What is the main structural difference between the tertiary/segmental bronchi and the bronchioles?
The tertiary bronchi have more cartilage, while the bronchioles completely lack cartilage
What is the primary function of the smooth muscle fibers that connect the free ends of the tracheal cartilage rings posteriorly?
To regulate the diameter of the tracheal lumen and facilitate airflow
What is the primary function of the conducting portion of the respiratory tract?
To warm and moisten the air
Which of the following is NOT a part of the respiratory portion of the respiratory tract?
Trachea
What type of epithelium lines the respiratory tract?
Pseudostratified columnar ciliated epithelium
What is the primary function of the goblet cells in the respiratory epithelium?
To produce mucus
Which of the following structures is NOT involved in gas exchange?
Larynx
What is the primary function of the lamina propria in the respiratory epithelium?
To provide structural support and vascularization
Study Notes
Respiratory Epithelium
- Consists of pseudostratified columnar ciliated epithelium with numerous goblet cells
- Supported by rich vascular lamina propria containing serous and mucous glands
- Function is to humidify and warm the inspired air, and trap small particles on the surface
Cells in Respiratory Epithelium
- Ciliated columnar cells
- Goblet cells
- Brush cells
- Basal cells
- Granule (Kulchitsky) cells
Larynx
- Has irregular lumen containing 2 pairs of vocal cords (upper and lower)
- Upper (false) cords are involved in voice production
- Lower (true) vocal cords are involved in voice production
- Ventricles are indentations that separate both cords on both sides of the larynx
- False cords: lined by pseudostratified ciliated columnar epithelium with goblet cells, lamina propria contains mixed sero-mucinous glands
- True cords: lined with non-keratinized stratified squamous epithelium, no glands are found in their lamina propria, elastic fibers, and the vocal ligament are attached to the tip of the cord
- Vocalis muscle is made of a bundle of skeletal muscle
Wall of Larynx
- Supported by three unpaired hyaline cartilages and three paired elastic cartilages
Trachea
- A wide, flexible tube 10-12 cm long and 2-2.5 cm in diameter
- Lumen is kept open by 16-20 tracheal C-shaped rings of hyaline cartilage
- Wall is formed of mucosa, submucosa, cartilage and muscle layer, and adventitia
- Mucosa consists of pseudostratified ciliated columnar epithelium with goblet cells (respiratory epithelium) and loose connective tissue rich in elastic fibers
- Submucosa is composed of loose connective tissue, tracheal glands (mixed serous and mucous glands), blood vessels, and ducts of glands
- Cartilage and muscle layer consists of tracheal rings (incomplete) made of hyaline cartilage, and posteriorly, the two free ends of rings are connected by smooth muscle (trachealis muscle) fibers
- Adventitia is formed of fibroelastic tissue
Bronchus
- Principal or extrapulmonary (primary) bronchus has same histology as trachea, except that cartilage rings become flattened interconnected plates, and the lamina propria is denser
- Intrapulmonary bronchi (2nd and 3rd order) have a wall composed of mucosa, muscle coat, submucosa, and adventitia
- Tertiary/segmental bronchus has a small diameter, columnar epithelium with less pseudostratification and less goblet cells, thin lamina propria, elastic and completely encircled with smooth muscle spirally arranged, and less seromucous glands in submucosa
Changes as Airways Become Smaller
- Cartilage becomes irregular and smaller, and is absent in bronchioles
Test your knowledge on the histology of the respiratory system with this quiz. Explore topics such as respiratory epithelium, types of cells in the respiratory system, histology of larynx, trachea, bronchial tree, alveoli, and the blood-air barrier. Presented by Dr. Snoor J. Mustafa for the 2023-2024 module.
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