Wk.11 L2 - Questions

Question 1

What are the main functions of the respiratory system as outlined in this lecture?

Answer 1

Air conduction, conditioning & filtration; gas exchange; speech production; sense of smell; and regulation of immune responses.

Question 2

Describe the histological features of the olfactory mucosa.

Answer 2

It is composed of a pseudostratified columnar epithelium with four cell types (olfactory receptor, sustentacular, basal, and brush cells) overlying a lamina propria with nerves, vessels, and sero-mucous glands.

Question 3

List the four cell types found in the olfactory epithelium.

Answer 3

Olfactory receptor cells, sustentacular cells, basal cells, and brush cells.

Question 4

Why is the olfactory epithelium described as pseudostratified?

Answer 4

Because all cells contact the basement membrane, though their nuclei are at different heights.

Question 5

Which olfactory cells are responsible for detecting odorants, and what is a key feature of these cells?

Answer 5

Olfactory receptor cells; they have ~20 long cilia per cell and a single dendrite that extends into the lumen.

Question 6

What is the role of sustentacular cells in the olfactory mucosa?

Answer 6

They provide metabolic support and secrete odorant-binding proteins to aid olfaction.

Question 7

What function do basal cells serve in the olfactory epithelium?

Answer 7

They act as stem cells, differentiating into the other cell types.

Question 8

Describe the function of brush cells in the olfactory area.

Answer 8

They are thought to have a sensory role and form synaptic connections with trigeminal nerve axons.

Question 9

What is the typical histological appearance of the respiratory epithelium?

Answer 9

Ciliated pseudostratified columnar epithelium containing ciliated cells, goblet cells, brush cells, and basal cells.

Question 10

List the four cell types present in the respiratory epithelium.

Answer 10

Ciliated cells, goblet cells, brush cells, and basal cells.

Question 11

What is the primary function of ciliated cells in the respiratory epithelium?

Answer 11

To propel mucus and trapped particles out of the airways via coordinated ciliary beating.

Question 12

What role do goblet cells play in the respiratory tract?

Answer 12

They secrete mucus to trap particulate matter and pathogens.

Question 13

How do brush cells differ from the other epithelial cells in the respiratory tract?

Answer 13

They possess microvilli instead of cilia and may be involved in chemosensation.

Question 14

What is the importance of basal cells in the respiratory epithelium?

Answer 14

They serve as progenitor cells to repair and regenerate the epithelium.

Question 15

Describe the layered structure of the tracheal wall.

Answer 15

It consists of an inner ciliated pseudostratified columnar epithelium with a thick basement membrane, a lamina propria, submucosa with glands and smooth muscle (trachealis), C-shaped rings of hyaline cartilage, and an outer adventitia.

Question 16

What distinguishes the trachea from smaller airways histologically?

Answer 16

The trachea has C-shaped hyaline cartilage rings and submucosal glands, features not present in smaller airways.

Question 17

How does airway wall structure change as the lumen diameter decreases?

Answer 17

Epithelial height and overall wall thickness decrease in smaller airways.

Question 18

Describe the histological features of a bronchus.

Answer 18

A bronchus has a mucosa lined by ciliated pseudostratified columnar epithelium, a loose connective tissue lamina propria, submucosa with smooth muscle, hyaline cartilage plates, and an adventitia.

Question 19

How do bronchioles differ from bronchi in their structure?

Answer 19

Bronchioles lack cartilage and submucosal glands; they have a thinner, columnar to cuboidal epithelium and a continuous smooth muscle layer.

Question 20

What are the key features of the terminal bronchiole?

Answer 20

It is lined by simple cuboidal epithelium with Clara cells, has minimal smooth muscle, and no goblet cells.

Question 21

How is a respiratory bronchiole histologically distinct?

Answer 21

It is lined by simple squamous epithelium in areas where alveoli are present, with occasional Clara cells and minimal smooth muscle.

Question 22

Approximately how many alveoli are found in an adult lung?

Answer 22

About 200 million alveoli.

Question 23

Name the two main types of alveolar cells and their functions.

Answer 23

Type I alveolar cells: thin, squamous cells for gas exchange; Type II alveolar cells: cuboidal cells that secrete surfactant and can differentiate into Type I cells.

Question 24

What is the role of surfactant in the alveoli?

Answer 24

It reduces surface tension to prevent alveolar collapse and facilitates gas exchange.

Question 25

What is the function of alveolar macrophages?

Answer 25

They phagocytose particulates and pathogens, aiding in pulmonary immune defense.

Question 26

Describe the structure of the blood-air barrier.

Answer 26

It consists of the alveolar Type I cell, its fused basal lamina, and the capillary endothelial cell, allowing efficient gas exchange.

Question 27

What histological feature of the alveoli facilitates efficient diffusion of gases?

Answer 27

The thin, simple squamous epithelium of Type I cells.

Question 28

How does the lamina propria differ in the olfactory mucosa compared to the respiratory tract?

Answer 28

In the olfactory mucosa it contains olfactory nerves and sero-mucous glands, while in the respiratory tract it is mainly loose connective tissue with vessels and immune cells.

Question 29

How does the mucociliary mechanism work in the respiratory epithelium?

Answer 29

Goblet cells secrete mucus to trap particles and ciliated cells sweep the mucus upward toward the pharynx for clearance.

Question 30

What role does the respiratory tract’s lamina propria play in immunity?

Answer 30

Its high vascularity and cellularity (lymphocytes, mast cells, etc.) support immune surveillance and tissue repair.

Question 31

What is the function of Clara cells in the bronchioles?

Answer 31

They secrete a surface-active protein that prevents airway collapse and serve as stem cells for epithelial repair.

Question 32

Why is a thick basement membrane important in respiratory histology?

Answer 32

It provides structural support and maintains epithelial integrity during breathing and coughing.

Question 33

What distinguishes the alveolar ducts from the alveoli?

Answer 33

Alveolar ducts are larger passageways that contain clusters of alveoli, which are the primary sites of gas exchange.

Question 34

Outline the cellular components of the blood-air barrier.

Answer 34

Alveolar Type I cell, fused basal lamina, and the capillary endothelial cell.

Question 35

Explain how the structure of the respiratory epithelium supports air filtration.

Answer 35

Mucus from goblet cells traps debris, while cilia beat rhythmically to clear the mucus, ensuring clean air enters the lungs.

Question 36

How do anatomical changes in the airway (epithelial height, wall thickness) correlate with airway function?

Answer 36

Smaller airways have thinner walls to maximize gas exchange, while larger airways have robust structures for air conduction and filtration.

Question 37

What is the significance of the respiratory epithelium's ciliated pseudostratified organization?

Answer 37

It combines effective mucus clearance with a regenerative capacity provided by basal cells.

Question 38

How do the histological structures of the olfactory and respiratory regions differ?

Answer 38

The olfactory region has specialized receptors and supporting cells for smell, whereas the respiratory region is primarily adapted for efficient air conduction and gas exchange.

Question 39

What roles do the connective tissue layers play in the respiratory passages?

Answer 39

They provide structural support, house blood vessels and nerves, and contribute to immune defense.

Question 40

Summarize the functional significance of the blood-air barrier.

Answer 40

It minimizes diffusion distance for gases, ensuring rapid and efficient oxygen and carbon dioxide exchange between air and blood.