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Chapter 10. Respiratory System

What is the functional unit of the lung?

A. Alveolus

B. Bronchopulmonary segment

C. Intrapulmonary bronchus

D. Segmental bronchus

E. Terminal bronchiole

The answer is A: The alveolus is the functional unit of the lung because that is where gas exchange occurs.

A 25-year-old woman delivers a premature infant who develops severe respiratory difficulty. Arterial blood gases show severe hypoxemia. Which of the following cells is most likely too immature to function properly, resulting in these symptoms?

A. Alveolar macrophage

B. Basal cell

C. Goblet cell

D. Type I pneumocyte

E. Type II pneumocyte

The answer is E: Some of the final cells to mature and develop in a fetus are the type II pneumocytes, which are responsible for the production of surfactant. Without surfactant, the alveoli collapse after each breath, resulting in labored breathing by premature infants. Type I pneumocytes form the blood-air barrier.

A 60-year-old man makes an appointment with his family physician for a routine check-up. When the physician is taking his history, the man explains that he has smoked two packs of cigarettes a day for almost 45 years. A biopsy of an alveolar septum of his lung shows numerous cells containing black particles. Which of the following cell types most likely contains such particles?

A. Alveolar macrophages

B. Ciliated cuboidal cells

C. Endothelial cells

D. Goblet cells

E. Type I pneumocytes

F. Type II pneumocytes

The answer is A: Alveolar macrophages (dust cells) are often observed containing black granules of material picked up from the respiratory surfaces (such as dust, pollution, and material from cigarette smoke).

Asthma is a condition in which the mucosal lining of the airways becomes hypersensitive, often resulting in excessive bronchoconstriction of the smooth muscle in the airways. One treatment includes the use of muscarinic receptor antagonists, which cause bronchodilation by blocking the action of

A. Acetylcholine released from parasympathetic nerves

B. Acetylcholine released from sympathetic nerves


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