PRACTICE QUESTIONS

1. Which of the following lists includes only structures that compose the anatomic dead-space?

a. Respiratory bronchioles, alveoli, trachea, nasal cavity

b. Pharynx, bronchi, alveolar ducts, larynx

c.

d. Pharynx, nasal cavity, trachea, bronchi

e. Capillaries, respiratory bronchioles, alveolar ducts, alveoli

2. A horse has a tidal volume (VT) of 5 L, respiratory rate of 12 breaths/min, and VD/VT ratio of 0.5. Calculate minute ventilation (Ve) and alveolar ventilation (Va).

a. Ve = 60 L/min; Va = 2.5 LZmin

b. Ve = 30 L/min; Va = 30 L/min

c. Ve = 60 L/min; Va = 30 L/min

d. Ve = 2.5 L/min; Va = 1.25 L/min

e. Ve = 5.0 L/min; Va = 2.5 L/min

Which of the following occur during inhalation?

a. Diaphragm contracts, pleural pressure increases, alveolar pressure decreases.

b. Diaphragm relaxes, external intercostal muscles con­tract, pleural pressure increases.

c. Diaphragm relaxes, pleural pressure decreases, internal intercostal muscles relax.

d. External and internal intercostal muscles contract, pleural and alveolar pressures increase.

e. Diaphragm and external intercostal muscles contract, pleural and alveolar pressures decrease.

Lung compliance:

a. Has the units of pressure per volume (cm H₂O∕L).

b. Is greater at functional residual capacity (FRC) than at total lung capacity (TLC).

c. Is less when the lung is inflated with saline than when the lung is inflated with air.

d. Is greater in small mammals than in large mam­mals, even when adjusted for differences in lung size.

e. Is the only determinant of the change in pleural pressure during breathing.

5. Pulmonary surfactant:

a. Can be deficient in premature newborns.

b. Is produced in type II alveolar cells.

c. Is in part composed of dipalmitoyl phosphatidyl­choline.

d. Decreases surface tension of the fluid lining the alveoli.

e. All the above.

6. Which of the following increases the frictional resistance to breathing?

a. Intravenous administration of a β₂-adrenergic agonist

b. Contraction of the abductor muscles of the larynx

c. A decrease in lung volume from FRC to residual volume

d. Relaxation of the trachealis muscle

e. Inhibition of the release of histamine from mast cells

7. The distribution of ventilation within the lung is influenced by:

a. Regional variations in lung inflation

b. Regional variations in airway resistance

c. Regional variations in lung compliance

d. Collateral ventilation

e. All the above