When the diaphragm and external intercostal muscles contract,

(a) Exhalation occurs.

(b) Intrapulmonary pressure increases.

(c) Intrapleural pressure decreases.

(d) The volume of the lungs decreases.

(e) The size of the thoracic cavity increases.

What three integrated steps are involved in external respiration?

Which of the following does not occur in internal respiration?

(a) Oxygen diffuses from the blood to the interstitial spaces.

(b) Carbon dioxide diffuses from the interstitial spaces to the blood.

(c) Hemoglobin binds more oxygen.

(d) Bicarbonate ions are formed in red blood cells.

(e) Chloride ions diffuse into red blood cells as bicarbonate ions diffuse out.

Gas exchange at the blood air barrier is efficient because

(a) The differences in partial pressure are substantial

(b) The gases are lipid soluble

(c) The total surface area is large

(d) Of all of these