Question

The exchange of gases in the alveoli of the lungs takes place during respiration. Identify the labeling a-e.

• A. a-Air flows into and out of alveoli
  b-Deoxygenated blood
  c-Oxygenated blood
  d-Oxygen diffuses into red blood cells
  e-Carbon dioxide diffuses out of the plasma
• B. a-Air flows out of alveoli
  b-Oxygenated blood
  c-Deoxygenated blood
  d-Oxygen diffuses into red blood cells
  e-Carbon dioxide diffuses out of the plasma
• C. a-Air flows into alveoli
  b-Deoxygenated blood
  c-Oxygenated blood
  d-Carbon dioxide diffuses out of the plasma
  e-Oxygen diffuses into red blood cells
• D. a-Oxygen flows into and out of alveoli
  b-Oxygenated blood
  c-Deoxygenated blood
  d-Carbon dioxide diffuses out of the plasma
  e-Oxygen diffuses into red blood cells

Answer 1

Answer: (A)

Gaseous exchange between blood (dissolved phase) and alveolar air (gaseous phase) across respiratory membrane occurs by simple diffusion. Obviously, it depends upon the concentration gradient (partial pressure) of the concerned gases in blood and alveolar air.