Let’s dedicate this week to RESPIRATORY PHYSIOLOGY

NEET PG Physiology
#1

Let’s dedicate this week to RESPIRATORY PHYSIOLOGY principles

• Diffusing capacity of the respiratory membrane:

  • CO is the diffusion-limited gas; it is used to measure the diffusing capacity (DLCO)
  • The diffusing capacity for oxygen (across the respiratory membrane) is ~ 21 mL/min/mm Hg. It means, if the pressure gradient (from alveolus to pulmonary capillary) is 1 mm Hg, then in 1 min, 21 mL of oxygen will diffuse through the respiratory membrane.
  • The alevolar-capillary pressure gradient is about 11 mm Hg. Hence, in 1 min., (21 X 11 = ) 230 mL of oxygen diffuses through the respiratory membrane. This is approximately the amount of oxygen consumed by the body (per min) under resting conditions.
  • The diffusing capacity may increase under certain conditions; for instance, exercise. This happens due to the opening up of the dormant capillaries, and a better V/Q match.