During gaseous exchange in the lungs, carbon dioxide moves

  • A. from the alveolar air into the blood
  • B. from red blood cells into haemoglobin
  • C. from the blood into the alveolar air
  • D. from the plasma into the lymph

Explanation

Venous blood arrives with a higher CO2 pressure than alveolar air, so the gas diffuses out to be exhaled. The opposite direction would defeat the entire purpose of ventilation.

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