Most of the carbon dioxide carried in the blood travels as
Correct answer: A. hydrogen carbonate ions dissolved in the plasma
- A. hydrogen carbonate ions dissolved in the plasma
- B. carbaminohaemoglobin
- C. carbon dioxide dissolved in the plasma
- D. carbon monoxide
Explanation
About seventy per cent of carbon dioxide enters the red cells, where carbonic anhydrase converts it with water into carbonic acid, which dissociates into hydrogen and hydrogen carbonate ions, and the latter diffuse out into the plasma. Roughly twenty three per cent is carried on haemoglobin as carbaminohaemoglobin and only about seven per cent stays simply dissolved. The reactions reverse in the lungs.
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About Gaseous Exchange in Lungs
Gaseous exchange in the lungs occurs across the thin, moist alveolar and capillary surfaces, where oxygen and carbon dioxide diffuse down partial pressure gradients. The topic covers alveolar adaptations, ventilation, the role of haemoglobin in oxygen transport, carbon dioxide carriage, and the difference between external gas exchange and cellular respiration.
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