The largest fraction of carbon dioxide carried in systemic arterial blood is in the form of:
- A Bicarbonate ion in plasma and red cells ✓
- B Carbamino compounds bound to haemoglobin
- C Physically dissolved CO2 in plasma
- D Carbonic acid
Correct answer: A. Bicarbonate ion in plasma and red cells
Explanation
About 70 percent of transported CO2 travels as bicarbonate generated by carbonic anhydrase inside red cells, followed by the chloride shift. Carbamino-haemoglobin carries roughly 20 to 23 percent, and physically dissolved CO2 about 7 percent. The most tempting distractor is dissolved CO2: although CO2 is far more soluble than O2, its absolute dissolved fraction still remains small compared with bicarbonate.
Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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