Question

The blood leaving the lungs has all its haemoglobin oxygenated and gives up to the tissue because

• A. Tissue can absorb O${}_2$ from oxyhaemoglobin.
• B. O${}_2$ concentration is lower in tissue than in the lungs.
• C. Oxyhaemoglobin undergoes reduction.
• D. None of the above.

Answer 1

The correct option is B O${}_2$ concentration is lower in tissue than in the lungs.

OxygenO2 concentration is lower in the tissue than in the lungs. The partial pressure of oxygen at the arterial end is 100 mm/Hg and in the tissue, it is 40 mm/Hg. This creates a pressure gradient because of which oxygen transportation can occur. The partial pressure of oxygen is indicative of the mole fraction of oxygen present in the blood, hence gives the ideal picture of the oxygen concentration. Hence, the correct answer is option B.