HMS, BM EQ-Bank 873 MC

A mountain climber ascends to 4,500 metres above sea level. Which of the following is an immediate physiological adaptation to the decrease in atmospheric oxygen pressure?

Decrease in heart rate
Increase in haemoglobin concentration
Increase in respiratory rate
Decrease in cardiac output

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\(C\)

Show Worked Solution

C is correct. An increase in respiratory rate is an immediate adaptation to compensate for reduced oxygen availability at high altitude.

Other Options:

A is incorrect: Heart rate typically increases, not decreases, at high altitude to deliver more oxygen.
B is incorrect: Increased haemoglobin concentration is a long-term adaptation to altitude, not immediate.
D is incorrect: Cardiac output typically increases, not decreases, at high altitude.