[Campbell Biology P.935] Based on the Canada goose diagram and the accompanying descriptions... | Practice Question

Based on the Canada goose diagram and the accompanying descriptions points 1, 2, 3 , which statement accurately describes the temperature changes of blood in its leg during countercurrent heat exchange?

  • A: Arterial blood remains at 35°C throughout the leg, while venous blood warms from 9°C to 33°C.
  • B: As arterial blood cools from 35°C to 9°C towards the foot, venous blood warms from 9°C to 33°C as it returns to the body core.
  • C: Both arterial and venous blood experience a significant drop in temperature as they move away from the body core.
  • D: The primary heat transfer occurs when the venous blood temperature drops below the arterial blood temperature near the foot.

Explanation

The diagram clearly shows arterial blood entering the leg at 35°C and cooling to 9°C by the foot. Concurrently, venous blood returning from the foot starts at 9°C and warms to 33°C as it approaches the body core. This illustrates the efficient countercurrent heat exchange described in the text, where heat is transferred from the cooling arterial blood to the warming venous blood.