Whether sleeping or exercising,the rate of gas exchange is precisely matched to the body's immediate respiratory needs;gas exchange during exercise,for example,increases because
A) when muscle contracts,the adjacent capillaries are compressed,forcing the gases out and into the surrounding tissues.
B) active cells are warmer than resting cells.
C) the rate of diffusion is proportional to the gas concentration gradients that are high during exercise and low during rest.
D) the elevated blood pressures during activity expands the capillaries,which increases the surface area available for gas exchange.

Question

Quizplus · Accepted Answer

During exercise, there is an increased demand for oxygen and an increased production of carbon dioxide by the active cells. This results in a higher concentration gradient between the alveoli and the blood, which leads to an increase in the rate of diffusion and gas exchange. The rate of diffusion is directly proportional to the concentration gradient between the two regions. Therefore, choice C is the best answer. Choices A, B, and D are incorrect because they do not accurately explain the mechanism behind the increase in gas exchange during exercise.

Whether Sleeping or Exercising,the Rate of Gas Exchange Is Precisely