When we are cold or the external temperature is low, most venous blood returning from the distal part of the arm travels in the deep veins where it picks up heat (by countercurrent exchange) from the nearby brachial artery en route. However, when we are hot, and especially during exercise, venous return from the distal arm travels in the superficial veins and those veins tend to bulge superficially in a person who is working out. Explain why venous return takes a different route in the second situation.

Which of the following physiological changes would likely occur in someone’s blood vessels when they begin an intense exercise session?

Assuming each of these blood vessels have the same difference in pressure along their length, which would have the lowest resistance and therefore, the greatest rate of blood flow?

Blood vessels primarily impact resistance to blood flow by:

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

e. The sympathetic nervous system causes vasodilation in the skin when body temperature decreases.