19. The Blood Vessels

Arteries tend to have thicker walls than veins. Which of the following is a reason for this?

The pressure at point A in the circulatory system is 15 mm Hg, & the pressure at point B is 8 mm Hg. Blood is flowing from point A to point B, then a physiological change causes the pressure at point B to increase to 10 mm Hg. What will happen to the rate of blood flow?

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?

Vern is suffering from cardiac arrhythmias and is brought into the emergency room of a hospital. In the emergency room he begins to exhibit tachycardia and as a result loses consciousness. Explain why Vern lost consciousness.

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 would not result in the dilation of the terminal arterioles and upstream arterioles in systemic capillary beds?

a. A decrease in local tissue O₂ content

b. An increase in local tissue CO₂

c. A local increase in histamine

d. A local increase in pH

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

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