19. The Blood Vessels

The local control of blood flow due to the action of precapillary sphincters is:

(a) Vasomotion

(b) Autoregulation

(c) Selective resistance

(d) Turbulence

How is the anatomy of capillaries and capillary beds well suited to their function?

Why do capillaries permit the diffusion of materials, whereas arteries and veins do not?

List three ways in which substances can cross the capillary wall.

Which of the following structures is the 'leakiest'?

a. Continuous capillary

b. Sinusoidal capillary

c. Precapillary sphincter

d. Fenestrated capillary

Which of the following correctly describes the flow of blood through a mesenteric capillary bed when the precapillary sphincters are constricted?

Blood flow in the capillaries is steady despite the rhythmic pumping of the heart because of the:

a. Elasticity of the large arteries

b. Small diameter of capillaries

c. Thin walls of the veins

d. Venous valves

Capillaries consist of:

a. Three thin tunics

b. Only a thin tunica intima with a well-developed internal elastic lamina

c. A thin sheet of endothelium with a basal lamina

d. Stratified epithelium