Chapter 21 - Blood Vessels and Circulation

Question 1

1. List the five general classes of blood vessels.

Answer 1

The five general classes of blood vessels are arteries, arterioles, capillaries, venules and veins.

Question 2

2. Which type of vessel is characterized by thin walls with very little smooth muscle tissue in the tunica media?

Answer 2

The blood vessels are veins. Arteries and arterioles have a large amount of smooth muscle tissue in a thick, well-developed tunica media.

Question 3

3. Why are valves located in veins but not in arteries?

Answer 3

In the arterial system, pressures are high enough to keep the blood moving forward. In the venous system, blood pressure is too low to keep the blood moving toward the heart. Valves in veins prevent blood from flowing backward whenever the venous pressure drops.

Question 4

4. Where in the body would you find fenestrated capillaries?

Answer 4

Fenestrated capillaries are located where fluids and small solutes move freely into and out of the blood, including endocrine glands, the choroid plexus of the brain, absorptive areas of the intestine, and filtration areas of the kidneys.