The structure of a capillary wall differs from that of a vein or an artery becausea. it has two tunics instead of three,b. there is less smooth muscle,c. it has a single tunic—only the tunica intima,d. none of these.

Which of the following statements is true?

Which blood vessel layer contains the greatest proportion of collagen?

Which blood vessel tunic has the most active role in controlling blood flow?

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

b. The tunica intima is composed of a sheet of endothelium, connective tissue, and the internal elastic lamina.

Collagen vascular diseases weaken the collagen in the tunica externa of blood vessels. Predict the effects of such a disease.