Question

Which of the following is true about veins?

a) Veins have a small lumen in relation to the thickness of the vessel wall.
b) Venous valves are formed from the tunica media.
c) Up to 35% of total body blood is in venous circulation at any given time.
d) Veins are called capacitance vessels or blood reservoirs.

Answer 1

Veins are incorrectly described as having small lumens about their vessel walls; they have large lumens. Venous valves are not formed from the tunica media. It is also incorrect that only 35% of body blood is in the veins at one time; the correct figure is 64%. True statement: Veins are called capacitance vessels or blood reservoirs. The correct option is c.

Step-by-step explanation:

The question pertains to the characteristics of veins in the circulatory system. Based on the information provided:

• Option a) is incorrect because veins, in contrast to arteries, have a large lumen concerning the thickness of the vessel wall.
• Option b) is incorrect as venous valves are not formed from the tunica media; instead, they are extensions of the tunica intima.
• Option c) is also incorrect because up to 64% of total body blood is in venous circulation at any given time, not 35%.
• Option d) is correct as veins are indeed called capacitance vessels or blood reservoirs due to their ability to hold a large volume of blood at low pressure.

Therefore, the true statement about veins is that they are called capacitance vessels or blood reservoirs.