Question

Capacitance vessels have in their wall:

• A. More elastic tissue and less muscle
• B. Less elastic tissue and more muscle
• C. More elastic tissue and more muscle
• D. Less elastic tissue and less muscle

Hint:

Capacitance vessels are veins, which act as the body's low-pressure blood reservoir.

Answer 1

The Correct Option is D

Step 1: Capacitance vessels are the veins. They are called capacitance vessels because at any given moment they hold roughly 60 to 70 percent of the total blood volume and act as a reservoir.

Step 2: A vein wall has the same three tunicae as an artery (intima, media, adventitia), but the wall is much thinner. The tunica media in particular has only a small amount of smooth muscle, and the elastic tissue is scanty and is not organized into distinct internal and external elastic laminae.

Step 3: So compared with arteries, the venous wall has both less elastic tissue and less muscle, which makes the veins easily distensible and able to store large volumes at low pressure. This is exactly why they serve as capacitance vessels.

Step 4: The distractors describe arterial or arteriolar walls. Conducting arteries are elastin rich (more elastic tissue), while muscular arteries and arterioles are muscle rich (more muscle). Neither pattern fits a vein, so options a, b and c are wrong and the answer is option d.