The tunica media of a blood vessel is mostly __________ muscle.Group of answer choicescardiacfibrousskeletalsmooth

The tunica media of a blood vessel is mostly smooth muscle.

Explanation:

The blood vessel wall consists of three primary layers: the tunica intima (inner layer), tunica media (middle layer), and tunica externa (outer layer). The tunica media is crucial as it primarily comprises smooth muscle cells arranged in circular layers. This unique structure allows for the regulation of the blood vessel's diameter, facilitating the control of blood flow and pressure.

Smooth muscle is involuntary, meaning it functions without conscious control, providing the ability to maintain vascular tone and responding to various stimuli, such as hormonal signals. This is particularly important in vessels like arteries and arterioles, where changes in diameter (vasoconstriction and vasodilation) can directly influence systemic blood pressure and circulation.

In contrast, cardiac muscle is found in the heart, fibrous tissue offers structural support, and skeletal muscle is associated with voluntary movement. Thus, the correct choice specific to the tunica media of blood vessels is smooth muscle.