Muscle pump is

Which among the three layers of blood vessel wall—$Tunica \text{ intima}$, $Tunica \text{ media}$, and $Tunica \text{ externa}$—is comparatively thin in the veins?

What happens to the blood vessels after the death of a human?

Statement $X$: Blood is transported to the cells in the body through blood vessels.
Statement $Y$: Blood pressure is high and regular.

Which of the following are located in the $tunica \text{ } media$ of human blood vessels?

Arteries are best defined as the vessels which