Long answer question:
Describe the histological structure of the artery, vein, and capillary.
The three structural layers of a generalized blood vessel from innermost to outermost are the tunica interna (intima), tunica media, and tunica externa. Modifications in this basic design account for the five types of blood vessels and the structural and functional differences among the various vessel types. In the transverse section of an artery, three layers can be seen. They are:
T. S. of Artery, Vein and Capillary-
1. Tunica externa or tunica adventitia:
It is a thick, tough layer of collagen fibers.
2. Tunica media:
It is the middle layer made up of smooth muscle fibers and a network of elastic fibers. This thick muscular and elastic layer makes the arterial wall pulsatile.
3. Tunica interna or intima:
The innermost tunica interna is a single layer of flat compact endothelial cells surrounding the lumen. The angular margin around the lumen shows tessellations. Arterial lumen is devoid of valves and blood flows through it rapidly and with high pressure.