histology of arteries..........explain briefly.
Answers
Answer:
The walls of these arteries have lots of smooth muscle, which means that they are able to contract or relax (dilate) to change the amount of blood delivered, as needed. ... There is a well defined circular layer of smooth muscle in the tunica media. The tunica intima has an endothelium of flattened endothelial cells.
Answer:The walls of arteries are thicker than that of veins to withstand pulsatile flow and higher blood pressures. As arteries become smaller, wall thickness gradually decreases but the ratio of wall thickness to lumen diameter increases (i.e. relative lumen size decreases).
Arteries are divided into three types according to size and function. The constituents of the media of these vessels differ in their relative amounts accordingly.
large elastic arteries (aorta, large aortic branches [e.g. innominate, subclavian, common carotids, iliacs] and pulmonary arteries): the media is abundant in elastic fibers that allow it to expand with systole and recoil during diastole, thereby propelling blood forward
medium-sized muscular arteries (other aortic branches, e.g. coronary and renal arteries): the media is abundant in smooth muscle cells that vasoconstrict or vasodilate, thereby controlling lumen diameter and regional blood flow
small arteries and arterioles (in the substance of organs and tissues): the media is abundant in smooth muscle cells that vasoconstrict or vasodilate; in vessels of this size, smooth muscle contraction causes dramatic changes in lumen diameter, thereby controlling systemic blood pressure as well as regional blood flow