MICROANATOMY

Detailed explanation-1: -Arteries and arterioles have relatively thick muscular walls because blood pressure in them is high and because they must adjust their diameter to maintain blood pressure and to control blood flow.

Detailed explanation-2: -Myocardium – a thick, muscular middle layer that contracts and relaxes to pump blood around of your heart. Endocardium – a thin, inner layer that makes up the lining of the four chambers and the valves in your heart.

Detailed explanation-3: -Muscular arteries contain more smooth muscle cells in the tunica media layer than the elastic arteries. Elastic arteries are those nearest the heart (aorta and pulmonary arteries) that contain much more elastic tissue in the tunica media than muscular arteries.

Detailed explanation-4: -Arteries have thick elastic walls and veins have valves.

Detailed explanation-5: -Arteries and arterioles have thicker walls than veins and venules because they are closer to the heart and receive blood that is surging at a far greater pressure (Figure 2). Each type of vessel has a lumen-a hollow passageway through which blood flows.