important role is to regulate the movement of materials into and out of cells. The phospholipid bilayer structure (fluid mosaic model) with specific membrane. proteins accounts for the selective permeability of the membrane and passive. and active transport mechanisms.
Structure of Blood Vessels a) Three distinct layers or tunics form the walls of blood vessels: ---The tunica interna (tunica intima) is the innermost layer.It contains the endothelium which is a continuation of the endocardial lining of the heart.tructure of Blood Vessels a) Three distinct layers or tunics form the walls of blood vessels: ---The tunica interna (tunica intima) is the innermost layer.
The arteries are the blood vessels that deliver oxygen-rich blood from the heart to the tissues of the body. Each artery is a muscular tube lined by smooth tissue and has three layers: 1  The intima, the inner layer lined by a smooth tissue called endothelium.onditions of the Arteries. 1  Atherosclerosis: The buildup of cholesterol (a waxy substance) into what are called plaques in the arteries' walls. 2  Atherosclerosis in the arteries of the heart, brain, or neck can lead to heart attacks and strokes.