Tunica Externa Outermost layer of the blood vessel

Tunica Externa �Outermost layer of the blood vessel �Composed of loose connective tissue

Tunica media �Middle layer of the blood vessel �Consist primarily of circumferentially arranged layers of smooth muscle

Tunica intima �Innermost layer of the blood vessel �Single layer of endothelial cells

Endothelial Cells �Maintenance of a selective permeability barrier �Regulation of thrombosis �Modulation of blood flow and vascular reactivity �Regulation of cell growth, particularly smooth muscle cells �Regulation of inflammatory/immune responses �Maintenance of extracellular matrix �Involvement in lipoprotein metabolism

Endothelial Dysfunction �Cytokines, bacterial, and viral products causing inflammation �Hemodynamic stresses and lipid products (Lends to pathologic process of atherosclerosis) �Hypoxia �Influence the reactivity of smooth muscle cells both relaxing and contracting factors �Produce other �cytokines, �growth factors, � procoangulant or anticoagulant substances

Vascular Smooth Muscle Cells �Control dialation and vasoconstriction of blood vessels �Control elaborate growth factors �Synthesize collagen, elastin, and other components of vascular repair �Function lends to the normal vascular repair �Lends to pathologic process of atherosclerosis