APPLIED ANATOMY OF THE CIRCULATORY SYSTEM 1. HAEMOPHILIA: This is characterized by prolonged bleeding due to deficiency of factor VIII (von Willebrand's factor) in endothelial cells of all blood vessels larger than the capillary. 2. ANEURYSM: This occurs in arteries following weakening of the tunica media, resulting in dilation and rupture. This can leading to spontaneous aortic rupture and sudden death.

3. TUMORS: a.Angiosarcoma: Malignant endothelial cell tumor. b. Haemangiopericytoma: Benign (Innocent) tumor of pericytes. The presence of factor VIII is used to distinguish between a. and b. above.

4. ATHEROSCLEROSIS: This is an abnormality in arteries characterized by:  Thickening of the intima from lipid deposit  Proliferation of smooth muscle cells  Proliferation of connective tissue cells  Deposit of cholesterol in smooth muscles, microphages and myointimal cells**  Ultimate occlusion of vascular lumen. The coronary arteries are the most vulnerable to this lesion.

5. ARTERIOSCLEROSIS: This is the ultimate result of atherosclerosis. As plaques are formed diffusion of nutrients through the vascular wall is impaired and leads to muscle death in the media accompanied by degeneration of elastic tissue. The fibrotic tissue is subsequently calcified. The vessels become rigid and may ulcerate leading to thrombus formation. 6. EDEMA: This is escape of fluids from the circulatory system into tissue spaces and accumulation therein in abnormal situations such as inflammation. This process occurs principally at the junctions between endothelial cells of small venules

7. DIAPEDESIS: This is the escape of Leucocytes from the blood stream into tissue spaces through the junctions between endothelial cells of capillaries and post- capillary venules. It is frequently associated with inflammatory states. 8. PERICYTES IN TISSUE DEFENSE AND REPAIR: Pericytes are involved in tissue defense during which they act as phagocytes. They also proliferate to form new blood vessels (Angiogenesis) and are supportive of the endothelial cells. 9. CARDIAC FUNCTIONS AND IONS Low Potassium and Calcium in blood depresses the heart while excess of Calcium could lead to sustained cardiac muscle contraction resulting in death e.g. (Death by lethal Injection).

10.THROMBOEMBOLISM Thromboembolism is the detachment of a solid mass of a thrombus from the vascular wall into its lumen and its circulation in the vascular system. The circulating thrombus is referred to as an embolus which might get impacted in a small vessel and completely occlude the vessel leading to tissue ischaemia, infarction and ultimately necrosis.