Our body are made up of cells, and aggregate of cells form tissue. Different tissues combine to form organs in the body. In order for the organ to function normally, it requires nutrients and oxygen. This is delivered by blood via tubes in the body called arteries. At the organ, nutrients and oxygen are extracted from the blood through the thin wall of the capillaries. Capillaries are small branches of the arteries and veins and act as the link between them, similar to the numerous carriageways linking the major highways. Blood depleted of nutrients and oxygen is collected by the capillaries and returned to the heart via tubes called veins. The heart (right side) pumps the blood to the lung where the blood will get oxygenated by the lungs. Oxygenated blood is then collected by the heart (left side) and gets pump around the body to keep the body functioning normally. Every part of the body is supplied by both the arteries and the veins. The arteries carries nutrient and oxygen to it and the veins carried waste materials and carbon dioxide from it to be disposed off by the body.
The arteries and veins of the body can be affected by various vascular conditions resulting in blockage (stenosis and occlusion) or enlargement (aneurysm) of the conduits. Blockage in artery results in inability to supply nutrients and oxygen to the organ. Blockage in the vein results in inability to remove excess fluid in the organ causing it to swell up. Enlargement of the wall of the artery cause it to become thin and weak and can result in bursting.