1) The wall of the artery is made up of several layers
2) The endothelium (inner lining) is usually smooth and unbroken
3) If damage occurs to the endothelium (e.g. by high blood pressure), white blood cells (mainly macrophages) and lipids (fat) from the blood clump together under the lining to form fatty streaks
4) Over time, more white blood cells, connective tissue and lipids build up and harden to form a fibrous plaque called an atheroma
5)The plaque partially blocks the lumen of the artery and restricts blood flow, which causes blood pressure to increase
Aneurysm - a balloon-like swelling of the artery
1)Atheroma plaques damage and weaken arteries. They also narrow them, increasing blood pressure
2)When blood travels through a weakened artery at high pressure, it may push the inner layers of the artery through the outer elastic layer to form a balloon-like swelling - an aneurysm
3)This aneurysm may burst, causing a haemorrhage (bleeding)
Thrombosis - formation of a blood clot
1)An atheroma plaque can rupture (burst through) the endothelium (inner lining) of an artery
2)This damages the artery wall and leaves a rough surface
3)Platelets and fibrin (a protein) accumulate at the site of the damage and form a blood clot/thrombus
4)This blood clot can cause a complete blockage of the artery, or it can become dislodged and block a blood vessel elsewhere in the body.
5)Debris from the rupture can cause another blood clot to form further down the artery
Interrupted blood flow to the heart can cause a myocardial infarction
1)The heart muscle is supplied with blood by the coronary arteries
2)This blood contains the oxygen needed by the heart muscle cells to carry out aerobic respiration.
3)If a coronary artery becomes completely blocked (e.g. by a blood clot) an area of heart muscle will be totally cut off from its blood supply, receiving no oxygen.
4)This causes a myocardial infarction - or heart attack
5)A heart attack can cause damage and death of the heart muscle
6)Symptoms include pain in the upper chest and body, shortness of breath and sweating
7)If large areas of the heart are affected complete heart failure can occur, which is often fatal