Biology 5.3 Heart Disease

Coronary heart disease = CHD.

CHD = affects coronary arteries, blood flow may be impaired by build-up of fatty deposits, can lead to myocardial infarcation.

Atheroma

Atheroma = fatty deposit, forms WITHIN wall of an artery.

Begins as fatty streaks (accumulations of white blood cells that have taken up low-density lipoproteins) that enlarge to form irregular patch known as atheromatous plaque.

Atheromatous plaques more commonly occur in larger arteries, made up of deposits of cholesterol, fibres and dead muscle cells - bulge into lumen of artery, narrowing it, blow flow is reduced.

Atheromas increase risk of thrombosis and aneurysm.

Thrombosis

Thrombus = blood clot, forms if atheroma breaks through lining of blood vessel (endothelium) and forms a rough surface that interrupts the flow of blood.

Thrombus may block blood vessel, reducing or preventing supply of blood to tissues beyond - tissue deprived of blood (hence oxygen, glucose etc) often dies. 

Aneurysm

Weakened artery walls (from atheromas and thrombosis) can swell to form a balloon-like, blood-filled structure = aneurysm. 

Aneurysms frequently burst, leads to haemorrhage, loss of blood to region of body served by artery. Brian aneurysm = stroke.

Myocardial Infarction

= Heart attack, caused by reduced supply of oxygen to the heart muscle from blockage coronary arteries.

If blockage is close to junction of coronary artery and aorta, heart will stop beating…