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Coronary Heart Disease

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Queen's University
BIOL 201
Elaine Power

Coronary Heart Disease  Arteries supplying the heart become narrowed and the blood supply to cardiac tissues is reduced  Heart has to work harder to force blood through narrowed vessels / blood pressure increases  Angina o Chest pain due to severe shortage of blood to the heart muscle - cells do not die o Pain only occurs during activity but not at rest o Caused by narrowing of coronary arteries (atherosclerosis)  Heart attack (myocardial infarction) o When a coronary artery is totally blocked by a thrombus/embolus o No blood supply to heart muscle and cells die - often fatal  Heart failure o Blockage leads to damage of heart muscle and to gradual weakening of muscle o Less efficient pumping o Often accumulation of blood on right side → enlargement of heart Causes of Coronary Heart Disease  The main cause is atherosclerosis  Often called hardening of the arteries  Inner layer of artery wall thickens with deposits of o Cholesterol o Fibrous (scar) tissue o Dead muscle cells o Blood platelets  Fats, in the form of lipoproteins, accumulate beneath the endothelium o Form plaque on the wall of arteries, also called atheroma o Arteries become less elastic and partially narrowed o Accelerated by high blood pressure o Arterial endothelium damage is more likely but also leads to further weakening  Aneurysm: weak walls may burst leading to severe loss of blood (haemorrhaging) o Brain aneurysm is called a stroke  Atheroma increases the risk of blood clotting o Thrombus (blood clot) may break away and lodge elsewhere in the circulation (e.g. brain, heart) o Circulating thrombus is called an embolus Cholesterol and Atherosclerosis  Cholesterol
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