Atherosclerosis and CHD

Ella Middlemiss
Mind Map by Ella Middlemiss, updated more than 1 year ago
Ella Middlemiss
Created by Ella Middlemiss over 3 years ago
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atherosclerosis, stroke, blood clotting, CHD
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Atherosclerosis and CHD
1 What is atherosclerosis
1.1 The disease process that leads to CHD and strokes
1.2 Fatty deposits can either block an artery directly or increase its chance of being blocked by a blood clot (thrombosis)
1.3 The blood supply can be blocked completely and if not restored quickly, the affected cells are permanently damaged
1.3.1 In the coronary arteries, this results in a heart attack (myocardial infarction)
1.3.2 In the arteries supplying the brain it results in a stroke
1.4 An artery can burst where blood builds up behind an artery that's been narrowed as a result of atherosclerosis
2 What happens in atherosclerosis?
2.1 Endothelium becomes damaged and dysfunctional
2.1.1 Endothelial damage results in HBP, which puts extra strain on the layer of cells
2.1.1.1 It might also occur due to some of the toxins from cigarette smoke in the bloodstream
2.1.1.1.1 Once the inner lining of the artery is breached, there's an inflammatory response
2.1.1.1.1.1 White blood cells leave the blood vessel and move into the artery wall
2.1.1.1.1.1.1 These cells accumulate chemicals from the blood, particularly cholesterol
2.1.1.1.1.1.1.1 A fatty deposit builds up, called an atheroma
2.1.1.1.1.1.1.1.1 Calcium salts and fibrous tissue also build up at the site, resulting in a hard swelling called a plaque on the inner wall of the artery
2.1.1.1.1.1.1.1.1.1 The build up of fibrous tissue means that the artery wall loses some of its elasticity - it hardens
2.1.1.1.1.1.1.1.1.1.1 Plaques leads to the lumen narrowing - makes it more difficult to pump blood around the body can lead to a rise in blood pressure
2.1.1.1.1.1.1.1.1.1.1.1 Positive feedback
2.1.1.1.1.1.1.1.1.1.1.1.1 HBP and more plaques
2.1.1.1.1.1.1.1.1.1.1.1.1.1 Endothelial damage in other areas more likely
2.1.1.1.1.1.1.1.1.1.1.2 The fast flowing blood in arteries is under high pressure so there is a significant chance of damage to the walls. The low pressure in he veins means there is less chance of damage to the walls
3 Blood Clotting
3.1 Vital when a blood vessel is damaged
3.2 The blood clot seals the break in the blood vessel and limits blood loss and prevents entry of pathogens through any open wounds
3.3 When platelets (a type of blood cell without a nucleus), come into contact with the damaged vessel wall they change from flattened disks to spheres with long thin projections
3.3.1 Their cell surfaces change, causing them to stick to exposed collagen in the wall and to each other to form a temporary platelet plug. They also release substances that activate more platelets
3.3.1.1 The direct contact of blood with collagen triggers a cascade of chemical changes
3.3.1.1.1 Usually blood doesn't clot inside blood vessels
3.3.1.1.1.1 Platelets don't stick to the endothelium of blood vessels.
3.3.1.1.1.1.1 It is very smooth and has substances on its surface that repel the platelets. However, if there is atherosclerosis and the endothelium is damaged, the platelets come into contact with the damaged surface and any exposed collagen.
3.3.1.1.1.1.1.1 The clotting cascade results in a clot
3.4 Platelets stick to damaged wall and to each other, forming a platelet plug
3.4.1 Thromboplastin release triggers clotting cascade
3.4.1.1 Thromboplastin is released from damaged tissue and from platelets
3.4.1.1.1 Ca2+ and vitamin K in plasma must also be present
3.4.1.1.1.1 Thromboplastin activates an enzyme that catalyses the conversion of the protein prothrombin into a enzyme called thrombin
3.4.1.1.1.1.1 Thombin catalyses the conversion of soluble plasma protein, fibrinogen, into the insoluble protein, fibrin
3.4.1.1.1.1.1.1 A mesh of fibrin forms that traps more platelets and red blood cells to form a clot
4 Coronary Heart Disease
4.1 Narrowing of the coronary arteries limits the amount of oxygen-rich blood reaching the heart muscle
4.1.1 The result may be a chest pain (angina)
4.1.1.1 Angina is usually experienced during exertion when the cardiac muscle is working harder and needs to respire more
4.1.1.1.1 Because the heart muscle lacks oxygen, it's forced to respire anaerobically
4.1.1.1.1.1 Results in chemical changes that trigger pain
4.2 If a fatty plaque ruptures, collagen is exposed which leads to rapid clot formation
4.2.1 The blood supply to the heart may be blocked completely
4.2.1.1 The heart muscle supplied by these arteries doesn't receive blood so it's said to be ischaemic (without blood)
4.2.1.1.1 If the affected muscle cells are starved of oxygen for long they will be permanently damaged
4.2.1.1.1.1 Heart attack or myocardial infarction
5 Stroke
5.1 Supply of blood to the brain briefly interrupted is a mini-stroke
5.2 Blood clot blocks one of the arteries leading to the brain is a full stroke, may be fatal
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