Atherosclerosis And Blood Clotting

Question 1

What is atherosclerosis

Answer 1

Fatty deposits blocking an artery directly or increase its chance of being blocked by a blood clot (thrombosis), limiting or blocking blood supply

Question 2

How is a heart attack caused

Answer 2

Atherosclerosis in the coronary arteries, limits or blocks blood supply to heart muscles meaning oxygen and glucose cannot be transported to cells and tissue can die

Question 3

How does a stroke happen

Answer 3

Atherosclerosis in the arteries supplying the brain, supply of blood to the brain is restricted or blocked causing damage/death to cells in brain

Question 4

Process of atherosclerosis

Answer 4

1. Endothelium(artery wall) becomes damaged and dysfunctional
2. Once inner lining of artery breached there is an inflammatory response, WBCs leave the blood vessel and move into artery wall, WBCs accumulate chemicals from blood(esp cholesterol) and atheroma builds up(fatty deposit)
3. Calcium salts and fibrous tissue build up causing hard swelling on inner wall(plaque), means artery wall loses some of its elasticity
4. Plaque causes lumen to become narrower, more difficult for heart to pump blood around body=high blood pressure= more likely that further plaque will form

Question 5

Risk factors for atherosclerosis

Answer 5

-high blood pressure (can be caused by diet high in salt)
-smoking (toxins from cigarette smoke can damage artery wall)
-high cholesterol, obesity, diabetes
-high alcohol consumption

Question 6

Why do only arteries get atherosclerosis

Answer 6

Blood is at high pressure in arteries so significant chance of damage to the walls, low pressure in veins means less risk of damage to walls

Question 7

Why is rapid blood clotting vital

Answer 7

Seals break in the blood vessel= limits blood loss and prevents entry of pathogens through any open wounds

Question 8

How do platelets change to form blood clot

Answer 8

When they come into contact with damaged vessel wall they form spheres with long thin projections and stick to exposed collagen in wall and to each other to form plug. Also release substances that activate more platelets

Question 9

Describe the clotting cascade

Answer 9

1. Platelets and damaged tissue release thromboplastin(protein)
2. Thromboplastin activates an enzyme that catalysed the conversion of protein prothrombin into enzyme thrombin, vitamin K and calcium ions must be present in blood plasma for this to happen
3. Thrombin catalysed conversion of soluble plasma protein fibrinogen into insoluble protein fibrin
4. Mesh of fibrin forms - traps more platelets and RBCs to form clot