Atherosclerosis and Blood Clotting

Question 1

What is atherosclerosis? (include Greek meaning)

Answer 1

• ‘athero’ refers to mush and ‘sclerosis’ means the hardening
• atherosclerosis refers to the hardening of the arteries due to the accumulation of lipids (particularly cholesterol)
• atherosclerosis is the disease process that leads to coronary heart disease and strokes

Question 2

What does accumulation mean? How does this link to atherosclerosis?

Answer 2

• accumulation is an amount of something that has gradually increase over time
• atherosclerosis is a progressive disorder (it gets worse over time) and lipids are accumulated

Question 3

Summarise what happens in atherosclerosis

Answer 3

In atherosclerosis, fatty deposits can either block an artery directly or increase its chance of being blocked by a blood clot (thrombosis)

Question 4

What is thrombosis? How can it be triggered?

Answer 4

Thrombosis is the formation of a blood clot inside a blood vessel
it can be triggered by a bursting atheroma

Question 5

What is an atheroma and what causes it to form?

Answer 5

• An atheroma is a build up of fatty deposits (made up of cholesterol and other lipids) in the wall of an artery
• It forms when there is damage to the endothelium, which triggers an inflammatory response

Question 6

What is an inflammatory response?

Answer 6

the inflammatory response is a localised defence mechanism

Question 7

What happens if blood supply is not restored very quickly?

Answer 7

If blood supply is not restored very quickly then the affected cells are permanently damaged

Question 8

What is myocardial infarction? And what leads to it?

Answer 8

If the coronary arteries have no blood supply, this results in a heart attack (myocardial infarction)

Question 9

What is a stroke? And what can lead to a stroke?

Answer 9

• When the supply of blood to the brain is restricted or blocked, this results in a stroke
• a stroke is the sudden death of brain cells (in a localised area) due to inadequate blood flow

Question 10

What is positive feedback? Give an example?

Answer 10

• positive feedback is a process in which the end products of an action cause more of that action to occur in a feedback loop
• atherosclerosis is an example of positive feedback

Question 11

How can an artery burst?

Answer 11

an artery can burst when blood builds up behind the artery (this can result in internal bleeding)

Question 12

What is an aneurysm?

Answer 12

this is where the artery wall is weakened so much that the blood pressure causes it to deform or even burst

Question 13

What is endothelium?

Answer 13

endothelium is a delicate layer of cells that line the inside of the artery and separates the blood flow from the muscular wall

Question 14

What is stage 1 of atherosclerosis?

Answer 14

• the endothelium that lines the inside of an artery becomes damaged
• this could be due to high blood pressure or maybe due to chemicals from cigarette smoke

Question 15

What is stage 2 of atherosclerosis?

Answer 15

• this damage causes an inflammatory response
• as a result white blood cells accumulate chemicals from the blood, particularly cholesterol
• a fatty deposit builds up called an atheroma

Question 16

What is stage 3 of atherosclerosis?

Answer 16

• fibrous tissue and calcium salts build up
• this results in a hard swelling called a plaque (on the inner wall of the artery)
• the artery wall loses some of its elasticity

Question 17

What is stage 4 of atherosclerosis?

Answer 17

• plaques cause the artery lumen to become narrow
• it is now harder for the heart to pump blood through the narrowed artery
• and the blood pressure increases
• this is called positive feedback, increasing the risk of more damage to the artery wall and therefore more atherosclerotic plaques

Question 18

What is stage 1 of the blood clotting process?

Answer 18

• collagen is exposed when wall of blood vessel is damaged
• platelets come into contact with collagen (damaged wall) and stick to it and to each other forming a platelet plug

Question 19

What is stage 2 of the blood clotting process?

Answer 19

• thromboplastin is released from damaged cells and platelets
• thromboplastin (plus Ca2+ and vitamin K present in plasma) cause a cascade of chemical changes

Question 20

What is stage 3 of the blood clotting process?

Answer 20

• (thromboplastin catalyses) conversion of Prothrombin to the enzyme thrombin
• thrombin then catalyses conversion of the soluble protein fibrinogen into the insoluble fibrin

Question 21

What is stage 4 of the blood clotting process?

Answer 21

• fibrin then forms a tangled mesh
• red blood cells and platelets are trapped in the tangled mesh, forming a blood clot