Atherosclerosis

Question 1

What is atherosclerosis?

Answer 1

Hardness of arteries

Caused by fatty deposits on the inner walls of the arteries

Question 2

Risk factors for atherosclerosis?

Answer 2

Age: the older you get the more fatty deposits

Tobacco smoking

High serum cholesterol

Obesity

Diabetes

Hypertension

Family history

Question 3

Where are atherosclerotic plaques distributed?

Answer 3

Arteries! peripheral, coronary

Question 4

What determines where atherosclerotic plaques develop?

Answer 4

Haemodynamic factors

Changes in flow / turbulence cause arteries to change their wall thicknesses and develop neointima

Question 5

What is neointima?

Answer 5

Scar tissue that forms within vessel walls

Question 6

How does hypertension cause atherosclerosis?

Answer 6

Higher pressure, more strain on vessel walls

Question 7

How does smoking cause atherosclerosis?

Answer 7

Smoking causes injury to blood vessel walls, causing damage to endothelial cells which is the first step towards atherosclerosis

Question 8

Describe the structure of an atherosclerotic plaque?

Answer 8

Lipids
Necrotic core
Connective tissue
Fibrous cap

Question 9

What complications occur as a result of atherosclerosis?

Pathophysiology behind this?

Answer 9

Thrombosis formation - Virchow’s triad

1. endothelial injury
2. stasis of blood flow
3. hypercoagulability

Narrowing of vessels due to atheromas

Ischaemia, infarction

Question 10

How does obesity cause atherosclerosis?

Answer 10

Fat in the pericardium, that causes the release of proteins that cause inflammation

Question 11

How does diabetes cause atherosclerosis?

Answer 11

High blood glucose = damage to endothelium, which is the 1st step towards atherosclerosis

Question 12

Desrcibe the process of atherogenesis.

Answer 12

Injury to endothelial cells - endothelial dysfunction
(caused by smoking, virus, high blood sugar etc.)

Injury causes signals to be sent to circulating leukocytes which then accumulate at the area and cause atherosclerotic build up

Question 13

What is ischaemia-reperfusion injury?

Answer 13

If a tissue is starved of blood and therefore oxygen, when the blood supply returns to the area it can cause damage

Inflammation and oxidative damage occurs because of the environment created when it was lacking in nutrients and oxygen

Neutrophils can enter the damaged area and can sometimes cause more damage

Question 14

What’s the difference between HDLs and LDLs?

What are they?

Answer 14

HDLs - high density lipoprotein
LDLs - low “”

They are proteins that transport cholesterol around the body

Question 15

What do LDLs do?

Answer 15

Carry cholesterol from liver to cells

Bad, because they cause fatty deposits to build up in the wrong places, ie. endothelial cells

Question 16

What do HDLs do?

Answer 16

Transport cholesterol from the cells to the liver

Good

Question 17

List the 5 stages of atherosclerosis plaque progression.

Answer 17

1. Fatty streaks
2. Intermediate lesions
3. Fibrous plaques/advanced lesions
4. Plaque rupture
5. Plaque erosion

Question 18

When do fatty streaks first start to appear?

Answer 18

At about age 10

Question 19

What are fatty streaks made of?

Answer 19

Lipid laden macrophages

and T lymphocytes

Question 20

Where are the fatty streaks?

Answer 20

In the intimal layer of the vessel wall

Question 21

What do intermediate lesions consist of?

Answer 21

Lipid laden macrophages

Vascular smooth muscle cells

T lymphocytes

Adhesion of platelets to vessel wall

Isolated pools of extracellular lipid

Question 22

Where are the intermediate lesions?

Answer 22

In the intimal layer of the vessel wall

Question 23

What do the fibrous plaques consist of?

Answer 23

They are intermediate lesions but with a fibrous cap

Fibrous plaques are made of extracellular proteins (collagen, elastin) laid down by smooth muscle cells

The centre of the plaque starts to become necrotic

The plaque becomes calcified

Question 24

At what stage does the plaque get a fibrous cap?

Answer 24

Stage 3: when they become fibrous plaques/advanced lesions

Question 25

Plaques are constantly growing and receding. True or false?

Answer 25

True!

The fibrous cap has to be resorbed and re-deposited so it can be maintained

Question 26

What makes the plaques rupture?

Answer 26

Inflammatory conditions

Increased enzyme activity

Question 27

What happens when the plaque ruptures?

Answer 27

The fibrous cap comes off

Revealing the basement membrane, collagen, necrotic tissue

Causing vessels within the plaque to haemorrhage

This leads to a thrombus and vessel occlusion