atheroma

Question 1

what is Atherosclerosis?

Answer 1

Inflammatory process characterised by hardened plaques in the intima of systemic arteries

Question 2

in which vessels does Atherosclerosis tend to take place?

Answer 2

• in the intima of large and medium-sized systemic arteries (a higher pressure system)
• not pulmonary arteries

Question 3

what is the main risk of Atherosclerosis?

Answer 3

The increased pressure and inflammation can cause the plaque to rupture.
A thrombus forms on the disrupted plaque (platelets adhere and clotting process begins)
blood flow can be impeded

OR the plaque occludes the artery and can cause angina

Question 4

what are common sites affected by Atherosclerosis?

Answer 4

coronary arteries, carotid arteries, renal arteries, aorta, or in peripheral arteries

Question 5

when do complications of atherosclerotic plaques tend to occur in life?

Answer 5

40s-80s

Question 6

list 5 non-modifiable risk factors to Atherosclerosis

Answer 6

Age
Gender
Race
Family History
poorly controlled Diabetes (Type 1)

Question 7

list 5 modifiable risk factors to

Answer 7

Smoker
Lack of exercise
Weight
(Borderline) Diabetes (type 2)
Hypertension
High cholesterol (Hypercholesterolemia)

low SES?

Question 8

what are the main constituents of an atherosclerotic plaque

Answer 8

predominantly Lipids
Necrotic core
Connective tissue
Fibrous “cap”
lymphocytes

Question 9

in short, what is the Main reason atherosclerotic plaques can form?

Answer 9

the endothelial cell damage theory

Question 10

what are the 3 main headings to plaque formation:

Answer 10

1. damage to endothelial cells
2. LDLs start fatty streak formation
3. foam cells products and contents cause plaque growth

Question 11

in what layer of the artery does the atherosclerotic plaque form?

Answer 11

the tunica intima

Question 12

list some common outcomes of atherosclerosis

Answer 12

• aortic aneurysm
• myocardial infarct

Question 13

explain step 1 in plaque formation

1.damage to endothelial cells

Answer 13

Due to high levels of LDLs in blood stream (hyperlipidemia)
Smoking or air pollution (free radicals)
High cholesterol
Hypertension - causes physical injury
Turbulent blood flow, for example, where arteries branch
Chronically elevated blood glucose levels

Question 14

explain step 2 in plaque formation

2. LDLs start fatty streak formation

Answer 14

Dysfunctional endothelial cells allow Low density lipoproteins (LDLs) to move from lumen into tunica intima layer

The Dysfunctional cells release reactive oxygen species (eg. metalloproteases) which oxidise the LDLs

Oxidised LDLs cannot leave the intima, they are trapped

Dysfunctional endothelial cells + oxidised LDLs trigger endothelial cells to express adhesion molecules for WBCs (monocytes + T helper cells)

These monocytes attach and move into intima where they are now called macrophages

Macrophages have scavenger receptors that will engulf the oxidised LDLs to become a foam cell

A fatty streak has formed

Question 15

explain step 3 in plaque formation

3. foam cells products and contents cause plaque growth

Answer 15

Foam cells release products, then die and release contents. this forms the fibrous cap, the bulk of the plaque and increases inflammation.

Products released:

-chemokines, to attract more macrophages
IGF-1 ( a growth factor), that causes smooth muscle cells to proliferate and migrate from the media to the intima layer. These cells make collagen, which forms a hard, fibrous cap to the plaque

-proinflammatory cytokines and reactive oxygen species increase inflammation

-When the foam cells die they release lipid content, containing DNA materials which attract neutrophils to the site of Inflammation

Question 16

what 2 factors cause plaque growth and increased inflammation

Answer 16

1. increased vascular supply to plaque
2. T cells

• T cells bind onto the endothelial cells,
  -enter plaque area,
  -activated by macrophages to release IFN-Y
• this promotes inflammation and activates endothelial cells to attract more WBCs
  -therefore plaque keeps growing and there is inflammation

Question 17

What can be done to prevent atherosclerosis?

Answer 17

Reduce risk factors and taking low dose aspirin regularly.

Question 18

Why can cigarette smoking lead to atherosclerosis?

Answer 18

Cigarette smoking releases free radicals, nicotine and CO into the body. These all damage endothelial cells.

Question 19

Why can hypertension lead to atherosclerosis?

Answer 19

A higher blood pressure means there is a greater force exerted onto the endothelial cells and this can lead to damage.