Atherosclerosis Flashcards
What is atherosclerosis?
Hardness of arteries
Caused by fatty deposits on the inner walls of the arteries
Risk factors for atherosclerosis?
Age: the older you get the more fatty deposits
Tobacco smoking
High serum cholesterol
Obesity
Diabetes
Hypertension
Family history
Where are atherosclerotic plaques distributed?
Arteries! peripheral, coronary
What determines where atherosclerotic plaques develop?
Haemodynamic factors
Changes in flow / turbulence cause arteries to change their wall thicknesses and develop neointima
What is neointima?
Scar tissue that forms within vessel walls
How does hypertension cause atherosclerosis?
Higher pressure, more strain on vessel walls
How does smoking cause atherosclerosis?
Smoking causes injury to blood vessel walls, causing damage to endothelial cells which is the first step towards atherosclerosis
Describe the structure of an atherosclerotic plaque?
Lipids
Necrotic core
Connective tissue
Fibrous cap
What complications occur as a result of atherosclerosis?
Pathophysiology behind this?
Thrombosis formation - Virchow’s triad
- endothelial injury
- stasis of blood flow
- hypercoagulability
Narrowing of vessels due to atheromas
Ischaemia, infarction
How does obesity cause atherosclerosis?
Fat in the pericardium, that causes the release of proteins that cause inflammation
How does diabetes cause atherosclerosis?
High blood glucose = damage to endothelium, which is the 1st step towards atherosclerosis
Desrcibe the process of atherogenesis.
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
What is ischaemia-reperfusion injury?
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
What’s the difference between HDLs and LDLs?
What are they?
HDLs - high density lipoprotein
LDLs - low “”
They are proteins that transport cholesterol around the body
What do LDLs do?
Carry cholesterol from liver to cells
Bad, because they cause fatty deposits to build up in the wrong places, ie. endothelial cells
What do HDLs do?
Transport cholesterol from the cells to the liver
Good
List the 5 stages of atherosclerosis plaque progression.
- Fatty streaks
- Intermediate lesions
- Fibrous plaques/advanced lesions
- Plaque rupture
- Plaque erosion
When do fatty streaks first start to appear?
At about age 10
What are fatty streaks made of?
Lipid laden macrophages
and T lymphocytes
Where are the fatty streaks?
In the intimal layer of the vessel wall
What do intermediate lesions consist of?
Lipid laden macrophages
Vascular smooth muscle cells
T lymphocytes
Adhesion of platelets to vessel wall
Isolated pools of extracellular lipid
Where are the intermediate lesions?
In the intimal layer of the vessel wall
What do the fibrous plaques consist of?
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
At what stage does the plaque get a fibrous cap?
Stage 3: when they become fibrous plaques/advanced lesions
Plaques are constantly growing and receding. True or false?
True!
The fibrous cap has to be resorbed and re-deposited so it can be maintained
What makes the plaques rupture?
Inflammatory conditions
Increased enzyme activity
What happens when the plaque ruptures?
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
