Atherosclerosis Flashcards
What is blood clotting also known as?
Thrombosis
When will a blood clot form in an artery?
When the blood vessel walls are damaged or when blood flows very slowly
What is the first stage in blood clotting?
Platelets stick to the damaged vessel and thromboplastin (enzyme) is released from the damaged tissue and platelets
What does thromboplastin need to work?
Calcium and vitamin K (carried in plasma)
What does thromboplastin change?
Prothrombin into thrombin (an enzyme)
What does thrombin change?
Soluble fibrinogen into insoluble fibrin
What do these platelets form over the damaged vessel
A platelet plug
How is the clot formed?
A fibrin mesh traps blood cells, forming a clot
Where does atherosclerosis normally occur?
In major arteries
What three things normally causes damage to the endothelium layer?
High blood pressure, toxins from cigarette smoke or an infection e.g. chlamydia
What happens to the vessel when the endothelium layer is damaged?
An inflammatory response is triggered
What happens when there is an inflammatory response?
White blood cells move into the vessel wall and lipids i.e. cholesterol enter the vessel wall
Why are the white blood cells actually making the situation worse?
because they engulf the lipids trapped in the wall and try to destroy them, they can’t break the lipids down so a fatty deposit builds up
What is formed because of the white blood cells and lipids?
An atheroma
How is a plaque formed?
calcium salts and fibrous tissue build up in the vessel wall so a hard swelling (plaque) forms.
Does the vessel become more/less elastic because of this plaque?
The vessel loses some of its elasticity
What happens to the lumen because of the plaque?
The lumen becomes narrower, it is now called an advanced lesion
How is a positive feedback loop created?
Because of the lumen becoming narrower its more difficult for the heart to pump blood therefore blood pressure is raised and the whole cycle starts all over again
What are some consequences of atherosclerosis?
Angina, CHD, Stroke and aneurysms
Why is angina caused?
Because the heart muscle lacks oxygen, it is forced to respire anaerobiclly - causing chest pain
How is an aneurysm formed?
Because the artery has lost elasticity blood can build up behind it, the artery then bulges as it fills with blood and an aneurysm forms.
When is an aneurysm likely to rupture?
At 6-7cm in diameter
