Key Area 7- Pathology of Cardio Vascular Disease (CVD) Flashcards
What is atherosclerosis?
The accumulation of fatty material, consisting mainly of cholesterol, fibrous material and calcium, which forms a plaque, which is called an atheroma, which forms beneath the endothelium
What is atheroma?
A plaque which forms beneath the endothelium due to atherosclerosis
What happens over time to the atheroma?
It may grow, causing the plaque to become enlarged as fibrous material, calcium and more cholesterol are added, which makes the atheroma larger.
What are the consequences of the atheroma?
. As the atheroma grows, the artery thickens and loses its elasticity
. The diameter of the artery’s lumen is reduced
. Blood flow becomes restricted to the capillary bed that the artery supplies
.Increased blood pressure
. Hardening of the arteries
What cardiovascular diseases is atherosclerosis the root cause of?
Angina, heart attack, stroke and peripheral vascular disease
How is a thrombus formed?
An atheroma on the inside lining of an artery may rupture, which damages the endothelium and leads to the formation of a thrombus.
What is the first step in the formation of a thrombus?
If an atheroma ruptures and damages the endothelium then, blood clotting factors, which is a protective device to prevent the loss of blood at a wound, are released. This activates a cascade of reactions resulting in the conversion of the enzyme prothrombin into thrombin
What is the second step in the formation of a thrombus?
Thrombin causes molecules of fibrinogen, a plasma protein, to form threads of fibrin
What is the third step in the formation of a thrombus?
Fibrin threads from a meshwork that clots the blood, and seals the wound providing a scaffold for the formation of scar tissue
What is the formation of a thrombus/clot called?
Thrombosis
What is an embolus?
If the thrombus breaks lose and form an embolus, which travels down the bloodstream until it blocks a blood vessel and restricts blood flow
What can thrombosis in a coronary artery lead to?
It may lead to a heart attack, myocardial infarction, because it blocks the coronary artery
What can thrombosis the brain lead to?
A stroke, if it causes blockages in an artery to the brain
What happens if cells in the brain are deprived of oxygen?
Brain tissues can die
What is peripheral vascular disease?
The narrowing of the arteries, of arteries other than those to the heart and the brain, due to atherosclerosis
What arteries are most commonly affected by peripheral vascular disease?
Arteries to the legs. The blood flow to the legs is restricted and pain is felt due to a limited supply of oxygen reaching the leg muscles
What is a deep vein thrombosis (DVT)?
A blood clot/thrombus that forms in a deep vein, most commonly in the leg.
What does DVT cause?
It causes the area to be painful, swell up and veins close to the skin surface can become engorged with blood
What happens if the deep vein thrombosis breaks off?
The blood clot can break off and travel through the blood stream and result in a pulmonary embolism in the lungs as the embolus/blood clot can block a pulmonary artery
What can a pulmonary embolism cause?
Chest pains, breathing difficulties and palpitations
What are lipids?
They are a diverse group of organic compounds which include simple lipids, such as fats, and more complex lipids, such as steroids
Where is cholesterol located?
Its located in the cell membrane
Why is cholesterol important?
Because it is needed for the synthesis of the sex hormones testosterone, oestrogen and progesterone
What are lipoproteins?
They are molecules containing a combination of lipid and protein
Where are lipoproteins found?
They are found in the blood plasma which transports the lipids from one part of the body to another
What are the two major transport lipoproteins?
High density lipoproteins (HDL) and low density lipoproteins (LDL)
What do HDL’s transport and what does this prevent?
They transport excess cholesterol from the body tissues to the liver to be broken down and eliminated. This prevents the accumulation of cholesterol in the blood, which lowers blood cholesterol levels and helps remove plaque so doesn’t contribute to atherosclerosis
.They are known as ‘good cholesterol’
What are LDL’s produced by?
The liver
What do most cells have?
LDL receptors which take LDL into the cell where it releases cholesterol
What is the negative feedback control of LDL’s?
. If a cell has sufficient cholesterol, a negative feedback system is triggered which inhibits the synthesis of new LDL receptors
.LDL circulates in the blood where it may deposit in the arteries forming atheromas
What will a higher ratio of HDL to LDL result in?
A lower blood cholesterol and a reduced chance of atherosclerosis
What are the treatments for raising HDL levels and lowering LDL levels?
. Dietary changes which aim to reduce the levels of total fat in the diet and to replace saturated fats with unsaturated fats
. Regular physical activity tends to raise HDL levels
What are drugs for rasing HDL levels and lowering LDL levels?
. Reducing blood cholesterol through prescribed medications
. Drugs such as ‘statins’ reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells
