2.7 - Pathology Of Cardiovascular Disease Flashcards
Atherosclerosis
Atherosclerosis is the accumulation of fatty materials (consisting mainly of cholesterol, fibrous material and calcium) forming an atheroma or plaque beneath the endothelium of an artery.
Impact of atheroma on artery
As the atheroma grows, the artery thickens and loses its elasticity. The diameter of the lumen becomes reduced and bloodflow becomes restricted resulting in increased blood pressure
What is atherosclerosis the root cause of
Atherosclerosis is the root cause of various cardiovascular diseases (CVD) such as angina, heart attack, stroke and peripheral vascular disease.
What is angina
Angina is chest pain caused by reduced bloodflow to the heart muscles and is usually caused by coronary heart disease.
Cardiovascular disease – atheroma
Atheromas may rupture leading to damage to the endothelium. This damage releases clotting factors that activate a cascade of reactions that cause a blood clot called a thrombus.
What is thrombosis
Formation of a thrombus
What does the damage to the endothelium release
The damage to the endothelium releases clotting factors that activate a cascade of reactions resulting in the conversion of the enzyme prothrombin to its active form from thrombin.
What does thrombin cause
Thrombin causes molecules of the plasma protein fibrinogen to form threads of fibrin. The fibrin threads form a mesh work that clots the blood, seals the wound and provides a scaffold for the formation of scar tissue.
What is clotting
Clotting is the mechanism that prevents blood loss from broken blood vessels
What can a thrombosis lead to
A thrombosis in a coronary artery may lead to a myocardial infraction, commonly known as a heart attack
What leads to a stroke
A thrombosis in an artery in the brain may lead to a stroke. Cells are deprived of oxygen leading to death of the tissues.
How is an embolus formed
In some cases, a thrombus may break loose forming an embolus which travels through the bloodstream until it blocks a blood vessel.
Stroke
The brain cells need a constant supply of oxygen from the blood.
A stroke means that the blood supply to a part of the brain is suddenly cut off.
Soon after the blood supply is cut off, the cells in the affected area of the brain become damaged or die.
What causes peripheral vascular disease
Peripheral vascular disease is caused by narrowing of the arteries due to atherosclerosis of the arteries other than those of the heart and brain.
Peripheral vascular disease - what arteries are most commonly affected
The arteries in the legs are most commonly affected.
Pain is experienced in the leg muscles due to a limited supply of oxygen.
What is a deep vein thrombosis (DVT)
A deep vein thrombosis is a blood clot that forms in a deep vein most commonly in the leg.
These break off and result/cause a pulmonary embolism.
What causes a pulmonary embolism
A pulmonary embolism is caused when an embolus blocks the pulmonary artery.
This results in chest pain and breathing difficulties.
What is cholesterol
Cholesterol is a fatty substance known as a lipid found in the cell membrane.
It is necessary for normal functioning of the body.
What is cholesterol also used for
Make sex hormones - testosterone, oestrogen and progesterone
Where is cholesterol made
Cholesterol is synthesised by all cells, although 25% of total production takes place in the liver
What causes an increase in cholesterol levels in the blood
A diet high in saturated fats or cholesterol
How is cholestrol transported
Carried in the blood by proteins.
It combines with proteins and forms lipoproteins. (Which is what is carried in the blood)
Types of lipoprotein
High density lipoprotein - HDL.
Low density lipoprotein- LDL
HDL function
HDL transports excess cholesterol from the body cells to the liver for elimination which prevents the accumulation of cholesterol in the blood.
LDL function
LDL transports cholesterol to body cells
LDL receptors and cells
Most cells have LDL receptors that take LDL into the cell where it releases cholesterol. Once a cell has sufficient cholesterol, a negative feedback system inhibits the synthesis of new LDL receptors and LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas.
HDL to LDL ratio
A higher ratio of HDL to LDL will result in lower blood cholesterol and reduced chance if atherosclerosis.
What causes an increase in blood
cholesterol levels
A diet high in saturated fats or cholesterol
What raises HDL
Regular physical activity
What do dietary changes aim to do?
Reduce the levels of total fat in the diet and to replace saturated with unsaturated fats.
Drugs and cholesterol levels
Drugs such as statins reduce blood cholesterol by inhibiting the synthesis of cholesterol by liver cells.
