CVD Flashcards
(38 cards)
Cardiovascular Diseases - CVD
One of the main processes leading to CVD are Atherosclerosis and Hypertension
Cardiovascular disease is a group of diseases of the heart and blood vessels. The main examples include:-
Peripheral Vascular Disease
Angina
Myocardial infarction (heart attack)
Stroke
Atherosclerosis
Atherosclerosis is the accumulation of fatty material (consisting mainly of cholesterol), fibrous material and calcium forming an atheroma or plaque beneath the endothelium
Atheromas=Plaque
As the atheroma grows the artery thickens and loses its elasticity. The diameter of the artery’s lumen becomes reduced and blood flow becomes restricted resulting in increased blood pressure
Reactions which form a clot
Damage to cell = clotting factors released by the cell.
Prothrombin = an inactive enzyme present in blood plasma.
Clotting factors convert prothrombin into its active form = thrombin.
Thrombin turns a soluble plasma protein = fibrinogen into threads of insoluble protein called fibrin.
Fibrin threads interweave = platelets stick to the fibrin threads = Blood clot/thrombus
Wound sealed and scar tissue forms.
Thrombosis
Atheromas make the surface of the inner artery uneven = restrict blood flow
-Atheromas enlarge and eventually burst through the endothelium and damage it.
-Platelets can attach to rough inner surface of an artery caused by atherosclerosis and release clotting factors.
-This causes a thrombus (blood clot).
-The formation of a clot is referred to as a thrombosis.
Thrombosis pt2
-In some cases a thrombus may break loose forming an embolus and travel through the bloodstream until it blocks a blood vessel.
-A thrombosis in a coronary artery may lead to a heart attack (MI).
-A thrombosis in an artery in the brain may lead to a stroke.
-Cells are deprived of oxygen leading to death of the tissues
Peripheral Vascular Disorders
Peripheral arteries = those other than coronary arteries, carotid arteries (going to brain) and aorta.
-Peripheral vascular disease is narrowing of the arteries due to atherosclerosis of arteries other than those of the heart or brain.
-The arteries to the legs are most commonly affected.
-Pain is experienced in the leg muscles due to a limited supply of oxygen.
Deep Vein Thrombosis
A DVT is a blood clot that forms in a deep vein most commonly in the leg, and can break off and result in a pulmonary embolism.
Cholesterol
Cholesterol is a type of LIPID FOUND IN cell membranes
It is also used to make the sex hormones, testosterone, oestrogen and progesterone.
Cholesterol is synthesised by all cells, although 25% of total production takes place in the liver.
A diet high in saturated fats or cholesterol causes an increase in cholesterol levels in the blood.
Lipoproteins
Molecules made of lipid and protein.
Present in blood plasma.
Transport lipids [including cholesterol] around the body.
2 Main groups = Low–Density Lipoproteins [LDL’s] Bad Cholesterol and High-Density Lipoproteins [HDL’s] Good Cholesterol.
Low Density Lipoprotein
-LDL transports cholesterol from the LIVER to the BODY CELLS
-Most cells have LDL receptors ON THEIR CELL MEMBRANES that take LDL into the cell where it releases cholesterol.
-Cholesterol used within the cell (CELL MEMBRANES/SEX HORMONES)
When a cell has sufficient Cholesterol
Once a cell has sufficient cholesterol a negative feedback system INHIBITS the synthesis of new LDL receptors =
LDL circulates in the blood where it may deposit cholesterol in the arteries forming an atheroma = BAD
High Density Lipoproteins
-HDL transports excess cholesterol from the body cells to the liver for elimination.
-This prevents accumulation of cholesterol in the blood.
HDL cholesterol does not build up in the artery walls as it is not taken in.
-Regular physical activity tends to raise HDL levels.
-Dietary changes aim to reduce the levels of total fat in the diet and to replace saturated with unsaturated fats.
Once cholesterol levels rise
Once a cell has sufficient cholesterol a negative feedback system inhibits the synthesis of new LDL receptors.
LDL circulates in the blood where it may deposit cholesterol in the arteries forming atheromas
Maintaining a healthy Lipoprotein balance
-Normally HDL molecules carry 20-30% of blood cholesterol with LDL molecules carrying 60-70%
-A higher ratio of HDL to LDL molecules = decrease in blood cholesterol = reduced risk of atherosclerosis
-The reverse of this is true with a lower HDL to LDL ratio.
Statins
-Statins help to reduce the level of cholesterol in the blood.
-They inhibit an enzyme [competitive inhibition] that is essential for the synthesis of cholesterol in the liver.
-Statins also increase the number of LDL receptors made by liver cells = more LDL [bad cholesterol] removed from the bloodstream.
Blood glucose levels and vascular disease
Normal blood plasma = 5 mmol/l of glucose.
Person with untreated diabetes = blood glucose level rises to 30 mmol/l. This is an abnormal and chronic level.
Microvascular disease
-Chronic elevation of blood glucose levels leads to the endothelium cells taking in more glucose than normal, damaging the blood vessels.
-Atherosclerosis may develop leading to cardiovascular disease, stroke or peripheral vascular disease.
-Small blood vessels damaged by elevated glucose levels may result in haemorrhage of blood vessels in the retina, renal failure or peripheral nerve dysfunction.
Regulating blood glucose levels
All living cells require a supply of glucose for respiration.
The liver can store up to 100 grams of glucose in the form of glycogen.
Glucose can be removed from the liver if the body’s cells demand it.
2 important hormones are produced to help control blood glucose levels = insulin and glucagon
The role of insulin
Pancreatic receptors respond to raised blood glucose levels by increasing secretion of insulin from the pancreas.
Insulin activates the conversion of glucose to glycogen in the liver decreasing blood glucose concentration.
Glucagon
Pancreatic receptors respond to lowered blood glucose levels by increasing secretion of glucagon from the pancreas.
Glucagon activates the conversion of glycogen to glucose in the liver increasing blood glucose concentration.
Glucose levels during exercise
During exercise and fight or flight responses, glucose concentrations in the blood are raised by adrenaline, released from the adrenal glands, stimulating glucagon secretion and inhibiting insulin secretion.
Diabetes
A person with diabetes is unable to control their blood glucose levels.
Normal levels = 5 mmol/l
Untreated = 10-30 mmol/l
Two types of diabetes.
Type 1 diabetes
Type 1 diabetes usually occurs in childhood. A person with type 1 diabetes is unable to produce insulin and can be treated with regular doses of insulin.
