Atherosclerosis + blood clotting and risk factors Flashcards
(15 cards)
What is atherosclerosis
-Atherosclerosis is where atheromas (fatty deposits) build up in the walls or arteries, leading to the hardening and narrowing of arteries
Process of atherosclerosis
-Atherosclerosis occurs when the endothelial lining of an artery becomes damaged; this can be because of high blood pressure, age or smoking habits
-This damage triggers an inflammatory response, leading to the accumulation of white blood cells in the artery wall
-Cholesterol also builds up and this forms the atheroma
-Calcium salts and fibers build up and hardens the atheroma, forming a plaque which narrows the lumen of the artery
-This narrowing of the lumen obstructs the flow of blood, increasing the blood pressure
-This is an example of a positive feedback mechanism
Consequences of atherosclerosis
-Increased risk of coronary heart disease
-Increase risk of strokes
-Increased risk of myocardial infarctions
-Increased risk of thrombosis (blood clot formation)
Positive feedback loop definition
-A positive feedback loop is a process in which a change in a system causes a response which amplifies or increases the original change
Blood clotting Process
-Damage to the blood vessel exposes collagen fibers in the blood vessel wall
-Platelets (now activated) stick to the exposed area and to each other, forming a temporary platelet plug
-They release chemicals like thromboplastin
-Thromboplastin and calcium ions catalyse the conversion of the inactive protein prothrombin to the active thrombin
-This thrombin (enzyme) then converts the soluble fibrinogen to the insoluble fibrin
-The fibrin forms a mesh that traps red blood cells and platelets, forming a blood clot over the wound
-The activated platelets also release the chemical serotonin, which causes the smooth muscle in the walls of the blood vessel to contract and the lumen to narrow, further reducing the blood flow to the damaged area
-The body can now repair the blood vessel
Why is blood clotting important
-Seals the wound
-Prevents excessive bleeding
-Minimises the risk of infection
Blood clotting link to atherosclerosis
-Atherosclerosis causes high blood pressure
-This can cause damage to the endothelial layer, which triggers the clotting response
-A thrombus can form which further obstructs blood flow and increases blood pressure
Why is a thrombus formed dangerous
-A thrombus can completely block an artery, leading to reduced or no blood flow
-If the coronary artery is blocked, this can lead to a myocardial infarction
-The thrombus can also break off and travel, leading to an embolism somewhere else e.g brain or lungs
-If the clot reaches the brain , a stroke can occur
-Deep vein thrombosis or pulmonary embolisms can also occur
Risk Factors of CVD (and strokes)
Diet rich in saturated fats (risk factor)
-A diet rich in saturated fats can increase blood cholesterol levels
-This increased the risk of atheroma formation
-This increases the risk of blood clots
-This increases the risk of hear attacks or strokes
Salt heavy diet (risk factor)
-A salt heavy diet can increase the risk of high blood pressure
-This can cause damage to the endothelial lining of blood vessel walls, leading to an atheroma forming
-This atheroma increases the risk of blood clots being formed, which obstruct the flow of blood and can increase the risk of heart attacks and strokes as well us pulmonary embolisms and deep vein thrombosis
Factors affecting high blood pressure
-Age
-Diet
-Stress
-Excessive alcohol consumption
Smoking (risk factor)
-Cigarettes contain carbon monoxide, which binds to haemoglobin in the blood, reducing the amount of oxygen transported around the body, this also reduces the amount of oxygen being absorbed into body tissues:
-Low levels of oxygen in the heart can cause a myocardial infarction
-Low levels of oxygen in the brain can cause a stroke
-Cigarettes also contain nicotine, this causes platelets to become more sticky, increasing the risk of blood clots forming and therefore increasing the risk of CVD
Other risk factors ( inactivity, age, genetics, gender)
Inactivity- Increases blood pressure
-Genetics: particular allelles can increase the risk of high blood pressure or higher blood cholesterol levels
-Age: plaque builds up slowly over time
-Gender: Men are 3x more likely to develop cardiovascular disease than pre- menopause women; this is because oestrogen increases the levels of high-density lipoproteins, which helps to remove excess cholesterol from arteries. Men have less oestrogen than women
Correlation vs causation
Correlation between two variables does not always infer that there is a causal relationship between the two variables
