- Artery walls have several layers.
- Endothelium (inner lining) smooth, unbroken.
- Damage occurs to endothelium, there's a inflammatory response, white blood cells move in.
- White blood cells form lipids clump together forming fatty streaks.
- More white blood cells, lipids and connective tissue, froming a fibrous plaque (atheroma).
- Plaque partially blocks lumen of artery restricting blood flow, blood pressure increases.
- Arteries harden (atherosclerosis).
Atheromas (increase risk):
- Atheromas develop in artery wall.
- Atheromas can rupture endothelium damaging it, leaves rough surface.
- Triggers thrombosis (blood clot at site of rupture).
- Blood flow to tissues severly restricted, less oxygen.
- Three types of cardiovascular disease - heart attack, stroke & dep vein thrombosis.
How they form: Thrombosis used to prevent extreme blood loss when vessel is damaged. Series of reactions occur leading to blood clot (thrombus):
- Thromboplastin protein released from damaged blood vessel.
- Triggers conversion of prothrombin (soluble protein) into thrombin (enzyme).
- Throbin catalyses conversion of fibrinogen (soluble protein) to fibrin (insoluble fibres).
- Fibrin fibres tangle together, form mesh which platlets (small fragments of blood) red blood cells get trapped - forms blood clot.
Cause heart attack:
- Heart muscle supplied with blood by coronary artery.
- Blood carries oxygen, cells carry out respiration.
- Artery becomes completely blocked by blood clot, no oxygen recieved.
- Causes myocardinal infarction (heart attack).
- Damage/death to heart muscle.
- Symptoms: pain, shortness of breath, sweating.
- Large areas of heart effected, fatal heart failure/death.
- Rapid loss of brain function due to disruption of blood supply to brain.
- Caused (mostly) by blood clot in artery, reducing oxygen.
Deep vein thrombosis (DVT):
- Blood clot in vein, usually leg veins.
- Caused (sometimes) prolonged inactivity; eg. long flights.
- Risk increases with age.
Coronary Heart Disease (CVD):
- Coronary arteries blocked by atheromas, increases risk of blood clots, increasing risk of myocardinal infarction.