Atheroma, Thrombosis and Ebolism Flashcards
What is atherosclerosis?
Degeneration of arterial wall characterised by fibrosis, lipid deposition and inflammation.
-limits blood circulation and predisposes thrombosis.
What are the commonly affected vessels of atherosclerosis?
- Bifurcations
- Abdominal aorta
- Coronary arteries
- Popliteal arteries
- Carotid vessels
- Circle of Willis
What are the non-modifiable risk factors of atherosclerosis? (4)
- Age
- Male
- FH
- Genetic
What are the modifiable risk factors of atherosclerosis? (5)
- Hyperlipidaemia
- Hypertension
- Smoking
- Diabetes
- CRP
Why does atherosclerosis arise?
Due to chronic injury and repair of the endothelium.
-1st step = endothelial injury
What are the main causes of atherosclerosis? (4)
- Haemodynamic injury
- Chemicals
- Immune complex deposition
- Irradiation
Describe the process of atheroma formation.
- Hyperlipidaemia and endothelial injury»_space; lipid accumulation in intima
- Monocytes ingest the lipid»_space; foams cells (fatty streak)
- Foam cells secrete chemokines»_space; attract more monocytes/lymphocytes/smooth muscles cells
- Forms ATHEROSCLEROTIC PLAQUE
What is the structure of an atheromatous plaque?
- Fibrous cap (superficially)
- Necrotic centre
- Media (deep)
What is the fibrous cap of an atheromatous plaque composed of? (4)
- Smooth muscle cells
- Macrophages
- Foam cells
- Collagen
What is the necrotic centre of an atheromatous plaque composed of? (4)
- Cell debris
- Cholesterol
- Foam cells
- Calcium
What is thrombosis?
Solidification of blood contents in the vessel during life.
How is thrombosis different to a clot? (3)
- Thrombosis is during life, clot is stagnant blood
- Thrombosis is dependent on platelets, clots are enzymatic processes
- Thrombosis is firm, clots are elastic/adopt shape of the vessel
What are platelets?
Fragments of megakaryocytes in the bone marrow.
-circulate in the blood and help form clots
How are platelets activated?
They bind to collagen exposed by endothelial damage»_space; activation.
What do activated platelets secrete? (2)
- Alpha granules; fibrinogen, fibronectin, PDGF
- Dense granules; chemotactic chemicals
What is Virchow’s triad?
The 3 factors required for thrombosis;
- intimal surface of vessel
- blood flow (stasis/turbulence)
- blood constituents (mediators)
How does an arterial thrombus form?
-Turbulence >> loss of endothelial cells >> exposure of collagen >> platelet adherence and activation >> THROMBUS FORMATION
What are the lines of Zahn?
Rib-like markings characteristic of thrombi near the heart or aorta.
What factors contribute to venous thrombosis? (3)
- Intimal changes; valves
- Change in blood flow; immobile
- Change in blood constituents; mediators/FV leiden/oestrogen
What are cardiac thrombi known as?
Mural thrombi.
-occur over areas of endomyocardial injury
What are the main causes of cardiac thrombi? (4)
- MI
- Myocarditis
- Arrhythmias
- Cardiomyopathy
What is the general sequence of embolism formation?
Occlusion of vessel (thrombus) >> resolution >> incorporation into vessel wall >> recanalisation >> embolisation
What is an embolus?
A mass of material in the vascular system able to lodge in a vessel and block it.
What are the different types of emboli?
- Exogenous/endogenous
- Solid/liquid/gas
