Thombosis and infarction Flashcards
What is a thrombus?
A solid mass of blood constituents formed within an intact vascular system within life
What causes arterial thrombosis?
superimposed on atheroma (as it causes turbulent flow + there is plaque/fibrous cap rupture)
What causes venous thrombosis?
blood stasis (due to surgery, immobilisation, damaged valves)
what type of thrombus is formed in arterial thrombosis?
White thrombus (platelets + fibrin)
What type of thrombus is formed in
Red thrombus (RBCs entrapped in fibrin meshwork)
What are the 3 components of virchow’s triad?
Change in flow, change in vessel wall, change in blood constituents
How do blood cells normally travel through blood vessels?
Laminary flow (through centre)
What is an embolus?
Mass of material in the vascular system able to become lodged within a vessel and block it
What is ischaemia?
Redcuction in arterial blood flow to tissues (therefore they have a low oxygen and nutrient supply)
What is infarction?
Subsequent necrosis of cells caused by ischaemia (Reduction in blood flow)
give examples of organs with a dual blood supply
Liver, brain (some parts), lungs
How does repurfusion injury occur?
Lack of oxygen during ischaemia caused a build up of H+ and Ca2+ in cells (cells become acidic). When the cells are reperfused ROS are formed, Ca2+ causes contraction…
Where are atheromatous plaques found and why?
Systemic arteries + Ao due to the high pressure
Describe the structure of an atherosclerotic plaque
Cholesterol crystals, lipid deposits, foam cells, SM cells, Macrophages, T lymphocytes, fibrous cap
How does an atherosclerotic plaque form?
Damage to endothelial cells (E.g. by free radicals from smoking, HTN [shear force], diabetes, hyperlipidaemia)
Give 5 complications of atheroma
Ischaemia, aneurysm and dissection, carotid artery stenosis (risk of stroke), coronary artery (angina, acute coronary events), gangrene, leg ulcers
What is an atherosclerotic plaque composed of?
Fibrous plaque and necrotic core (w/ cholesterol crystals, lipids, cellular debris…)
What is the fibrous cap composed of?
lipid deposits, foam cells, SM cells, Macrophages, T lymphocytes, colagen
What covers the fibrous cap?
endothelial cells
How does heparin work?
Activates anti-thrombin –> inactivates factor Xa and thrombin (IIa)
How does LMWH work?
Inactivates factor Xa
