Atheroma, thrombosis and infarction Flashcards
Thrombosis definition
A solid mass of blood constituents formed within an intact vascular system during life
Embolus definition
A mass of material in the vascular system able to become lodged within a vessel and block it
Ischaemia definition
A reduction in blood flow
Infarction definition
Reduction in blood flow with subsequent death of cells
Reperfusion injury definition
Tissue damage caused when blood supply returns to tissue after a period of ischaemia
End artery supply definition
Only one artery into a certain organ
Atherosclerosis definition
A disease of the arteries characterised by the deposition of fatty material on their inner walls and forming yellow plaques
What do platelets contain?
- Alpha granules - Involved in platelet adhesion to damaged vessel walls. Substances include fibrinogen, fibronectin and platelet growth factor
- Dense granules - Contain substances like ADP which cause aggregation
What is the difference between a thrombus and a clot?
A clot is coagulated blood outside of the vascular system if the vessel has been cut, or after death. A thrombus is the solidification of blood contents within the vascular system during life, often when there is endothelial damage but the vessel is intact.
How does a thrombus form?
- Platelets are activated
- Platelets release chemicals causing aggregation and initiate the clotting cascade (+ve feedback loops)
- Formation of fibrin mesh which traps RBCs
What is Virchow’s Triad?
The 3 things which predispose to thrombus formation:
- Changes in the vessel wall
- Changes in blood flow
- Changes in blood constituents
Give 4 potential events after thrombosis
- Lysis and resolution of the thrombus but with potential organ damage
- Organisation and repair of scar tissue
- Recanalisation with capillaries growing through
- Embolisation
Give 4 ways to prevent a thrombus forming
- Exercise/movement
- Elastic stockings/DVT stockings
- Aspirin
- Warfarin in severe cases
What effects can venous emboli have?
Form pulmonary embolisms:
- Smaller emboli may accumulate to cause idiopathic pulmonary hypertension
- Slightly larger emboli may cause acute respiratory and cardiac problems
- Massive emboli result in sudden death
What effects can arterial emboli have?
- Can travel to the brain causing a cerebral infarct (stroke)
- Can travel to the kidneys causing a renal infarct
- Can travel to the gut causing ischaemic bowel
- Can travel to the foot causing ischaemic foot (dry gangrene)