Arterial and Venous thrombosis Flashcards
What is the difference between a clot in a living and a dead person + why
Living - one layer
Dead - red cells tend to settle out before clot forms so we have two layers: Lower deep-red and upper clearer with platelets
What does the clot in a dead person take the shape of
The shape of the vessel in which they have formed
How does the clot formed in a dead person break down
Hydrolysis by enzymes released by cells of the vessel wall and RBCs
What is a thrombus
Solidification of blood contents that form within the vascular system during life
What is the role of a platelet
Closing small gaps in vessel walls through trauma
What are platelets derived from
Megakaryocytes
What structures can be found in platelets
- Mitochondria
- Cytoskeleton
- Alpha granules
- Dense granules
What do alpha granules in platelets contain
Fibrinogen, Fibronectin, Platelet growth factor and anti heparin
What are found in dense granules of platelets
ATP and ADP
Role of ATP and ADP in clotting
Platelet aggregation
What is the result of the platelet cascade forming in an intact non-damaged vessel
Thrombus
What three ways can a thrombus form
- Changes in intimal surface of vessel
- Changes in pattern of blood flow
- Changes in blood constituents
What three ways can a thrombus form
- Changes in intimal surface of vessel
- Changes in pattern of blood flow
- Changes in blood constituents
^ Virchow’s triad
How does an atheromatous plaque cause arterial thrombosis
- Plaque enlarges
- Plaque protrudes into lumen
- Disrupts blood flow.
- Causes loss of intimal cells
- Denuded plaque surface is presented to platelets
- Causes fibrin deposition and platelet clumping
- Bare luminal surface of vessel will have exposed collagen and platelets
How does an atheromatous plaque cause arterial thrombosis
- Plaque enlarges
- Plaque protrudes into lumen
- Disrupts blood flow.
- Causes loss of intimal cells
- Denuded plaque surface is presented to platelets
- Causes fibrin deposition and platelet clumping
- Bare luminal surface of vessel will have exposed as endothelial cells lining vessel are damaged to collagen and platelets
What two of the three Virchow’s triad can apply to arterial thrombosis and under what conditions
- 3rd - Plaque is in aorta of the smoker or someone with high cholesterol / LPL as there is a change in blood constituents
(book didn’t mention the other one lol)
Why is arterial thrombosis in the aorta of a smoker / high LPL self-perpetuating
Platelet growth factor contained in alpha granules causes proliferation of arterial smooth muscle cells
What do atheromatous plaque mostly consist of
Arterial smooth muscle cells
What is the first layer of a thrombus made of
Platelets
What is and how does the second layer of a thrombus develop
- Red blood cells
2. Precipitation of fibrin meshwork traps red blood cells above platelet layer
What is the alternating layer of a thrombus called
Lines of Zahn
In which direction will the thrombus grow in
Direction of the blood flow - propagation
Why does an atheroma not occur in veins
Low pressure
How does venous thrombosis occur
- Presence of valves causing disturbances or exposed to trauma
2
How do venous thrombosis occur
- Blood pressure falls during surgery or heart attack slowing blood flow
- Venous return slows down due to lack of calf muscle contractions (DEEP VEIN THROMBOSIS)
What symptoms would I be looking for in people with arterial thrombosis
- Loss of pulse distal to thrombus
2. Signs of impaired blood supply (cold, ,pain and pale in area)