Circulation Flashcards
What is haemostasis?
The stopping of bleeding.
When does physiological thrombosis often occur?
After a trauma (cut/injury).
What is important for physiological thrombosis?
Vessel wall structure and integrity.
What does a cross section of an artery contain?
Inner lumen with endothelial cells- these make a basal lamina to sit on. Around basal lamina are the SMC surrounded by the interstitial collagen fibres. The lumen contains RBC, WBC, platelets and plasma.
What does the lumen contain?
RBC, WBC, platelets and plasma.
What does plasma consist of?
Water, other molecules and proteins.
What factors does plasma contain?
Clotting factors.
What is serum?
Plasma without clotting factors.
Where are clotting factors produced?
Liver but some in epithelial cells.
How are clotting factors often named?
Roman numerals.
How do clotting factors work and what do they result in?
They are an amplification system resulting in the production of thrombin.
What does thrombin do?
Promotes the conversion of soluble fibrinogen into insoluble fibrin.
What does fibrin form?
A fibrin meshwork of strands.
What is the precursor of thrombin?
Prothrombin- activated by clotting factor amplification system.
What is the clotting factor amplification cascade stimulated by?
Initial trauma.
What does initial trauma result in?
Exposure of interstitial collagens to plasma.
Exposure of a molecule called tissue factor (TF).
What happens to the vessel after trauma?
Blood leaks out of the trauma defect and comes into contact with the interstitial collagen fibres. Plasma clotting factors can then be activated because they are in contact with interstitial collagens. Tissue factor is also released from SMC- TF can now bind a particular clotting factor and activate the amplification cascade.
What does plasma have to do to activate clotting factors?
Contact interstitial collagens.
Where is tissue factor released from?
Smooth muscle cells.
What does tissue factor do?
Binds a particular clotting factor to activate amplification cascade.
How are clotting factors activated in terms of structure?
Many are serine proteases- this means they have a serine amino acid in them and they cleave other clotting factors to form the active molecule.
What does the clotting cascade lead to?
The conversion of prothrombin to active thrombin which stimulates the conversion of soluble fibrinogen into insoluble fibrin.
What is the end-point of the clotting cascade?
The production of insoluble fibrin strands which form a meshwork.
Where are platelets produced?
Bone marrow.