what is Haemostatsis
Haemostasis is a balance between prevention of excessive bleeding while avoiding too much bloodclotting/thrombosis.
Where is most of the blood in the Haemostatsis
Most of the blood is in the vascular system the blood vessels
What the parts of Haemostatsis?
- Vascular system
2.Circulating platelets
3.Coagulation factors
What are the two main elements of Haemostasis
Platelets and coagulation factors with their final products, platelet plugand fibrin mesh
What happens in the vasoplasm
Cells in the area signal the epithelia cells to secrete endothelia so it binds to the receptor under the smooth muscle activating an intracellular mechanism curing contractions
Where is the platelets made and how long does it live for
- Produced in the bone marrow from megakaryocytes
- Live for a week
- Have no DNA
How does it go from megakaryocytes to platelets and what happens if there is too many or too little
- In the bone marrow megakaryocytes release platelets into sinusoidal blood vessels
2.Too many platelets lead to clotting and death
Not enough - bleeding in the brain and die
We need a certain amount
What happens in the Platelets plug formation?
- endoepithial cells produce vonwilebrand which the GP1B protein binds to and also the platelets bind
- the platelets release ADP and serotonin which will increase the vasospasm and tell more platelets to come which is platelet aggreation
3.Platelets to go injured area it can’t go to healthy place sue to the release of nitric oxide
What happens in coagulation?
- Strengths the plug by making a mesh to seal damaged area
What is the structure of the platelets?
- Glycogen
- Lyosomes
- Mitochondrion
- Plasma membrane
- Dense granule electron-have some small molecules like ADP and calcium,
- Alpha granule-have lots of different proteins
What are the other functions of platelets?
- Repair and tissue healing
2.Can be injected to hair for hair growth transplant however using other platelets requires that right blood type
What is coagulation cascade?
A series of enzymatic reactions which act one upon another in a sequence
What does Fibrinolysis do?
Breaks down fibrin clot to return to normal state
What is enzyme cascade?
1.Plasminogen is activated generating key enzyme plasmin
2.Plasmin dissolves fibrin clots into soluble fragments including D-dimer
3.Binding of plasmin to fibrin localises fibrinolysis to clot itself -dissolves blood
Why thrombosis is so important?
Can cause of most cases of heart attack and strokes
what is another reason thrombosis occur?
Abnormalities of the vessel wall such as inflammation and direct injury
What is the cause of thrombosis?
1.Abnormalities of blood flow (deep veins)
2. smoking and post-part
What is Embolism
Embolism is the blockage of a blood vessel
what is Extrinsic (Tissue Factor) pathway
extrinsic due to external addition of thromboplastin
2. Tissue factors activates FVII when ca is there leading to generation of factor xa
What is Intrinsic pathway
Intrinsic pathway is initiated by contact activation with a foreign surface: glass, kaolin
