Zusammenfassung der Ressource
Haemostasis
- 1.) Vascular Spasm
- Narrowing of blood vessel
- 2.) Platelet Plugging
- Platelets (thrombocytes)
- Platelets stem from Myeloid stem cells
- Break off from Megakaryocytes (from Myeloid)
- Blood-bourne, contain organelles and enzymes. No nuclear material
- Stick to loose Collagen
- Release ADP (adenosine diphosphate)
- AND Thromboxane A2 (TxA2)
- This increases stickiness
- In undamaged vessels Prostacyclin inhibits
- 3.) Clotting/Coagulation
- Intrinsic Pathway
- Problems inside
- Starts with Factor XII (Hageman Factor)
- Activates to Factor XIIa
- Cascades down to
- Factor X Now needs Ca+ to activate X
- Common Pathway
- Factor Xa
- Prothrombin
- Enzyme Prothrombinase. Needs Ca+
- Thrombin
- Activates FVIII
- Factor VIII Stabalises clot
- Extrinsic Pathway
- Outside tissue injury
- Thromboplastin (Platelet Tissue Factor III)
- Thromboplastin activates Factor XII
- Released in very high concerntrations
- Results in instant course to comman pathway
- Factor X
- Factor VIIa
- Releases Thromboplastin
- Plasma proteins (Factors) some made in liver with Vit K
- Both pathways need Ca+ to activate
- Fibrinogen made in Liver
- Thrombin breaks down Fibrinogen
- Fibrin Factor I
- AND
- Warfrin mimics Vit K (stops clotting factors)
- Clot Removel
- Plasminogen
- Breaks down into Plasmin
- Ptoteolytic Enzyme
- Breaks down Fibrin
- Called Fibinolysis
- Plasma protein