Haemostasis

Haemostasis

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

Next up

Description

Resource summary

Similar

	Created by Caroline Oxford almost 11 years ago