PLATELETS AND COAGULATION

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Bio Med and Pathology Mind Map on PLATELETS AND COAGULATION, created by aahughes on 12/04/2013.
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Mind Map by aahughes, updated more than 1 year ago
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PLATELETS AND COAGULATION
  1. THROMBOCYTES
    1. Shed from bone marrow bound cells called MEGAKARYOCYTES
      1. 250,000,000 ARE PRESENT IN EACH ML OF BLOOD
        1. Remain functional for 10 days and are then removed by macrophages
          1. removed in the spleen or liver
    2. STORAGE - In blood filled spaces in the spleen
      1. can be released into the bloodstream by SPLENIC CONTRACTION
        1. Contain high amounts of ACTIN and MYOSIN
          1. Important in homeostasis
      2. VASOCONSTRICTION
        1. A cut vessel immediately constricts reducing blood flow
          1. Release of THROMBOXANES
            1. PLATELETS become 'sticky' and stick to vessel wall
              1. They release SERETONIN which constricts the vessel wall
        2. PLUG FORMATION
          1. Platelets attach to the exposed collagen and each other
            1. ADENOSINE DIPHOSPHATE causes site to become sticky
              1. Platelets build up by a 'positive feedback' system
                1. This is a TEMPORARY seal
          2. COAGULATION (CLOTTING)
            1. Transformation of blood from a liquid to a solid gel
              1. Coagulation is the bodies haemostatic mechanism
            2. The ultimate in clot formation is the conversion of
              1. FIBRINOGEN(PLASMA PROTEIN) TO FIBIRN
                1. Catalysed by the enzyme THROMBIN
                  1. Forms a 'mesh' like structure over wound site
              2. CLOTTING CASCASDE
                1. INTRINSIC PATHWAY - SLOW 10MINS
                  1. Set off with when factor XII(/Hageman) comes into contact with collagen
                    1. Ca2 and platelet factor 3 are required as co-factors in the cascade
                  2. EXTRINSIC PATHWAY - FAST 10SECS
                    1. Requires tissue THROMBOPLASTIN
                      1. which activates FACTOR X, by passing all steps in intrinsic
                        1. Ca2+ and Factor 3 are required
                  3. Clot formation takes 3-6 mins
                    1. Its a temporary solution
                      1. The next step is FIBRINOLYSIS
                    2. FIBRINOLYSIS -BREAKDOWN OF THE CLOT
                      1. An INACTIVE form of PLASMINOGEN is present in the clot
                        1. Its activated to become PLASMIN (activated by FACTOR X)
                          1. Dissolves the clot and fibrin
                            1. Phagocytic WBC's remove debris
                      2. VIT K required by liver
                        1. to synthesise clotting factors
                        2. THROMBOCYTOPENIA
                          1. Low levels of platelets
                          2. HAEMOPHILIA - Absence of FACTOR VII - GENTIC
                            1. INR
                              1. PROTHROMBIN TIME
                                1. Number of secs blood takes to clot
                                  1. OA - Warfarin
                                    1. Ideal INR - 2/3
                                      1. Warfarin synthesises clot factors
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