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