Haemorrhagic Disorders:

Abd El Moaty Soliman El Boray

The platelets is concentrated in the spleen(third),its life span (9-12) days, it is cleared from circulation byR.E.S. platelets functions are adhesion, contraction,secretionand aggregating agents (collagen, Thrombin,Sevotinin andadvenaline). Haemostasis involves vasoconstriction of bloodvessels then platelets form a plug and coagulation factorsforming a fibrin clot (from Factor 1 - Factor XIII).The fibrinogen group includes (Factors I, V, VII, XII), butprothrombin group includes (Factors II, VII, IX, X) are dependenton vit.k and formed in the liver.So abnormal bleedingoccurs in hepatic dysfunction. Prothrombin changed to thrombinwhich is essential to form fibrin present in plasma.Examples of inherited haemostatic defects are (TrueHaemophilia , vascular Haemophilia , Christmas disease) theretreatment by fresh blood or plasma.Examples of acquired haemostatic defects are hypoprothrombinaemiawhich is treated by vit.k. Hypofibrinogenaemia treatedby giving fibrinogen and plasma purpura treated by corticosteroidsand splenectomy. In scurvy vit.c is essential.Laboratory tests used in haemostasis are(C.T.) plasma clottime, PTT, prothrombin time, thrombin time) (B.T., plateletcount , clot retraction , platelet aggregation , plateletadhesiveness).