HSS 3305 Lecture Notes - Lecture 9: Von Willebrand Disease, Von Willebrand Factor, Tissue Plasminogen Activator
23 Feb 2016
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Class 9: abnormalities in blood coagulation and hematopoietic system. Arrest of bleeding caused by activation of the blood coagulation mechanism. Adequate amounts of calcium ions in the blood. Small vessels are first line of defense in the body. Constrict on injury to facilitate closure by a clot. Exposure of underlying connective tissue of the endothelium activates coagulation mechanism. Adequate number of platelets to accumulate and adhere to injury area. Platelets: small fragments of cytoplasm from large precursor cells called megakaryocytes. Average survival in the circulation is 10 days, removed by macrophages spleen. Liberate vasoconstrictors and compounds causing platelets to aggregate. Phase 1: formation of thromboplastin by either interaction of. Intrinsic factors in blood (platelets and plasma factors) After thromboplastin interacts with other substances to form prothrombin activator. Phase 3: conversion of fibrinogen into fibrin by thrombin. Thrombin splits off a part of the fibrinogen forms smaller molecules, fibrin monomers.
