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Hemostasis Platelet Plug Formation Vascular Spasms Coagulation

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Hemostasis Platelet Plug Formation Vascular Spasms Coagulation 10/20/2015 DO NOT COPY! THIS IS FOR REFERENCE ONLY!!! Receiver Hemostasis Type A, Type A, Type B, Type B, Type AB, Type AB, Type O, Type O, Rh- Rh+ Rh- Rh+ Rh- Rh+ Rh- Rh+ Stoppage of blood flow Type A, Rh- Y Y N N Y Y N N Type A, Result of a break in a blood vessel Rh+ N Y N N N Y N N Type B, Hemostasis involves three phases Rh- N N Y Y Y Y N N Type B, Platelet plug formation Rh+ N N N Y N Y N N Donor Type Vascular spasms AB, Rh- N N N N Y Y N N Type Coagulation AB, Rh+ N N N N N Y N N Type O, Rh- Y Y Y Y Y Y Y Y Type O, Rh+ N Y N Y N Y N Y Platelets Platelet Plug Formation •(Thrombocytes) Collagen fibers are exposed by a break in a •Fragments of megakaryocytes in bone blood vessel marrow •Attracted to hemorrhage Platelets respond by becoming “sticky” • Plugs leaks and cling to collagen fibers • Promotes constriction of blood vessel Anchored platelets release chemicals to • Triggers inflammation attract more platelets • Initiates clotting reaction Platelets pile up to form a platelet plug http://www.sacs.ucsf.edu/home/cooper/Anat118/BloodCells/blood98/default.htm#Blood- Neutrophils Vascular Spasms Coagulation Anchored platelets release serotonin Injured tissues release thromboplastin Thromboplastin, other blood protein clotting factors, Serotonin causes blood vessel muscles to and calcium ions to form a prothrombin activator spasm (constrict) Prothrombin activator triggers a clotting cascade Spasms narrow the blood vessel, decreasing The amount of prothrombin activator in the blood blood loss is increases proportionally as damage increases 1 10/20/2015 Clotting Cascade Blood Clotting Fibrin threads: Prothrombin activator converts prothrombin The threads stick to damaged tissue, trapping RBCs to thrombin & platelets Prothrombin is a protein always present in This forms the clot plasma Once a clot begins to form, it promotes additional Thrombin is an enzyme clotting Thrombin will act upon other clotting factors other Thrombin catalyzes a reaction in which than fibrinogen, causing more prothrombin to fibrinogen proteins are joined together into form thrombin thread-like fibrin Positive-feedback mechanism Unstable & short-lived Blood Clotting Undesirable Clotting Fibroblasts will invade the clot and produce fibrous connective tissue, then fix damaged Thrombus endothelium A clot in an unbroken blood vessel This reinforces the clot Coronary thrombosis Eventually, the clot retracts, releasing serum and drawing the edges of the damaged tissue together Clots in vessels that serve the heart Plasminogen will be converted to plasmin Cranial thrombosis The enzyme Plasmin breaks down fibrin and other clot associating proteins Clots in vessels that serve the brain Undesirable Clotting Undesirable Clotting Embolus Infarction A clot that breaks away and floats freely in the When a clot blocks a vessel to the point where blood stream the tissue served by the vessel dies Keep moving until they reach narrow vessels Myocardial infarction where they may become lodged & block blood flow Heart attack Embolism Clots in vessels that serve the heart Upsets normal heart function 2 10/20/2015 Bleeding Disorders Developmental Aspects of Blood Thrombocytopenia Sites of blood cell formation Platelet deficiency The fetal liver and spleen are early sites of Even normal movements can cause blood cell formation bleeding from small blood vessels that Bone marrow takes over hematopoiesis by require platelets for clotting the seventh month Hemophilia Fetal hemoglobin differs from Hereditary bleeding disorder hemoglobin produced after birth Normal clotting factors are missing 3.
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