HUBS192 Lecture Notes - Lecture 21: Hemostasis, Coagulation, Thrombin

• School: University of Otago
• Department: Human Body Systems
• Course: HUBS192
• Professor: Greg Jones

Document Summary

Platelets in tiny corner of the image (very small relative to other blood cell types) The size is between 2-4 micrometres, very small. All cells derived from 1 common progenitor stem cell. Platelets doesn"t derive directly from stem cell; you get the formation of megakaryocyte (huge bundle) Derive from massive blob, megakaryocyte forming in bone marrow; can grow to enormous size. Expands and suddenly ruptures to release tiny little platelets; formation of platelets through rupture of megakaryocytes; releases a whole host of platelets; rapid production/turnover of platelets. This is known as thrombopoiesis; stimulated by thrombopoietin (hormone) Haemostasis (stop bleeding) and blood clotting, part of haemostasis (requires further steps other than aggregation of platelets) Process of haemostasis: involves blood vessels, platelets (pivotal) and blood coagulation system (if bleeding is severe enough) Initiation of stage 1: lead to stopping of bleeding, not clotting; only involves platelets.