HTHSCI 1H06 Lecture Notes - Lecture 7: Prothrombinase, Vasospasm, Thromboxane A2
24 Feb 2016
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Document Summary
Explain 3 mechanisms that reduce blood loss. Describe key features and functions of the lymphatic system. Hemostasis is not to be confused with homeostasis- although it does maintain homoeostasis. Hemostasis is a sequence of responses that stops bleeding- it is quick, localized and controlled. Prevents hemorrhage (loss of a large amount of blood) which mostly occurs in smaller blood vessels. Medical intervention is usually required for hemorrhage of larger vessels. Also start as a pluripotent stem cell differentiating into a myeloid stem cell. The myeloid stem cell differentiates into a megakaryoblast, which forms a megakaryocyte and eventually a platelet. Platelets are disc-shaped, are very small (2-4 microns), they contain no nucleus and have a short life span (5-9 days). Stop blood loss from damaged blood vessels by forming a platelet plug. They release chemicals that promote blood clotting and vascular spasm. When there is a damaged endothelium (due to turbulence in blood flow, development of plaque, etc.
