PHGY 209 Lecture Notes - Lecture 12: Thrombin, Antibody, Thromboxane A2
Document Summary
There are a number of interacting, overlapping mechanisms: vascular response. Blood vessel walls constrict to reduce the flow of blood through the injured area: platelet response. Platelets accumulate at the site of injury, forming a temporary plug: vascular response + platelet response = primary hemostasis. Slows down blood flow to allow clot formation o clot formation. Occurs a bit later: vascular response vasoconstriction constriction occurs at the region where the injury has occurred so blood flow is reduced to a trickle. As the blood vessel wall constricts, the opposed endothelial cells stick together. A clamp-like: nervous reflex, myogenic response: smooth muscle cells in vessel wall respond to injury by contracting. Form a plug called a white thrombus (actual clot is called red thrombus) Platelet production occurs at the same sites as red blood cells, e. g. bone marrow for adults. In contrast to the red blood cell, only the nucleus divides no cytoplasmic division.