HTHSCI 1H06 Lecture Notes - Lecture 8: Blood Vessel, Hemostasis, Myeloid Tissue

• School: McMaster University
• Department: Health Sciences
• Course: HTHSCI 1H06
• Professor: Peter Helli

Document Summary

Not the same as homeostasis, but it does maintain homeostasis. It involves the sequencing of events that stops bleeding; it is quick, localized, and controlled. Prevents hemorrhage (loss of a large amount of blood) from smaller blood vessels: medical intervention usually is required for hemorrhages that occur in larger vessels. Vascular spasm/vasoconstriction: a smooth muscle reflex to decrease blood flow to the injured region. Platelet plug formation: adhesion, release reaction and aggregation. Pluripotent stem cell -> myeloid stem cell -> megakaryoblast -> Disc shaped, 2-4micron cell fragment, no nucleus, and short life span (5-9 days) Stop blood loss from damaged blood vessels: form a platelet plug, release chemicals that promote blood clotting and vascular spasm. Platelet adhesion damaged endothelial cells reveal the underlying collagen fibres that platelets stick to. Platelet release reaction liberated adp (sticky landing spot), serotonin, and thromboxane a2 causes vasoconstriction to decrease blood flow to area. Platelet aggregation platelets gather and plug up the hole.