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Details Title: blood Description: physiology 2007 Total Flash Cards: 5 Created: 12/13/2007 17:16:19	To study from this set of flash cards, or to create your own your own study flash cards, register HERE. If you are already a registered user, CLICK HERE.
Cards Term Phases of homeostasis Definition Vascular Spasms Platelet Plug Formation Coagulation (Has three phases) Term Vascular Spasms   Phase 1 of Hemostasis  Definition -Immiediate response to blood vessel injury is constriction of blood vessel.    -Triggered by direct injury to vascular smooth muscle (chemicals released by endothelial cells and platelets, and reflexes intitiated by local pain receptors.    -A strongly constricted artery can reduce blood loss for 20-30 minutes, allowing platelet plug formation and clotting to occur.   Term Platelet Plug Formation   Phase 2 of Hemostasis  Definition -Platelets form plug which temporarily seals break.    -When endotheliem is damaged and underlying collagen fibers are exposed, platelets:     - swell and form spiked processes     -become sticky and adhere to exposed collagen.     -once attached, platelets degranulate and release chemicals: 1.Serotonin- enhances vascular spasms 2. ADP- Attracks more platelets 3. Thromboxane A2- Stimulates both of above.   -Positive feedback cycle which attracks and activates a greater and greater # of platelets.   -Within 1 min. a plug is formed which further reduces blood loss.   Term Coagulation   Phase three of Hemostasis   Definition -Blood is transformed from a liquid to a gel.   -It is considered a complicated process which involves  over 30 different factors.   -Factors which enhance clotting: coagulation or procoagulants   -Factors which inhibit coagulation: anticoagulants.   -Clotting may be initiated by intrinsic or extrinsic pathways (Both pathways require ionic calcium and involve activation of a series of procoagulants, each functioning as an enzymeto activate the next proagulant in the sequence)    -Inside the body both pathways are usually triggered by the same tissue damaging events.    -Outside the body (testtube) clotting is only initiated by the intrinsic pathway.   Term Definition