PHGY 209 Lecture Notes - Lecture 20: Blood Vessel, Prothrombinase, Phospholipid
30 Oct 2016
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Document Summary
Clot formation is a function of plasma: rbc are innocent bystanders not necessary for the process. Clotting: initiated by injury to blood vessel wall, sequential activation and interaction of a group of plasma protein/ clotting factors. Some enzymes, some co-factors: in the presence of ca++ and some phospholipid agents. Stages to clotting: protein factors named by roman numerals in order of discovery, fibrinogen turn to fibrin via thrombin. Thrombin also consolidates fibrin network: prothrombin turn to thrombin via ca++ in presence of prothrombinase, 2 pathways. Slow (3-6mins: can produce larger amounts however. All required substances already in the blood stream. Much more rapid ( 15-20 secs: through small amounts it can activate the intrinsic pathway to produce more through intrinsic stream. Tissue factors (prot & phospholipid) released from damaged cells. React with plasma protein to produce prothrombinase. Thrombin activates both intrinsic and extrinsic pathways. Clotting is kept in check by: inhibitors.
