PHGY 209 Lecture Notes - Lecture 11: Vitamin K, Vitamin K Deficiency, Antithrombin
16 Sep 2016
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Triggered by collagen exposure then there"s a whole sequence of activation and promotion which involves calcium and plasma factor phospholipids. When blood vessels are damaged, some of the tissues in surrounding areas enter into the blood stream. Tissue factors protein and phospholipid enter into the circulation and interact with another factor in the plasma. Believed that a small amount of thrombin is produced at the beginning . Both pathways interact with each other at many levels. The small amounts of thrombin generated rapidly by the extrinsic scheme, are sufficient to trigger its strongly positive feedback effects on the intrinsic scheme to generate larger quantities of thrombin. Clotting is kept in check by inhibitors (of platelet adhesion) and anticoagulants (naturally occurring chemicals which block one or more of the reactions of the coagulation scheme). Heparin and antithrombin iii work together to block ix, x, xi, xii. Congenital: hereditary deficiencies of (usually) a single factor, e. g. vii (hemophilia)
