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15 Cards in this Set
- Front
- Back
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What is a zymogen and its role in clotting?
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A zymogen is a biologically inactive protein or enzyme that is activated by site-specific or enzyme that is activated by site-specific proteolysis.
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What is factor number for factor XIIIa? And how is it activated?
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Factor XIIIa – transglutaminase Thrombin activates it from Factor XIII
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When the hard clot is formed what forms it?
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hard clot – covalent bonds formed between fibrin subunits – covalent bond formed between NH2 of glutamine and NH3 of lysine and uses factor XIIIa as enzyme
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Describe the post translational modification importance of Prothrombin… and location it occurs and how that relates to cascade activation
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In liver the glutamic acids get modified by Carboxylase (enzyme) which give them an extra COOH, and therefore creating "gamma" carboxy-glutamate opposed to regular glutamate…Prothrombin gets a -2 charge…
When a vessel is damaged it releases a Ca2+ and goes and binds immediately to prothrombin at wound site THUS ACTIVATING CASCADE |
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What is the importance of Vit. K in clotting? What Drugs inhibit the recycling of Vitamin K and what enzyme do they inhibit to do this?
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Vit K allows carboxylase to occur to Glutamate which allows for prothrombin to become thrombin… Warfarin and Dicoumeral competively inhibit the enzyme "Epoxide reductase" so Vit. K can not be re-used
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Clotting cascade occurs in two pathways once of which "intrinsic pathway" means what?
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does not require a protein outside of the vasculature to activate
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Describe why extrinsic pathway mainly differs from intrinsic?
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Differenent starting points and Extrinsic pathway requires an active component that is not part of the vasculature under normal conditions (starts with Tissue Factor III)
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What are the vitamin K dependent factors in the cascade?
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X, IX, VII
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What are the positive feedback factors?
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• Thrombin • FXIa • FXa • FVIIa
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What are the main coagulation tests (reference times)? Explain times for normal and whether it tests intrinsic or extrensic
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Partial Thromboplastin Time (PTT)- times clot from XII to fibrin for intrinsic and common pathways (20-39 sec)- activated by kaolin added to plasma
Prothrombin Time (PT)- times clot from VII to fibrin (extrinsic and common) (30s)- activated by adding TF (tissue throboplastin) |
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For first type of regulation what factor is mostly involved and what does it do?
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Thrombin (FIIa)- cause negative feedback on many things
1. Thrombin binds fibrin – inactivates fibrin 2. FVIIIA to FVIIIi, 3. Xa--> Xi 4. Va-->Vi 5. Thrombin can cut prothrombin to create an inactive irreversible form |
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What is the process of regulation involving Protein C?
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1. Thrombin combines with protein Thrombomodulin to create a TM complex
2. Cuts Protein C into active C-a 3. Protein C-a + other proteins inactivates FVa and FVIIIa – which decreases production of thrombin |
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What do protein C-a's have?
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• Activated Protein C-a’s are decorated with g-carboxyglutamate
- The g-carboxyglutamate are Ca attractors so they will bind to Ca and not allow further cascade to occur |
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What are "anti-clotters" used for stroke victims within a few hours of stroke
What does heparin activate besides being a competitive inhibitor to Vit K recycling? |
1. TPA (tissue plasminogen factor)- precursor to plasmin dissolves clot- fibrinolysis
2. activates antithrombin III- which binds to Xa and thrombin |
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Why would decreases in Ca in body help prevent clots?
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Ca binds to Prothrombin, XIa, and many other agents to allow clotting cascade to occur
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