Term
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Definition
| The process of causing bleeding to stop, particularly within a damaged vessel, eventually forms hemostatic plug. |
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Term
| Major components of hemostasis |
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Definition
Coagulation factors I-XIII
von Willebrand factor
Platelets
Vessel wall |
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Term
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Definition
| Membrane phospholipids with ATP, ADP, calcium, and platelet factor 4. |
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Term
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Definition
| Involves platelets clotting over site of injury. |
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Term
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Definition
| Coagulation factors form cross linked fibrin over wound. |
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Term
| Sequence of primary hemostasis events after vessel injury |
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Definition
1. Reflex vasoconstriction occurs to limit blood loss.
2. If flow is slow (small wound), then platelets attach to collagen via GPIa. If flow is fast, then platelets transiently attach to vWF via GPIb, vWF binds to collagen.
3. Fibrinogen binds to platelets via GPIIb/GPIIIa
4. Activated platelets secrete ADP, TXa2, and Ca. Also aggregate over wound. Activated platelets attached to each other via fibrinogen bound to GPIIb/GPIIIa. |
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Term
| Sequence of secondary hemostasis events after vessel injury |
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Definition
1. After platelet formation, phospholipid complex expression leads to Thrombin production.
2. Thrombin converts fibrinogen inside the clot into cross linked fibrin. |
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Term
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Definition
1. After wound is repaired, the fibrin clot is no longer needed. Endothelial cells express tPA, which converts plasminogen to plasmin when acting in cooperation with urokinase.
2. Plasmin breaks up clot.
3. Breakdown products are D dimer (cross linked fibrin), FDP (from non cross linked fibrin, and FgDP (from fibrinogen). |
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Term
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Definition
| Need to be able to draw out. |
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Term
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Definition
| Also known as fibrinogen. Converted to non cross linked fibrin by thrombin. |
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Term
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Definition
| Prothrombin, converted to thrombin by factor Xa |
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Term
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Definition
| Also known as tissue factor, combines with factor VIIa to form extrinsic Xase. |
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Term
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Definition
| Also known as Proaccelerin, activated by thrombin, engages in feedback loop to produce more thrombin. |
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Term
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Definition
| Calcium ion, used in converting factor IX to factor IXa. |
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Term
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Definition
| Also known Proconvertin, starts extrinsic pathway. |
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Term
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Definition
| Also known as antihemophilic factor, activated by thrombin as part of intrinsic pathway. Activates factor Xa |
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Term
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Definition
| Also known as Christmas factor, starts of intrinsic cascade. Activated by factors VIIa, Ca, and XIa, activates Xa. |
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Term
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Definition
| Plasma thromboplastin antecedant, activated by thrombin, activates IXa. |
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Term
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Definition
| Hageman factor, activates XIa. Tested for in PTT test. |
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Term
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Definition
| Fibrin stabilizing factor, activated by thrombin, forms cross links on fibrin. |
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Term
| Location of tissue factor |
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Definition
| Not circulating in bloodstrean, found on monocytes and macrophages. |
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Term
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Definition
1. Prothrombin time (PT)
2. Activated partial thromboplastin time (PTT) |
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Term
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Definition
Tests extrinsic pathway, starts from factor VII.
Measures clotting time of plasma after addition of thromboplastin (has tissue factor and lipids) and calcium.
End point is non-cross linked fibrin formation. |
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Term
| International Normalized Ratio (INR) |
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Definition
Designed to monitor patients using warfarin: patients differ in sensitivity toward factors II, VII, and X. PT from one lab may not be comparable to another lab's results.
INR= (PT of patient/ PT of control)^ISI
ISI=International Sensitivity Index (WHO standard=1) |
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Term
| Activated Partial Thromboplastin Time (PTT) |
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Definition
Tests intrinsic pathway, starts from Factor XII activation. Measure clotting time after addition of factor XII activator, phospholipid, and calcium
End point is non-cross linked fibrin.
Normal range: 24-33.8 sec. |
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Term
| Tissue Factor Pathway Inhibitor (TFPI) |
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Definition
| Inhibits TF-VIIa complex from activating extrinsic pathway (Xa and IXa activation). |
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Term
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Definition
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Term
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Definition
Makes complex with antithrombin (AT, negatively charged Heparin with positively charged AT) to inhibit thrombin and factor Xa.
Half life= 90 min
Monitored by PTT.
Neutralized by protamine |
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Term
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Definition
Inhibits Vitamin K synthesis, which affects factors II, VII, IX, and X.
Protein C and S also inhibited.
Monitored by PT INR, usual target for thrombosis is 2.0-3.0 |
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