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55 Cards in this Set
- Front
- Back
What is the difference between Plasma and Serum?
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-They are both Liquid portions of the blood
-Plasma can clot - Has Clotting factors in it -Serum cannot clot - Clotting factors have been removed |
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What is Hemostasis?
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-Normal protective process that stops a bleed
-Limits Blood Loss -Clot occurs |
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What is Blood Clot in a Blood Vessel called?
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-Thrombus
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What is the process of dissolving a Clot called?
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Fibrinolysis
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Describe the timeline of clotting.
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Occurs very slowly and then an explosive growth (clot) occurs.
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What are the 4 Important event in Clotting?
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-Vasoconstriction
-Platelet Activation/Adhesion/Aggregation -Fibrin Meshwork -Fibrinolysis - Clot Dissolution |
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Where do Platelets come from?
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Broken off of Megakaryocytes
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How do activated Platelets facilitate clotting?
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-They change surface properties of their membrane
-Expose new shit on the membrane -Allows Blood CLotting Factors to Bind |
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Name 2 Potent Activators of Platelets. Which shouldn't be encountered if everything is ok?
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-Collagen - this one
-Thrombin |
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What is Thrombin?
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-Platelet Activator
-Last Serine Protease in the Clotting Cascade |
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Name 2 Secreted Molecules that Activate other Platelets.
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-ADP
-Thromboxane A2 |
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How does Aspirin work?
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-Targets Cyclooxygenase
-First Enzyme in the Prostaglandin Pathway -Would normally lead to formation of Thromboxane A2 -Without Thromboxane A2, can't activate other Platelets -Prevents Clotting |
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What is von WIllebrand Factor? Where is it released? Where is stored?
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-Adhesive Protein that Facilitiates Clotting
-Released at sites of Injury -Stored in Platelets |
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What does VWF bind to? How does it act?
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-Binds to Collagen and Cell Surface Receptors on Platelets
-Allows Platelets to Bind to Collagen and other Platelets |
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What Molecule forms a bridge between activated Platelets?
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Fibrinogen
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What is the Most Common Congenital Bleeding Disorder?
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-von Willebrand Disease
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What happens in von Willebrand Disease?
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-VWF deficiency
-Defective Platelet Adhesion - Can't stick to sites of injury -Diathesis - Abnormal propensity for bleeding |
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Describe, in general, how the Clotting Cascade works.
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-Chain rxn of Enzymes
-2 Subunit Enzymes including a Serine Protease and a Regulatory Subunit or Cofactor -They bind to each other and to Membrane Surface -Protein is Proteolysed to become the next Protease -Chain Reaction |
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Where are most Clotting Factors Synthesized?
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Liver
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What role does Calcium play in clotting?
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Necessary for most steps in the clotting cascade
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What does Tissue Factor do?
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-Triggers the Clotting Cascade
-Binds to Factor 7 and activating it to Factor 7a |
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What is Factor 7a?
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-Activated, Serine Protease Form of Factor 7
-Part of Clotting Cascade -Activated Factors 9 and 10 - Blood Clotting Proteins |
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Where is Tissue Factor found?
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Cell Surface of Tissues
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Where in most Blood Vessels is Tissue Factor very Abundant?
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-Adventitial Cells
-If blood hits these cells, we need a clot!!! |
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How does Thrombin act?
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-Potent Activator of Platelets
-Removes Fibrinopeptides from Fibrinogen -Converts Fibrinogen to Fibrin |
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What does Factor 13a do? What type of Enzyme is it?
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-Chemically Cross-links Fibrin to give a stable clot
-Transglutaminase |
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What Chemically Cross-links Fibrin to give a stable clot?
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Factor 13a
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What is it called when a Thrombus dislodges and causes a block downstream?
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Thromboembolism
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Where and How is Tissue Factor Expression Induced?
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-Monocytes
-In Inflammation, Monocytes begin to make lots of TF when fighting infection |
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How and why does Atherosclerosis Increases the chances of a clot forming?
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-Oxidized LDLs can be found in the Subendothelial Space
-Monocytes are attracted to them and take up LDLs via Scavenger Receptor -This Activates Monocytes and upregulates Inflammatory Response and TF Production by Monocytes -Recruits other Leukocytes and essentially get a benign tumor growing -Cells may die -These Cells are now getting close (1 Layer) from the Lumen and May Rupture |
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What happens in atherosclerosis when rupture occurs?
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-Exposes TF to the blood
-Causes Clot to form |
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What is Progression?
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-When the Damage to a Clot is repaired
-Another Clot may occur -Can occur multiple times and lead to an occlusion |
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What is Hemophilia?
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Bleeding Disorder that involves the Clotting System
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What are the most common types of Hemophilia? How are these 2 related?
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-Factor 8a and 9a
-They are 2 halves of the same enzyme |
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Why in Hemophilia is there more bleeding in joints?
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-There is lots of TF in the skin so the pathway is usually fine there
-Very little TF in Joints -Causes bleeding in Joints |
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How do we test for the Integrity of the Plasma Clotting System?
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-PT test - Prothrombin Time
-aPTT test - activated Partial Thromboplastin Time |
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How does the PT test work?
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-Draw Blood
-Remove Plasma -Mix with excess calcium and TF -Measure time it takes to Clot |
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What is the PT Test Sensitive to?
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-Prothrombin
-Fibrinogen -Factos 5, 7, and 10 |
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What is INR? What is a normal INR? What is abnormal?
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-Ratio of a Patient's Clot time to a Normal Clot time
-1 is normal ->2 is considered to be Prolonged |
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What is the Intrinsic Pathway? What is another name for it? What is its importance?
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-Clotting activated by artificial surfaces
-Contact Pathway -We don't know what its role is and it doesn't seem like its necessary |
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How does the aPTT test work?
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-take Plasma
-Add Calcium -Use Artificial Activators - typically Clay -Tells us if Clotting is working |
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What is the aPTT test sensitive to?
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-Factors 5, 8, 9, 10, and 12
-Prothrombin -Fibrinogen -HK -PK |
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Which test can detect Hemophilia A and B?
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aPTT test
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What can we do to monitor Heparin Therapy?
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aPTT test
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Describe the structure of Fibrin.
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Dimer of Trimers
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Describe how Fibrin Polymerizes.
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-Fibrinopeptides are on Fibrin and keep it from Polymerizes
-Thrombin cleaves them off -Spontaneously Polymerizes and forms a clot |
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What is Antithrombin?
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-Natural Anticoagulant
-It is a Serine Protease Inhibitor |
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How does Antithrombin work?
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-It is a Serine Protease Inhibitor
-Irreversibly Inactives Serine Proteases -Not a very good inhibitor - needs Heparin |
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What are the main targets of Antithrombin?
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Factor 10a and Thrombin
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What does Heparin do?
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-Interacts with Antithrombin
-Makes it more of an anticoagulant -Accelerates ability of Antithrombin to Inactivate Factor 10 and Thrombin -Make Clotting Cascade harder to run |
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What is Warfarin? How does it work?
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-Anticoagulant drug
-Vitamin K helps Blood Proteins get Calcium, which they need for clotting -Warfarin Depresses the Vitamin K Dependent Carboxylation of Clotting Factors -Prothrombin, Protein S, Factors 7, 9, and 10 -Can be very dangerous |
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Why is Warfarin Potentially Dangerous
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-It affects lots of Enzymes in the Clotting Pathway
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What is Argatroban? Why might it be safer than Warfarin?
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-Direct Thrombin Inhibitor
-Only acts on 1 enzyme |
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What is Plasmin? What activates Plasminogen and turns it into Plasmin?
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-Plasmin digests Blood Clots during Wound-Healing
-tPA – Tissue-Type Plasminogen Activator -uPA – Urinary-Type Plasminogen Activator (Urokinase) |
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What do Thrombolytics do? Name a few.
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-Drugs that help digest Clots.
-Activase - tPA -Abbokinase - uPA -Streptase - Streptokinase |