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Key Terms
Hemostasis
Balance between clotting and bleeding
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Vascular system
Blood vessels
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Platelets (thrombocytes)
Aggregation and adhesion form small clumps at injured site, limiting blood loss
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Megakaryocyte
- Largest cell in the bone marrow, rarely seen in peripheral blood.
- Platelets are released from the megakaryocyte cytoplasm and enter the peripheral blood.
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Endoreduplication
Cell division without cytoplasmic division (nucleus divides, but the cytoplasm does not)
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Fibrinolytic System
Plasmin dissolves fibrin
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Vasoconstriction
- Blood vessel's diameter decreases.
- First responder to injury
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Blood Clot
Clot main component is protein (fibrin, glue that fills in the hole of blood vessels)
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Serum
Liquid portion of a blood specimen after allowed to clot.
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Plasma
Liquid portion of a blood specimen after being centrifuged.
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Arteries/Veins
- Arteries: vessels transporting oxygen blood away from the heart.
- Vessels: transporting de-oxygenated blood back to the heart. Thinner and weaker than arteries.
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Arteriole/Venule
Artery--Arteriole--Capillary--Venule--vein
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Capillary
Middle ground between arteries and veins, where oxygen is delivered to the cells. Very thin, only a single cell layer thick.
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Tunica intima
Innermost, single endothelial cell layer in contact with blood. Underneath lies collagen. Non-reactive with blood.
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Tunica adventia
- Outer layer
- Connective tissue, nerve endings and the vas vasorm (layers of tissue on outside)
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Endothelial
- Intact
- Inert with blood components.
- Traumatized, then physiologically active synthesizes and stores active chemicals
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Collagen
Binds to platelet membrane GP Ib/IIa
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Plasminogen activators
starts fibrinolysis clot dissolution
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Prostacyclins
Inhibit platelet aggregation and adhesion
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Glycocalyx
- Fluffy outer coat
- Regulates shape
- Platelet adhesion and aggregation
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Alpha granules
(most abundant)
- vWF
- Thrombospondin
- Fibronectin
- Platelet fibrinogen
- Platelet factor IV
- Platelet adhesion
- Platelet aggregation
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Dense granules
- ADP
- Serotonin (Vasoconstriction)
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Platelet count
- Normal count doesn't necessary mean normal function.
- Manual counts are usually performed to confirm questionable automated platelet counts.
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Platelet estimates
- Performed on all CBCs
- Average # platelets per oil immersion field x 15,000
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Platelet adhesion
Platelets "stick" to the surfaces of damaged blood vessels
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Platelet aggregation
Platelets sticking to each other at the damaged vessel
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GP IIb/IIIa
attaches to other platelets with Fibrinogen
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Aspirin
- Impairs synthesis of platelet's Thromboxane (TXA2).
- TXA2 stimulates platelet granule release.
- Platelet aggregation is impaired for the entire life span of the platelet.
- Inhibit Platelet function (aggregation) and clotting is inhibited.
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Plavix
- Inhibits platelet GP IIb/IIIa
- Inhibits function
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Epinephrine
Promotes vasoconstriciton
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Serotonin
- Plasma hormone
- Promotes vasoconstriction
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Factor 1 Fibrinogen
Soluble
- Plasma protein precursor to fibrin
- Fibrinogen---Fibrin clot (insoluble)
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Factor 2 Prothrombin
- Stable precursor of thrombin
- Prothrombin--Thrombin (active)
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Factor 5: Proaccelerin
- Very liable (1/2 life=16 hours)
- Consumed during clotting
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Factor 8: Anti-Hemophiliac Factor
- 2 complex components
- High molecular: vWF, VIII RCo (plt. aggregation), VIII Ag (Antigenic site)
- Low molecular: VIII C (procoagulant), VIII Ag (Antigenic site)
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Factor 9:
Plasma Thromboplastin component
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Factor 11
Plasma thromboplastin antecedent
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Factor 13
Fibrin Stabilizing Factor
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Fibrinogen Group I
- 1,5,8,13
- Consumed during clotting
- 5 and 8 extremely liable
- Increased in inflammation, pregnancy, oral contraceptives.
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Prothrombin Group II
- 2,7,9, 10
- NEEDS Vitamin K for synthesis
- Not consumed during clotting (except for 2)
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Contact Group III
- 11, 12, PK (Fletcher), HMWK (Fitzgerald)
- Stable storage/not consumed during clotting.
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Intrinsic Pathway
Activated by contact with negatively charged solid surfaces (collagen, glass)
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Extrinsic Pathway
Activated by contact with tissue phospholipids (thromboplastin) following endothelial damage
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Common pathway
Represents the merging of the Extrinsic and Intrinsic pathways.
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Warfarin
(Coumarin,Coumadin)
PT
- Oral anticoagulants
- Effective for long term, self-medication
- Blood thinner
- Vitamin K antagonists (inhibit Vitamin K)
- Group II (2,7,9,10)
- Synthesis in liver
- Slow acting (8-12 hours)
- Long duration (72 hours)
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Heparin IV
Anti-coagulant
PTT
- Given in a hospital setting-not @ home.
- Inhibits thrombin by enhancing ATIII
- Fast acting (effective within mins after IV dosage)
- 1/2 life=1 hour
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Vitamin K
- Makes the body system avoid excessive blood flow.
- People without Vitamin K prone to bruising and bleeding.
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Fibrinolysis
Proteins begin the process of limiting the formation and eventual remove the clot.
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TPA Tissue Plasminogen Activator
- Starts fibrinolysis
- Activates plasminogen--Plasmin breaks up fibrin
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Fibrin Degradation Products
- Fragments X, Y, D, E
- Pieces of fibrin
- Inhibit platelet aggregation, fibrin polymerization, thrombin.
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Protein C
- Inhibits Factor 5 and 8
- Synthesized in liver
- Vitamin K dependent
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Protein S
- Natural anticoagulants
- Major system involved in the regulation of blood coagulation and in the protection against thrombotic diseases
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ATIII
- Most active natural anti-coagulant
- Inhibits thrombin (Factors 9, 10, 11, 12)
- Synthesized in liver, platelets, endothelium
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Clot buster
Give to people with heart attack symptoms or go through one
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Thromboplastin
- Any tissue (non-plasma) phospholipid substance.
- Cell membrane guts
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