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27 Cards in this Set
- Front
- Back
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What is Hemostasis?
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The cessation or termination of bleeding
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What are the three phases of Hemostasis?
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The vascular phase, the platelet phase, and the coagulation phase
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In the vascular phase, what is a Vascular Spasm?
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a 30 minute contraction triggered by a cut
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What are the 3 Steps in the Vascular Phase?
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1. Endothelial Cells contract and expose basal lamina to bloodstream
2. Endothelial Cells release chemicals and hormones to stimulate smooth muscle contraction and cell division 3. Endothelial cell membranes become “sticky” to seal off blood flow |
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When does the Platelet Phase begin?
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within 15 seconds after injury
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In the Platelet Phase, platelet adhesion (or attachment) occurs. What do platelets attach to?
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to sticky endothelial surfaces, to basal laminae, and to exposed collagen fibers
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In the Platelet Phase, platelet aggregation occurs (platelets stick together). What is the purpose for this?
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Platelet aggregation forms a platelet plug that closes small breaks
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Activated platelets release clotting compounds, what are these chemicals involved?
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- Adenosine diphosphate (ADP)
- Thromboxane A2 and serotonin - Clotting factors - Platelet-derived growth factor (PDGF) - Calcium ions |
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What is Prostacyclin and what is it released by?
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It is released by endothelial cells and it inhibits platelet aggregation
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The Coagulation Phase begins when?
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30 seconds or more after the injury
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What is a Blood Clot made up of?
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a fibrin network
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What does a Blood Clot cover?
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platelet plug
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What does a Blood Clot do?
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traps blood cells and seals off area
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What is another name for clotting factors?
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procoagulants
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What are procoagulants?
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platelets, proteins, or ions in plasma required for normal clotting
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What are Cascade Reactions?
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Chain reactions of enzymes and proenzymes
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What phase do Cascade Reactions happen in?
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The Coagulation Phase
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Cascade Reactions form 3 different pathways, what are they?
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Extrinsic, Intrinsic, and Common
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Where do Extrinsic pathways begin and where are they located?
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they begin in the vessel wall and are outside the blood stream
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Where do Intrinsic pathways begin and where are they located?
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They begin with circulating proenzymes and are within the blood stream
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Where are Common pathways?
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where intrinsic and extrinsic pathways converge
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Normally, how long does it take for a small puncture wound to stop bleeding?
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1-4 minutes
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What are 2 things that prevent clotting?
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anticoagulants (plasma proteins) and heparin (blood thinner produced in body)
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Calcium ions (Ca2+) and vitamin K are both essential to what?
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the clotting process
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After clot has formed, what do platelets do?
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contract and pull torn area together
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How long does Clot Retraction (what platelets do after clot has formed) take?
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30–60 minutes
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What is Fibrinolysis
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slow process of dissolving clot
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