Coagulation and Patrick J. P.

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  • Topic: Coagulation, Hemostasis, Thrombus
  • Pages : 3 (464 words )
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  • Published : February 14, 2013
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Hemostasis
"How does our body handle bleeding?" Model 1: blood clotting

platelet

serotonin (vasoconstrictor)

prothrombin activator

(active)

Ca2+
Prothrombin
(inactive)

thrombin !

fibrinogen
(soluble)

fibrin!
(insoluble)

Part 1: Platelet Plug Formation

Part 2: clot formation (occurs after plug formation)

Critical thinking questions: 1. Although not pictured in the model above, the first thing that happens when a blood vessel is torn is vasospasm, in which the walls of the blood vessel contract. As a group, come up with an explanation for this phenomenon.

2. Look at (part 1 of) the model. Platelets are always present in the blood yet they don't (usually) form a plug. When they escape through a break in the blood vessel, what substance do they contact that induces them to become sticky and form a platelet plug?

3. According to part 2 of the model, what two substances do platelets secrete after forming a platelet plug?

4. What is the inactive form of thrombin called?

Text © 2011 Patrick J. P. Brown, All images are the author’s creation, used under the GNU fair use license or are otherwise in the public domain.

5. Why can't thrombin be in its active form in regular blood circulation?[what would happen if it was?]

6. In the past you have learned about enzymes and cofactors. Both are necessary to convert prothrombin into thrombin. According to the model, what is the enzyme that converts prothrombin to thrombin?

7. What cofactor does this enzyme require?

Memorization fact: An abnormal clot is called a thrombus, once that clot leaves the site of formation and enters circulation, it’s called an embolus. If an embolus gets lodged somewhere it’s called an embolism Application 8. What is the stringy material visible in this scanning electron micrograph of a blood clot?

9. Tissue Plasminogen Activator (TPA), Heparin, and Warfarin are all fibrinolytic substances. Think about what the suffix "-lytic" means and...
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