PHIL 1000X Study Guide - Final Guide: Collagen, Fibrinolysis, Coagulation
Course CodePHIL 1000X
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MODULE Y3 - BLOOD
Hemostasis & Coagulation
When you have finished this unit, you should be able to:
1. Define hemostasis.
a. The process of keeping blood within a damaged blood vessel
2. List the stages/steps involved in sealing a cut or torn blood vessel.
a. Immediate constriction of damaged vessels
b. Mechanical blockage of the hole by a platelet plug (they then activate and
release cytokines; reinforce vasoconstriction and activate more platelets)
c. Formation of a fibrin protein mesh (stabilizes platelet plug to form a clot)
d. vessel repairs itself, clot retracts when fibrin is dissolved by plasmin
3. Describe how a platelet plug is formed.
4. Define the actions of thromboxane A2, heparin, tissue plasminogen activator (t-PA), and
a. TXA2 (Thromboxane A2): Vasoconstrictor, Platelet aggregator
b. Heparin:a compound occurring in the liver and other tissues that inhibits
blood coagulation. A sulfur-containing polysaccharide, it is used as an
anticoagulant in the treatment of thrombosis.
c. Tissue plasminogen activator (T-PA): Tissue plasminogen activator is a
protein involved in the breakdown of blood clots. It is a serine protease found
on endothelial cells, the cells that line the blood vessels
d. Fibrin:an insoluble protein formed from fibrinogen during the clotting of blood.
It forms a fibrous mesh that impedes the flow of blood.
5. Sketch the intrinsic and extrinsic blood coagulation pathways, and explain why they are
termed "intrinsic" and "extrinsic".
a. REFER TO FIGURE 16-10
c. Intrinsic Pathway: Exposed collagen + XII
e. Extrinsic Pathway: Exposed Tissue Factor + VII
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