Lecture 5: Introduction to Hemostasis and Thrombosis

Question 1

What are the steps in the Hemostasis: Response to Vascular Endothelial Injury (5)

Answer 1

(1) Formation of a Platelet Plug
(2) Propogation of Clotting process through coagulation cascade
(3) Stabilization of Platelet Plug by Fibrin Formation
(4) Termination of clotting through antithrombotic control mechanisms
(5) Removal of clot by fibrinolysis

Question 2

What is hemostasis?

Answer 2

Process of clot formation at the site of vessel injury

Question 3

What are the key players in hemostasis?

Answer 3

(1) Plasma proteins
(2) Platelets
(3) Vascular Endothelium

Question 4

What are the steps to the formation of a Platelet Plug? (5)

Answer 4

(1) Activation- collagen and thrombin activation
(2) Adhesion- deposition of activated platelets on injured epithelium
(3) Aggregation- platelet-platelet cohesion
(4) Secretion- the release of platelet granules
(5) Procoagulant activity- enhancement of thrombin generation via coagulation cascade on PLT surface

Question 5

Glycoprotein Ib/V/IX: von Willebrand factor (VWF) receptor facilitates what step to the formation of a platelet plug?

Answer 5

Platelet adhesion to subendothelium

Question 6

Glycoprotein IIb/IIIa: Fibrinogen, VWF receptor facilitates what step in the formation of a platelet plug?

Answer 6

Platelet/Platelet aggregation

Question 7

What is the purpose of the clotting cascade? (3)

Answer 7

(1) Sequential activation of a series of zymogens (inactive enzyme precursors) to active enzymes
(2) Results in significant stepwise amplification
(3) Goal: thrombin generation –> fibrin deposition –> reinforcement of initial platelet plug