21. Hemostasis

Question 1

Where is thrombopoietin produced?

Answer 1

It is produced by the liver and to a lesser extent, the kidney.

Question 2

What all is contained in the vesicles of a platelet?

Answer 2

ADP

Thromboxane A2

Fibrin stabilizing factor

Platelet derived growth factor

Question 3

What is the function of cyclooxygenase 1?

Answer 3

Conversion of arachidonic acid into prostaglandins (like thromboxane A2)

Question 4

What are the four steps of hemostasis?

Answer 4

Vascular spasm

Platelet plug

Blood clot

Repair

Question 5

What three chemicals act as short term vasoconstrictors to assist with the vascular spasm phase of hemostasis?

Answer 5

Thromboxane A2

Platelet factor

Serotonin

Question 6

What are the two steps for the formation of a platelet plug?

Answer 6

• Collagen is exposed -

Step 1: Von Willebrand factor binds

Step 2: Platelet’s collagin receptor binds and is activated

Question 7

What does thrombin do to help form a clot?

What does it do to get rid of a clot?

Answer 7

To form the clot: fibrinogen → fibrin

To get rid of the clot,

Protein C → Activated protein C

Question 8

What is the function of protein C in clot removal?

Answer 8

It inactivates the tPA inhibitor

This allows tissue plasminogen activator (tPA) to activate plasminogen into plasmin.