Anticlotting Mechanism

Question 1

A. Endothelial Surface Factors

1. Smoothness of the _______ cell surface which prevents ______ activation of the _______ clotting system
2. ________ on the endothelium which _____ clotting factors and platelets
3. ________ (endothelial protein)
   binds with thrombin and forms thrombomodulin- thrombin
   complex to activate ________ that along with protein S inactivate _____ & _____

Answer 1

endothelial; contact; intrinsic

Glycocalyx; repels

Thrombomodulin; protein C; V & VII

Question 2

B. Antithrombin Action of Fibrin and Antithrombin III

Thrombin formed from the prothrombin becomes ______ to the fibrin fibers as they develop.

This adsorption helps prevent the spread of thrombin into the remaining blood and, therefore, prevents excessive ______ of the clot.

The thrombin that does not adsorb to the fibrin fibers combines with
_________, which blocks the effect of the thrombin on the fibrinogen.

Answer 2

Adsorbed;
spread;
antithrombin III

Question 3

C. Heparin

______ is a naturally produced anticoagulant in the body.

It is produced by _______ abundant in liver and lungs where heparin might be needed.

Increased risk for _______ due slow venous blood flow in these organs.

_______ also secrete heparin.

Answer 3

Heparin;
mast cells
blood clot
Basophils

Question 4

Mechanism of Action of Heparin

i. Prevents _________ by its antithrombin activity. It directly suppresses the activity of ________.

Answer 4

Blood clotting; thrombin

Question 5

ii. Combines with antithrombin III (a ____________ present in
circulation) and removes thrombin from circulation.

Answer 5

protease inhibitor

Question 6

iii. Activates ________

iv. Inactivates the ________ of other clotting factors like IX, X, XI
and XII

Answer 6

antithrombin III;
active form

Question 7

Commercially available heparin is widely used as an ________ in
clinical practice.

Answer 7

anticoagulant

Question 8

Heparin

i.To prevent _______ blood
clotting during surgery.

ii. While passing the blood through
artificial kidney for ________.

iii. During _______ surgery, which
involves heart lung machine.

iv. To preserve the blood before
__________.

Answer 8

intravascular;
dialysis;
cardiac
transfusion