NEET MDS

The Power Course

Thrombin, what is correct



Choices

1 ) Anticoagulant
2 ) Activates factor X
3 ) Converts fibrin to fibrinogen
4 ) Activated by Protein C and S

Explanation


Thrombin in circulation is a procoagulant, but binding with thrombomodulin i.e. thrombin-thrombomodulin acts as an anticoagulant. This complex activates Protein C and Protein S(anticoagulant) see below how the fibrinolytic system is activated.

Thrombin does not activate factor X

Thrombin converts fibrinogen to fibrin

Thrombomodulin-thrombin complex

Thrombomodulin is a thrombin binding protein secreted by endothelial cells of vessels except cerebral vessels. This binds with thrombin, forming a complex, which has anticoagulant properties.

Thrombomodulin-thrombin complex activates Protein C. Activated protein C inactivates factor V and VIII with protein S. 

Activated Protein C inactivates inhibitor of tissue plasminogen activator (t-PA) so more plasminogen is converted to plasmin, leading fibrinolysis (clot breaking).

Ref Ganong chapter 31 edition 26.


Answer

Anticoagulant

Last Modified : 25-Dec-2019

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