USMLE Forum Archives - USMLE Step 1 - Pathology 17
Pathology 17
TheOne - 10-15-06 15:56
In the clotting process, as the hemostatic plug develops, fibrin polymerizes into monomeric threads which are held together by noncovalent bonds. Which clotting protein increases the strength of the clot by crosslinking the newly formed fibrin threads?
A. Factor XIII
B. High molecular weight kininogen (HMWK)
C. Plasminogen
D. Thrombin
E. von Willebrand Factor (vWF)
TheOne - 10-15-06 15:56
In the clotting process, as the hemostatic plug develops, fibrin polymerizes into monomeric threads which are held together by noncovalent bonds. Which clotting protein increases the strength of the clot by crosslinking the newly formed fibrin threads?
A. Factor XIII
B. High molecular weight kininogen (HMWK)
C. Plasminogen
D. Thrombin
E. von Willebrand Factor (vWF)
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#1
Re: Pathology 17
TheOne - 10-18-06 12:35 Explanation: The correct answer is A. Fibrinogen is cleaved by thrombin twice as it is activated to form fibrin. The initial cleavage causes it to polymerize and the second causes it to branch. Thrombin also activates Factor XIII to XIIIa, which crosslinks the fibrin strands and strengthens the clot. HMWK (choice B) is a cofactor in the intrinsic pathway that converts Factor XI to XIa. Plasminogen (choice C) is a central proenzyme in clot lysis. When plasminogen is converted to plasmin, it digests fibrin threads, as well as a number of protein factors including Factors V, VIII, XII, and prothrombin. Thrombin (choice D) is an enzyme derived from prothrombin. It converts fibrinogen to fibrin, and activates factor XIII. vWF (choice E) is a tissue-bound protein which is exposed with vascular trauma and helps in the process of platelet adhesion.
#2
Re: Pathology 17 galaxy - 05-27-10 19:45 facotr XIII also called fibrin stabilising factor.as the name indicates, it crosslinks fibrin and stabilises the clot...hence strengthens the clot...
#3
Re: Pathology 17 babbu5508 - 06-21-10 15:09 A. Factor XIII.Factor XIII is also known as fibrin-stabilizing factor or fibrinoligase.it crosslinks fibrin to form a stable clot...
#4
Re: Pathology 17 bingousmle - 06-30-10 22:17 
posted by TheOne on 10-18-06 12:35
Explanation: The correct answer is A. Fibrinogen is cleaved by thrombin twice as it is activated to form fibrin. The initial cleavage causes it to polymerize and the second causes it to branch. Thrombin also activates Factor XIII to XIIIa, which crosslinks the fibrin strands and strengthens the clot. HMWK (choice B) is a cofactor in the intrinsic pathway that converts Factor XI to XIa. Plasminogen (choice C) is a central proenzyme in clot lysis. When plasminogen is converted to plasmin, it digests fibrin threads, as well as a number of protein factors including Factors V, VIII, XII, and prothrombin. Thrombin (choice D) is an enzyme derived from prothrombin. It converts fibrinogen to fibrin, and activates factor XIII. vWF (choice E) is a tissue-bound protein which is exposed with vascular trauma and helps in the process of platelet adhesion.
Explanation: The correct answer is A. Fibrinogen is cleaved by thrombin twice as it is activated to form fibrin. The initial cleavage causes it to polymerize and the second causes it to branch. Thrombin also activates Factor XIII to XIIIa, which crosslinks the fibrin strands and strengthens the clot. HMWK (choice B) is a cofactor in the intrinsic pathway that converts Factor XI to XIa. Plasminogen (choice C) is a central proenzyme in clot lysis. When plasminogen is converted to plasmin, it digests fibrin threads, as well as a number of protein factors including Factors V, VIII, XII, and prothrombin. Thrombin (choice D) is an enzyme derived from prothrombin. It converts fibrinogen to fibrin, and activates factor XIII. vWF (choice E) is a tissue-bound protein which is exposed with vascular trauma and helps in the process of platelet adhesion.
nice explanation
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