Which of the following is necessary for platelet aggregation? ...

[rachel9]

Which of the following is necessary for platelet aggregation?
 
  a. Protein S
  b. Kallikrein
  c. Vitamin K
  d. Fibrinogen

Question 2

What happens to the fibrin monomers created when thrombin cleaves fibrinopeptides A and B from fibrinogen?
 
  a. Immediately inactivated to prevent excess clotting
  b. Converted to plasminogen
  c. Digested quickly by tissue plasminogen activator (TPA)
  d. Polymerize and are stabilized by factor XIIIa

[Athena23]

Answer to Question 1

ANS: D
Platelet aggregation, the binding of platelets to one another, requires fibrinogen.

Answer to Question 2

ANS: D
Once thrombin splits fibrinopeptides A and B from fibrinogen, the fibrin monomers are formed. These spontaneously polymerize to form the initial soluble fibrin polymer, which is cross-linked by XIIIa and then becomes insoluble. Fibrin monomers spontaneously polymerize to form the fibrin clot, which is then stabilized by factor XIIIa. TPA activates plasminogen to plasmin, which lyses the clot.