Which statement about the participation of platelets in the coagulation cascade is true?

Which statement about the participation of platelets in the coagulation cascade is true?

• A. They generate fibrin directly
• B. They are not involved in coagulation
• C. They provide phospholipids for the formation of complexes
• D. They secrete plasmin

Answer: (C)

Activated platelets create a phospholipid-rich surface that is essential for the coagulation cascade to run efficiently. When platelets are activated, phosphatidylserine flips to the outer membrane, producing a negatively charged phospholipid surface. This surface, together with calcium, allows coagulation factors to assemble into functional enzyme complexes on the platelet membrane, notably the tenase and prothrombinase complexes. This assembly greatly speeds up thrombin generation and the conversion of fibrinogen to fibrin, helping to form a stable clot. Fibrin formation itself is the result of thrombin acting on fibrinogen, so platelets provide the arena for coagulation but do not directly generate fibrin themselves. Platelets are clearly involved in coagulation by enhancing thrombin production, not by producing fibrin directly or by secreting plasmin, which is involved in clot breakdown rather than formation.

Activated platelets create a phospholipid-rich surface that is essential for the coagulation cascade to run efficiently. When platelets are activated, phosphatidylserine flips to the outer membrane, producing a negatively charged phospholipid surface. This surface, together with calcium, allows coagulation factors to assemble into functional enzyme complexes on the platelet membrane, notably the tenase and prothrombinase complexes. This assembly greatly speeds up thrombin generation and the conversion of fibrinogen to fibrin, helping to form a stable clot.

Fibrin formation itself is the result of thrombin acting on fibrinogen, so platelets provide the arena for coagulation but do not directly generate fibrin themselves. Platelets are clearly involved in coagulation by enhancing thrombin production, not by producing fibrin directly or by secreting plasmin, which is involved in clot breakdown rather than formation.