Which term is the proper name for the chemical released by damaged blood vessels?

Which term is the proper name for the chemical released by damaged blood vessels?

• A. Fibrinogen
• B. Hemoglobin
• C. Platelet factor 4
• D. Von Willebrand Factor (VWF)

Answer: (D)

When a blood vessel is damaged, the endothelium releases von Willebrand factor from storage granules. This factor serves as a bridge between exposed subendothelial collagen and platelets, binding to collagen and to the platelet receptor GPIb to anchor platelets at the injury site and kick off the formation of the platelet plug. It also helps by carrying and stabilizing factor VIII in the blood, protecting it from breakdown. The other options don’t fit this scenario: fibrinogen is a plasma protein involved in platelet aggregation after activation, not something released specifically by damaged endothelium; hemoglobin remains inside red blood cells and isn’t a hemostatic mediator; platelet factor 4 is released from platelets themselves during activation, not directly from the damaged vessels.

When a blood vessel is damaged, the endothelium releases von Willebrand factor from storage granules. This factor serves as a bridge between exposed subendothelial collagen and platelets, binding to collagen and to the platelet receptor GPIb to anchor platelets at the injury site and kick off the formation of the platelet plug. It also helps by carrying and stabilizing factor VIII in the blood, protecting it from breakdown.

The other options don’t fit this scenario: fibrinogen is a plasma protein involved in platelet aggregation after activation, not something released specifically by damaged endothelium; hemoglobin remains inside red blood cells and isn’t a hemostatic mediator; platelet factor 4 is released from platelets themselves during activation, not directly from the damaged vessels.