Question

1. platelets stop blood loss in all of the following ways except

a. by releasing cytokines to attract other cells to the site of damage
b. by triggering a reaction that promotes the formation of fibrin threads
c. by collecting and adhering at the site of damage
d. by forming a platelet plug

Explanation:

To solve this, we analyze each option based on platelet function in hemostasis:

• Option c: Platelets do collect and adhere at the site of damage (adhesion), which is part of stopping blood loss.
• Option d: Platelets form a platelet plug (aggregation) to seal the damaged vessel, helping stop blood loss.
• Option b: Platelets trigger the coagulation cascade that leads to fibrin thread formation (clot stabilization), so this is a way they stop blood loss.
• Option a: Platelets do not primarily release cytokines to attract other cells for blood loss prevention. Cytokine release by platelets is more related to inflammation or immune responses, not the main hemostatic mechanisms (adhesion, aggregation, coagulation initiation). So this is the exception.

Answer:

a. By releasing cytokines to attract other cells to the site of damage