Antiplatelets prevent blood clots. Platelets and fibrin form clots to prevent bleeding
Platelet clotting steps. Adhesion, Activate, Aggregate
Antiplatelets prevent platelet aggregation Paper items, like plates, stick together 
The fibrin, together with platelets, forms a hemostatic plug or clot over a wound site 
Adhesion begins with exposure. Like platelet being exposed to collagen
Activation. Smoke sends signals to more smokers
Aggregation. More smokers will gather in the same spot
Aspirin blocks cyclooxygenase
Aspirin permanently blocks platelets from aggregating during life of platelet (3 - 7 days)
*Platelet, fibrin, plasmin, plasminogen, thrombin