Platelets are small cells that circulate in the blood. They are involved in the formation of blood clots and the repair of damaged blood vessels.
When a blood vessel is injured, platelets stick to the damaged area and spread along the surface to stop the bleeding (this process is called adhesion). At the same time, chemical signals are released from small sacks inside the platelets called granules (this process is called secretion). These chemicals attract other platelets to the site of injury and make them clump together to form what is called a platelet plug (this process is called aggregation).
Sometimes the platelet plug is enough to stop the bleeding. However, if the wound is large, other proteins called clotting factors are recruited to the site of injury. These clotting factors work together on the surface of the platelets to form and strengthen the blood clot.
Platelet function disorders are conditions in which platelets don’t work the way they should, resulting in a tendency to bleed or bruise. Since the platelet plug does not form properly, bleeding can continue for longer than normal.
Since platelets have many roles in blood clotting, platelet function disorders can lead to bleeding disorders of various intensities.