Platelets are tiny blood cells that help your body form clots to stop bleeding. If one of your blood vessels gets damaged, it sends out signals that are picked up by platelets. The platelets then rush to the site of damage and form a plug, or clot, to repair the damage.
The process of spreading across the surface of a damaged blood vessel to stop bleeding is called adhesion. This is because when platelets get to the site of the injury, they grow sticky tentacles that help them adhere. They also send out chemical signals to attract more platelets to pile onto the clot in a process called aggregation.
Facts about platelets
Platelets are made in your bone marrow along with your white and red blood cells. Your bone marrow is the spongy center inside your bones. Another name for platelets is thrombocytes. Healthcare providers usually call a clot a thrombus. Once platelets are made and circulated into your bloodstream, they live for 8 to 10 days.
Under a microscope, a platelet looks like a tiny plate. Your healthcare provider may do a blood test called a complete blood count to find out if your bone marrow is making the right number of platelets:
A normal platelet count is 150,000 to 450,000 platelets per microliter of blood.
Risk for spontaneous bleeding develops if a platelet count falls below 10,000 to 20,000. But when the platelet count is less than 50,000, bleeding is likely to be more serious if an individual is cut or bruised.
Some people make too many platelets and can have platelet counts from 500,000 to more than 1 million.