What Are Blood Platelets?

Blood platelets are cells that aid in the clotting process, according to the American Red Cross. They collect at the lining of the blood vessels in the event of a cut and help stop the flow of blood.

Hopkins Medicine states that blood platelets are shaped like small plates but change their shape while in the clotting process, in which they grow long tentacles. According to the American Red Cross, platelets are made in the bone marrow and live in the circulatory system when not in action. People can also receive platelets through a blood transfusion.

A healthy blood platelet count is approximately 150,000 to 450,000 for each microliter of blood, according to Hopkins Medicine. Having too many platelets is thrombocytosis, and having too little is thrombocytopenia.