Platelets

blood · healing · body systems

Clot creators. Platelets are super small pieces of cells that stick together when you get a cut, forming a blood clot that seals the wound and stops bleeding.

No brain needed. Platelets are unusual because they have no cell nucleus, the control center that most cells have, yet they still know exactly what to do when blood vessels get damaged.

Made in marrow. Platelets come from much bigger cells called megakaryocytes that live in your bone marrow and break apart into thousands of tiny platelet pieces that float into your bloodstream.

Mammal special. Only mammals like you, whales, and dogs have platelets, while other vertebrates like fish and birds have different cells called thrombocytes that do a similar job.

Quick responders. When a blood vessel gets injured, platelets immediately recognize the damage and race to the spot to form a plug that stops your blood from leaking out.