My Blood, Your Blood

Stem Cells Red Blood Cells White Blood Cells

Platelets Plasma Blood Types & Activity

Bloodology

Platelets are another important part or component of your blood. Platelets are sticky little pieces that help prevent bleeding and make a blood clot when a cut is made in the vessel wall. The picture above shows a great view of platelets using an electron microscope.


		When a stem cell decides to make platelets, it turns into a factory cell called a megakaryocyte. This is a very large cell with several nuclei. The megakaryocyte never leaves the bone marrow, but it does produce many tiny fragments. These fragments are actually the platelets - small pieces of cell material or cytoplasm.

		Platelets do leave the bone marrow and circulate freely in the bloodstream. Normally, platelets look round and smooth, but when they begin to work to plug up they become spiky and ragged around the edges. When an injury occurs to a blood vessel wall, the platelets respond by attaching themselves over the cut to form a temporary plug within minutes slowing the loss of blood.

The platelets also attract a protein found in plasma called fibrin and use it to form a dense netting that traps red blood cells and quickly becomes a clot.

From the outside of a cut, you can see the scab that forms over the wound. It looks hard and crusty. As long as there is still an unhealed hole in the blood vessel wall, the clot is constantly being formed, dissolved and reformed by fresh platelets so that bleeding is prevented. When the wound is finally healed by new cells growing over it, the clot will be cleared away and blood will begin to flow through the vessel again.



		I also learned that platelets help keep us from bleeding excessively. I really like the movie and I hope that other kids that watch it will enjoy it as I did.

		— Rosario, high school student