 |
 Stem
Cells Red
Blood Cells White
Blood Cells
 Platelets
Plasma
Blood
Types & Activity
Bloodology
 |
|
| Inactivated (smooth) platelet (stained blue)
among spiky, activated platelets as seen through a scanning
electron microscope. ©2000 Dennis Kunkel, Ph.D. |
Platelets are another important part or component of your blood.
Platelets are sticky little pieces that help prevent bleeding and
make the blood clot when a cut is made. 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, 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 get busy
plugging up cuts and wounds they become spiky and ragged around
the edges.
 |
|
When an injury occurs to a
blood vessel wall, the platelets respond by literally throwing
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. But on the inside, there's a lot
going on! 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.
|
|
|
|
