when do platelet plugs happen?
small cuts
diameter of platelets
1-4 um
who makes platelets?
megakaryocytes from bone marrow
megakaryocyte function
fragment in bone marrow or in blood as they squeeze through capillaries
conc. of platelets in blood
150 000-400 000 / uL
general structure of platelets
no nuclei, some organelles
do platelets reproduce?
no
What is in the cytoplasm of platelets?
1.actin and myosin
2. ER and Golgi residues
3.mitochondria and enzyme systems (ATP+ADP)
4.fibrin stabilising factor
5. platelet derived growth factor
what do Golgi and ER do?
make enzymes and store calcium
what do enzymes systems do
make prostaglandin and involved in ATP+ADP
who cause endothelial, smooth muscles and fibroblasts to grow and multiply
platelet-derived growth factor
what is on platelet membrane?
glycoproteins, phospholipids,
what do surface glycolproteins do?
repulses adherence to endothelium and causes adherence to injured areas
who in the membrane has a part in clotting?
phospholipids
what is the half life of platelets?
8-12 days
who discard platelets?
macrophages in spleen
which granules are in platelets?
alpha and dense granules
what are alpha granules
proteins. include clotting factors, and PDGF
what are dense granules
non protein released in response to platelet activation , including ADP, serotonin, other adenine nucleosides
