Hemostasis Flashcards
That thromboregulatory molecules does the endothelium produce?
- Arachadonic acid and Prostaglandin (PGI2)
- Nitric Oxide
Endothelin
What is the effect of PGI2 on endothelium?
it blocks platelet reactivity and induces vascular relaxation
What is the effect of NO on endothelium?
it is a short-lived vasodilator and inhibitor of platelet reactivity
What is the effect of endotheliun on endothelium?
It is a small polypeptide that regulates vascular tone through a G-protein coupled smooth muscle receptor
what regulates platelet production?
thrombopoeitin
what signals the platelets to react (aggregate)
exposure to underlying portions of the endothelium
what is the platelet’s response governed by?
- depth of injury
- location within the vascular bed (arterial vs. venous)
- individuals age (older = more reactive)
- hematocrit
- shear stress + blood flow
what is unique about the platelet plasma membrane?
it is an open canaliculi system (invagination of the plasma membrane) that allows for increased surface area for protein interactions and release of granules and for granules to be released without fusion with the PM and for the PM to spread out upon activation
Describe the platelet cytoskeleton
a marginal microtubular coil of actin and filamin connected to receptors
what is the most abundant protein in platelets?
actin
what organelles are found in platelets?
mitchondia, dense granules, alpha granules, lysosomes, and residual ribosome and RNA
NO NUCLEUS!!!
what do the alpha granules contain? where are they found?
found in platelets; store platelet specific proteins
what binding leads to platelet activation?
fibrinogen to alpha IIb Beta 3 integrin
what can alphaIIb Beta3 bind to?
fibrinogen, Von williebrand factor (VWF), fibronectin, throbospondin
How does alphaIIb Beta 3 bind to fibrinogen?
it recognizes the arginine Glycine aspartic acid (RGD) peptide sequence present on the LIGAND
