Hemostasis Flashcards
What do platelets have on the surface
Collage receptors
What do the collagen receptors on the surface of platelets bind with
.vWF which then anchors the platelets to the exposed collagen
How does thrombopoeitin bind to platelets
Via mPL on platelets and the Jack2/Stat5 protein
What does very increased platelets mean
Increased TPO bound to mPL which means the platelets internalize the excess TPO and destroy it which leads to decreased TPO
What does decreased platelets lead to
Decreased bound TPO which means for free TPO available for clotting
The production of platlets is controlled by what
TPO and chromosome 3
What are the four steps of hemostasis
- Vascular spasm
- Formation of a platelet plug (primary coag.)
- Formation of a blood clot (secondary coag.)
- Repair of damage
What causes the vascular spasm in an injured vessel
SM contraction as well as serotonin and thromboxane A2
Do N.’s cause the vascular spasm
NO, they may add to it, but they are not essential
What does the activated platelet do
Swells and extends podocytes
What are the steps from the attachment of platelets to the collagen via vWF
- Platelets swell
- Contraction of platelets connected to fibrin
- Granules expelled from platelets
- Platelets attract more to them via thromboxane A2 and ADP
What does the clot retraction do/entail
What is required to do this
Gets rid of excess serum within clot
Platelets bind to fibrin polymer and the actin/myosin in the platelet causes a contraction
Ca is required
What is platelet derived growth factor secreted from and what does it do
Secreted from platelets
Stimulates fibroblast to grow into area which then differentiate into whatever is needed
Where is plasminogen made
In the liver, not active and floating in the plasma
What is plasminogen activated by
TPA
