haemostasis 1

Question 1

what are the two extremes of thrombosis?

Answer 1

• it might stop you from bleeding to death

- it could kill you with thrombosis

Question 2

what are platelets fragments of?

Answer 2

platelets are fragments of megakaryocytes

Question 3

what are the main mechanisms of homeostasis ?

Answer 3

• platelets and coagulation cascade

- and vessel constriction

Question 4

what is coagulation?

Answer 4

the process by which the blood is converted from a liquid to a solid state

Question 5

what is a von willebrand factor?

Answer 5

a plasma protein secreted by endothelial cells and platelets

Question 6

how is the homeostatic platelet plug formed?

Answer 6

• endothelial cells line the blood vessels and when there is damage the subendothelial layer which is rich in collagen is exposed

Question 7

how is collagen recognised?

Answer 7

• Von Willebrand Factor binds to the collagen and attracts platelets which bind to the Glycoprotein 1b Receptor (GlpIb) on the Von Willebrand Factor

or

Glycoprotein 1a Receptor on the platelets directly binds to the collagen
in the subendothelial layer

the circumstances may vary

Question 8

when are platelets activated?

Answer 8

-When the glycoprotein receptors are bound to something

Question 9

what happens when the platelets are activated?

Answer 9

the platelets will release ADP and PROSTAGLANDINS— activate other platelets so the platelets aggregate
(thromboxane)