Haemostasis

Question 1

Where and how are platelets formed?

Answer 1

in bone marrow

from cytoplasm budding off megakaryocytes

Question 2

What is the lifespan of platelets?

Answer 2

7-10 days

Question 3

What does the endothelium/vessel wall release when damaged/collagen is exposed?

Answer 3

Von Willibrand Factor

Question 4

What can cause failure platelet plug formation?

Answer 4

reduced number or function (drugs) of platelets
deficient collagen in blood vessel wall - Marfans syndrome and HSP
Von Willibrand disease

Question 5

What are the signs of platelet plug formation failure?

Answer 5

spontaneous bruising and purpura
mucosal bleeding: GI, conjunctival haemorrhage, menorrhagia, epistaxes
intracranial haemorrhage
retinal haemorrhage

Question 6

What is primary haemostasis?

Answer 6

vessel wall releases VWF and Glycoprotein 11b which causes platelet adhesion. platelets then release chemicals to attract platelet aggregation

Question 7

What is secondary haemostasis?

Answer 7

Tissue factor (TF) acitvates factor V11a this activates V + X which then cleaves prothrombin -> thrombin
once thrombin is cleaved it activates VIII/IX which activate V/X to make even more thrombin
thrombin cleaves fibrinogen to make fibrin

Question 8

How are fibrin clots broke down?

Answer 8

plasmin

Question 9

What are the things that cause failure of clots?

Answer 9

single clotting factor deficiency
multiple clotting factor deficiencies
increased fibrinolysis

Question 10

What are the normally occuring anticoagulants in the body?

Answer 10

protein C and protein S - switch off V and VIII

seriene protease inhibitors