Intro to Haemostasis

Question 1

do platelets have nucleus

Answer 1

no

Question 2

platelet lifespan

Answer 2

7-10 days

Question 3

platelets are formed in the ______ _________ by ‘budding’ from _________________

Answer 3

bone marrow
megakaryocytes

Question 4

Endothelial (vessel wall) damage exposes collagen and releases ____ _______ ________ (VWF) and other proteins to which platelets have receptors - platelet ____________ at the site of injury

Answer 4

von willebrand factor

adhesion

Question 5

failure of platelet plug formation - causes

Answer 5

• vascular (e.g. vessel walls less strong)
• platelets (reduced number (thrombocytopaenia) or reduced function)
• Von Willebrand Factor (some families can have a deficiency which can lead to bleeding tendency)

Question 6

consequences of failure of platelet plug formation

Answer 6

• spontaneous bruising and purpura
• mucosal bleeding (epistaxes, GI, conjunctival, menorrhagia)
• Intracranial haemorrhage
• retinal haemorrhages

Question 7

screening test for primary haemostasis

Answer 7

• platelet count

Question 8

Tissue Factor activates factor ____

Answer 8

VII

Question 9

thrombin converts fibrinogen to _______ and also activates factors ___ and ___

Answer 9

fibrin
VIII and IX

Question 10

failure of fibrin clot - causes

Answer 10

• single clotting factor deficiency
• multiple clotting factor deficiencies
• increased fibrinolysis

Question 11

is single clotting factor deficiency usually hereditary or acquired

Answer 11

hereditary

Question 12

are multiple clotting factor deficiencies usually hereditary or acquired

Answer 12

acquired

Question 13

Fibrin is broken down by __________

Answer 13

plasmin

Question 14

plasminogen is broken down by _______ _________ ________ to plasmin

Answer 14

Tissue Plasminogen Activator (tPA)

Question 15

consequences of failure of fibrin clot formation

Answer 15

• may be combined primary/secondary haemostatic failure
• pattern of bleeding depends on single/multiple abnormalities and the clotting factors involved

Question 16

screening tests for fibrin clot formation

Answer 16

• prothrombin time
• activated partial thromboplastin time

Question 17

clinical approach to bleeding disorders - history

Answer 17

• bleeding/bruising
• duration (?lifelong)
• previous surgery/dental extractions

Question 18

clinical approach to bleeding disorders

Answer 18

history
drug history
family history
examinations (purpura, mucosal blood blisters, retinal haemorrhages etc)

Question 19

what does anti-thrombin do

Answer 19

a naturally occurring protein.
provides a counter mechanism to clot formation
binds to thrombin and switches it off, also binds and switches off some of the clotting factors like VIII and X

Question 20

thrombin recognises when haemostasis has been achieved, then it binds to _____________

Answer 20

thrombomodulin

Question 21

protein ___ and protein ___ switch off haemostasis and stop us bleeding too much

Answer 21

protein C and protein S

Question 22

what is hereditary thrombophilia

Answer 22

deficiency of naturally occurring anticoagulants that is hereditary

Question 23

thrombophilia - there is an increased tendency to develop ______ _______

Answer 23

venous thrombosis (DVT/PE)