Coagulation Physiology & Disorders

Question 0

What happens in primary haemostatsis?

Answer 0

Platelets bind to breach

Forms platelet plug

Question 1

What initiates coagulation?

Answer 1

Damage to vessel wall

Question 2

What happens in secondary haemostatsis?

Answer 2

Fibrin clot forms

Stabilises platelet plug

Question 3

What prevents clots in intact vessels?

Answer 3

Endothelial cells

Question 4

What acts as a bridge between vessel wall & platelet?

Answer 4

VWF

Question 5

What makes the fibrin clot?

Answer 5

Coagulation factors

Question 6

What are the 2 main features of prothrombin (coagulation factor)?

Answer 6

Enzyme site

Glutamic acid tail

Question 7

What does vitamin K do to the Glutamic acid tail of prothrombin?

Answer 7

It converts it into a negatively charged gamma carboxylated Glutamic acid (which can stick to surface of platelets)

Question 8

What converts Vitamin K epoxide back to Vitamin K?

Answer 8

Vitamin K reductase

Question 9

What enzyme does Warfarin inhibit in order to thin the blood?

Answer 9

Vitamin K reductase

Question 10

What is produced locally at vessel damage that thickens blood?

Answer 10

Thrombin

Question 11

What does thrombin cleave?

Answer 11

Fibrinogen —> fibrin

Fibrin spontaneously polymerises to form clot

Question 12

What process breaks down the fibrin clot?

Answer 12

Fibrinolysis

Question 13

What happens in fibrinolysis?

Answer 13

Plasminogen binds to fibrin & it is activated
Plasminogen—>plasmin
Plasmin cleaves fibrin & breaks down clot

Question 14

What converts plasminogen —> plasmin?

Answer 14

Tissue plasminogen activator

Question 15

What deficiency is seen in Haemophilia A?

Answer 15

Factor 8 deficiency

Question 16

What deficiency is seen in Haemophilia B?

Answer 16

Factor 9 deficiency

Question 17

How is Haemophilia inherited?

Answer 17

X linked recessive

Mother gives to son

Question 18

Name a common place of bleeding in haemophilia & what this causes

Answer 18

Joint & muscle

Chronic joint damage & disability

Question 19

Is Von Willebrand disease more or less common than haemophilia?

Answer 19

More common

Question 20

What can’t form in VW disease?

Answer 20

The platelet plug

⬇️ platelet vessel wall adhesion
⬇️ platelet aggregation
⬇️ factor 8

Question 21

What can’t form in haemophilia?

Answer 21

The fibrin clot

Question 22

What 2 tests do you do for a bleeding patient?

Answer 22

FBC
- (low platelets, Hb, MCV)

Coagulation screen
- (PT, aPTT, TCT, Fibrinogen level)

Question 23

What is measured to see how we’ll warfarin is working?

Answer 23

INR

Question 24

What is the target INR?

Answer 24

2-3 or 3-4

Depending on bleeding risk

Question 25

What converts

Fibrinogen ➡️ fibrin

Answer 25

Thrombin

Question 26

What causes Vitamin K deficiency?

Answer 26

Warfarin
New borns
Critically ill
Obstructive jaundice
Malabsorption

Question 27

Causes of DIC (abnormal clotting & bleeding, life threatening)

Answer 27

Infection (meningococcus)
Malignancy
Obstetric (placental abruption, eclampsia, amniotic fluid embolism)
Shock
ABO mismatch
Venom (snake, spider)

Question 28

Thrombocytopenia means…

Answer 28

Low platelet count

Question 29

What is seen clinically in DIC

Answer 29

Generalised oozing (bento puncture sites)

Question 30

What is seen in blood test if DIC patient?

Answer 30

Prolonged PT, aPTT, TT
Thrombocytopenia
Low fibrinogen
Raised D-dimer

Question 31

What test tells you if a prolonged thrombin time is due to heparin?

Answer 31

A reptilase time