Session 5- Haemostasis

Question 1

Describe the process of clotting

Answer 1

1. blood vessel is damaged
2. Initially vasoconstriction to cut of blood flow
3. platelet plug formation
4. Platelets activate and recruit further platelets and also activate the clotting cascade
5. clotting cascade makes fibrin that forms strands and binds to platelets

Question 2

Describe how a platelet plug is formed

Answer 2

platelets adhere to collagen on the subendothelial tissue
vWF helps in te adhesion of platelets to collagen
platelets form crosslinks to form the plug

Question 3

describe the two functions of vWF

Answer 3

aid in adherence of platelets to collagen

carrier for F8

Question 4

Name three chemicals that platelets release to activate the clotting cascade and more platelets

Answer 4

serotonin
thromboxane
ADP

Question 5

Describe the clotting cascade

Answer 5

intrinsic pathway- damage to the endothelial wall
extrinsic pathway- trauma

the common point of these two pathways is Factor 10
cleaves prothrombin to thrombin
- thombin feeds back on the clotting cascade and stimulates it– Thrombin burst
Thrombin cleaves fibrinogen into fibrin
fibrin forms strands and adheres to platelets

Question 6

Describe fibrinolysis.

Answer 6

Plasminogen–>plasmin that breaks down the fibrin mesh network

Question 7

Name 3 natural anticoagulants at what these do

Answer 7

protein C
protein S
antithrombin

Question 8

How a platelets produced?

Answer 8

Haematopoetic stem cells–>common myeloid progenitor cells–>megakaryocytes
off the megakaryocytes bud off platelets from the cytoplasm

Question 9

approximately what is the life span of platelets

Answer 9

7-10days

Question 10

Where are coagulation factors made?

Answer 10

in the liver

Question 11

name three general causes of thrombocytopenia

Answer 11

immune destruction
non immune destruction
reduced production

Question 12

name a cause of immune destruction of platelets and describe it and say the treatment used

Answer 12

Immune thrombocytopenia purpura

antibodies against growth proteins on platelts

treatment- Immuno suppression with corticosteroids

Question 13

why would a transfusion of platelets not work with immune thrombocytopenia purpura

Answer 13

platelets in the transfusion would just be destroyed

Question 14

Name a non immune cause of thrombocytopenia

Answer 14

Disseminated Intravascular Coagulation

Question 15

Name four causes of decreased production of platelets

Answer 15

drugs and toxins
B12/folate deficiency
Virus
Cancer in the bone marrow

Question 16

Name four consequences of thrombocytopenia

Answer 16

easy bruising
purpura
severe bleeding after trauma
intercranial haemorrhage