Heamostasis

Question 1

What is Haemostasis ?

Answer 1

The stopping of a haemorrhage

Question 2

What are the steps in Hamostasis?

Answer 2

1.Vasoconstriction -Decrease pressure downstream, Doesn’t happen at veins
Blood clotting
2. Platelet plug formation- Primary Heamostatic plug form activated platelets - seconds
3. Secondary Plug, Fibrin molecules - 30 mins

Question 3

How can it be assisted?

Answer 3

Therapeutically:
suturing
Pressure
Topical agent

Question 4

What is clotting?

Answer 4

Blood becomes solid when into contact with CT. controle by Clotting factors

Question 5

What destroys clots?

Answer 5

Fibrinolysis

Question 6

What does not clot blood?

Answer 6

WBC
Endothelial
Inactivated Platelets
RBC

Question 7

What are the 3 main players ?

Answer 7

Platelets
Process of blood clotting
Vascular Wall

Question 8

What activates platelets?

Answer 8

Collagen surfaces- extravascular
ADP- Amplification and Injured RBC
Thromboxane A2- Platelets aggregator - activated platelets 
Thrombin .
CATT

Question 9

How do Platelets activate?

Answer 9

1. Sick to sub endothelium with Von Willebrand factor
2. Aggregaten and fibrinogen Binds
3. Swell and change into sticky spheres
4. Secret factors to help growth - Fibrnogen , ATT

Question 10

What is required in synthesis of blood clotting Factors ?

And what other ?

Answer 10

Vit K

Cofactors- Phospholipids and calcium

Question 11

What type of Enzymes are clotting factors and what do they do?

Answer 11

Proenzymes activating the next = Amplification.

Question 12

what provides surface for clots?

Answer 12

Swelling of platelets during activation

Question 13

What are the 2 pathways and why are they called what they are?

Answer 13

1. Intrinsic - factors all in blood , no vessels needs to be broken only negative charged surface
2. Extrinsic - Extra cellular Tissue factor (Thromboplastin) Relesed from Damagae cells near site.
   Both can clot without platelets but not very well

Question 14

What happens to Vascular Wall ?

Answer 14

1. Media contracts
2. Sub-endothelium traps
   balances fibronlysis and clotting

Question 15

Factors affecting the formation of clots

Answer 15

1. Anticoagulants - Antithrobin 3, Protein C and S

2. Dilution by increasing blood flow

Question 16

What causes the evolution of a clot?

Answer 16

Platelets squeezed out by fibrin using actin myosin filaments pushing sides together and squeezing fluid

Question 17

What are the stages of Fibronolysis?

Answer 17

macrophages break down firbrin and sodeos plasmin . Plasminogen made in liver as is sterpokinase and urokinas . Activated by tPA and the Clotting cascade as Fibrin activates tPA.
FDP is made

Question 18

What is haemophilia?

Answer 18

Normal platelets but impaired clotting
A: Factor 8 deficiency .
B: Christmas diseases factor 9

Question 19

Whats does APTT. PT and Bleeding time measure

Answer 19

APTT- Intrinsic pathway
PT- Extrinsic
Bleeding time- Platelet plug

Question 20

What is tissue factor?

Answer 20

Factor 3- Extrinsic

Question 21

VW diesease

Answer 21

Deficiency in VW factor. Platelet plug and stabilising factor 8 . Prolonged APTT and Bleeding time .

Question 22

What is Thrombocytopenia?

Answer 22

Platelet too low . Spontaneous bleeding . pronged BT- Petechiae

Question 23

Cause of Thrombocytopenia

Answer 23

1. Decreased production due to Bone marrow infiltration
2. Decreased Platelet survival
3. Sequestration in spleen
4. Dilatational - Blood Transfusions

Question 24

What is DIC

Answer 24

Disseminated Intravascular Coagulation . Secondary to underlying cause
Formation of microthrombi. Activates fibrinolysis . Leads to haemorrhage
Transfusion of platelets ,FFP and cryoprecipitate

Question 25

Thrombophilia

Answer 25

Inherited and predisposition to thrombosis. Factor V Lieden leading to constant activated factor 10, deficiency -antithrobin , protein c and s , antiphospholid syndrome.