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Flashcards in Heamostasis Deck (25):
1

What is Haemostasis ?

The stopping of a haemorrhage

2

What are the steps in Hamostasis?

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

3

How can it be assisted?

Therapeutically:
suturing
Pressure
Topical agent

4

What is clotting?

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

5

What destroys clots?

Fibrinolysis

6

What does not clot blood?

WBC
Endothelial
Inactivated Platelets
RBC

7

What are the 3 main players ?

Platelets
Process of blood clotting
Vascular Wall

8

What activates platelets?

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

9

How do Platelets activate?

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

10

What is required in synthesis of blood clotting Factors ?
And what other ?

Vit K
Cofactors- Phospholipids and calcium

11

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

Proenzymes activating the next = Amplification.

12

what provides surface for clots?

Swelling of platelets during activation

13

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

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

14

What happens to Vascular Wall ?

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

15

Factors affecting the formation of clots

1. Anticoagulants - Antithrobin 3, Protein C and S
2. Dilution by increasing blood flow

16

What causes the evolution of a clot?

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

17

What are the stages of Fibronolysis?

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

18

What is haemophilia?

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

19

Whats does APTT. PT and Bleeding time measure

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

20

What is tissue factor?

Factor 3- Extrinsic

21

VW diesease

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

22

What is Thrombocytopenia?

Platelet too low . Spontaneous bleeding . pronged BT- Petechiae

23

Cause of Thrombocytopenia

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

24

What is DIC

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

25

Thrombophilia

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