Haemostasis

Question 1

Define Haemostasis and state 2 functions

What are the 3 steps in Haemostasis

Answer 1

The stopping of bleeding

Prevents bleeding
Prevents unnecessary coagulation

Make clot
Control clotting
Breakdown of clot (Fibrinolysis)

Question 2

What 5 things are essential for Haemostasis

Answer 2

Keep blood moving 
Blood vessels 
Platelets
Coagulation factors
Anticoagulant factors

Question 3

Compare primary and secondary Haemostasis

Answer 3

Primary: Platelets aggregate to form a plug at the vessel hole

Secondary: Plug strengthened with fibrin filaments

Question 4

Describe Platelet Adhesion

Answer 4

• Damage to vessel wall
• Exposure of underlying tissues
• Platelets adhere to collagen via vWF receptor

Question 5

Describe platelet activation

Answer 5

• Platelets secrete ADP and other substances to become activated and activate other platelets
• Involved in activation of clotting cascade
• Secrete coagulation factors from internal stores

Question 6

Describe Platelet Aggregation

Answer 6

Cross linking of platelets to form a platelet plug

Question 7

Identify 7 mediating factors that stimulate clotting

Answer 7

Platelet receptors- Glycoprotein complexes
Von willebrands factor 
Fibrinogen 
Collagen surfaces 
ADP
Thrombin
Thromboxane

Question 8

Outline the clotting cascade mechanism to make fibrin

Answer 8

1. Intrinsic and extrinsic pathways activate Factor X
2. Factor Xa activates Prothrombin II-> Thrombin IIa
3. Thrombin IIa activates Fibrinogen 1-> Fibrin Ia

Question 9

What are 2 ways that coagulation is controlled

Answer 9

• Natural anticoagulants inhibit activation of clotting cascade
• Clot destroying proteins, which are activated by the clotting cascade

Question 10

Name 4 Natural Anticoagulants

Answer 10

Protein C
Protein S
Antithrombin
Tissue factor pathway inhibitor

Question 11

What are Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT)

Answer 11

PT: A diagnostic test used to evaluate the extrinsic and common pathway

APTT: A diagnostic test used to evaluate the intrinsic and common pathways

Question 12

A problem with which factors cause Prolonged PT

Which pathways are each factor in

Answer 12

7- Extrinsic

5,10,Prothrombin, Fibrinogen- Common

Question 13

A problem with which factors cause Prolonged APPT

Which pathways are each factor in

Answer 13

8,9,11,12- Intrinsic pathway

5,10, Prothrombin, Fibrinogen- Common Pathway

Question 14

What are D dimers

Answer 14

Fibrin degradation products

Question 15

What does Von Willebrand Factor do

Answer 15

Involved in;

• Platelet aggregation
• Platelet adhesion
• Carries factor 8

Question 16

What are 3 functions of the vessel wall

Answer 16

• Vasoconstriction
• Production of Von Willebrand’s Factor
• Exposure of collagen and tissue factor, initiating activation of clotting factors

Question 17

Outline fibrinolysis

Answer 17

Plasminogen activator activates PLASMIN from PLASMINOGEN

Plasmin breaks down FIBRIN to D-Dimers

Question 18

What are 3 causes of bleeding disorders and what are the 2 types

Answer 18

Inherited and acquired

Abnormalities in;

• Vessel wall
• Platelets
• Coagulation factors

Question 19

What are 2 types of Coagulative Disorders

Answer 19

Congenital and acquired

Question 20

Identify 3 congenital coagulation factor disorders

Identify 3 acquired coagulation factor disorders

Answer 20

Haemophilia A ( Deficiency in factor 8)
Haemophilia B (Deficiency in factor 9)
Von Willebrand’s disease

Liver disease
Vit K deficiency (Causes more bleeding)
Anticoagulants

Question 21

Identify 4 signs of Coagulation factor disorders

Answer 21

• Intercerebral haemorrhage
• Severe post op, post traumatic bleeding
• Joint pain and deformity
• Prolonged bleeding after dental extraction

Question 22

What is the inheritance pattern for Haemophilia
How does it present
How is it treated

Answer 22

X-linked recessive

Bleeding into muscles and joints, and post-operatively

Treated with recombinant factor 8 or DDAVP (releases factor 8 from vessels)

Question 23

What is the inheritance pattern for Von Willebrand’s Disease

Identify 2 signs

What is the main genetic defect

Answer 23

Autosomal dominant

• Abnormal platelet adhesion to vessel wall
• Reduced Factor 8 amount/ activity

Main: Reduced vWF production

Question 24

What are 3 clinical signs of von Willebrand’s Disease

Answer 24

Skin and mucous membrane bleeding

Prolonged bleeding after trauma

Spontaneous joint/ muscle bleeds (Rare)

Question 25

Name 2 vessel wall abnormalities | Where do these occur

Answer 25

Easy bruising Spontaneous bleeding from small vessels Mainly skin but can be from mucous membranes

Question 26

How does Disseminated Intravascular Coagulopathy affect; PT APTT Fibrinogen count D dimer count What must happen for DIC to occur

Answer 26

Raised PT Raised APTT Low fibrinogen Raised D dimers Must be a trigger

Question 27

Identify 5 triggers for DIC

Answer 27

``` Malignancy Massive tissue Injury Infections Massive haemorrhage and transfusion ABO transfusion reaction ```

Question 28

What are Thrombophilias How common are these? Do patients with these develop clots

Answer 28

Acquired/ congenital defects of haemostasis Rare conditions, not unless patients have additional risk factors

Question 29

What are the Congenital and Acquired causes of Thrombophilias

Answer 29

Congenital causes include deficiency in Natural Anticoagulants and an Abnormal Factor 5 Acquired causes include Antiphospholipid syndrome