MOD Session 5- Haemostasis And Thrombosis

Question 0

What is the key step in the coagulation cascade?

Answer 0

Prothrombin=> thrombin
Thrombin causes
Fibrinogen=> fibrin.

Question 1

Define haemostasis

Answer 1

The body’s response to prevent blood loss and stop bleeding

Question 2

What is the main step in the fibrinolytic system?

Answer 2

Plasminogen=> plasmin via plasminogen activators

Plasmin breaks down fibrin.

Question 3

2 examples of fibrinolytic therapies

Answer 3

Streptokinase

tPA

Question 4

Why is streptokinase a fibrinolytic therapy?

Answer 4

It activates plasminogen.

Question 5

Define thrombosis

Answer 5

The formation of a solid mass of blood within he circulatory system.

Question 6

What is Virchow’s triad?

Answer 6

States that Thrombosis occurs due to:

• vessel wall abnormalities
• blood flow abnormalities
• blood component abnormalities

Question 7

Give an example of a blood vessel wall abnormality

Answer 7

Atheroma, direct injury, inflammation

Question 8

Given an example of a blood flow abnormality

Answer 8

Stagnation, turbulence

Question 9

Give an example of why a blood component abnormality arises

Answer 9

Smokers, post-op, pregnancy

Question 10

Define embolism

Answer 10

The blockage of a blood vessel by a solid, liquid or gas, at a site distant from its site of origin.

Question 11

What are the 5 types of emboli?

Answer 11

• nitrogen
• amniotic fluid
• air
• medical equipment
• tumour cells

Question 12

What are the predisposing factors of DVT? (7)

Answer 12

• oral contraceptives
• trauma and severe burns
• pregnancy
• IMMOBILITY
• disseminated cancer
• post op
• cardiac failure

Question 13

Why is a massive pulmonary embolism (PE) rapidly fatal?

Answer 13

Causes more than 60% blood flow reduction.

Question 14

What is given to prevent DVT?

Answer 14

Subcutaneous heparin

Stockings

Question 15

What is the treatment for DVT?

Answer 15

Intravenous heparin

Oral warfarin

Question 16

What are the four necessary components for successful haemostasis?

Answer 16

• constriction of blood vessels in the vessel wall
• platelets adhere to each other and the damaged vessel wall to form a plug.
• coagulation system- cascade that converts prothrombin to thrombin, which in turn converts fibrinogen to fibrin.
• fibrinolytic system- activates plasmin through conversion of plasminogen to plasmin, is in turn causes the break down of fibrin.

Question 17

Give two examples of thrombin inhibitors. What happens if you have a deficiency in them?

Answer 17

Anti thrombin III
Protein C/S
Thrombosis of thrombophilia can result.

Question 18

Describe the appearance of a venous thrombus. (3)

Answer 18

Dark red, soft and has a high cell content

Question 19

Describe the appearance of an arterial thrombus. (3)

Answer 19

Pale, granular and has a low cell content.

Question 20

What are the five outcomes of thrombosis?

Answer 20

1. Lysis- breakdown of the thrombus completely.
2. Propagation- spread of the thrombus
3. Organisation- a reparative process in which fibroblasts and capillaries invade, but the obstruction remains.
4. Re canalisation- at least one channels forms through the organising thrombus, but blood flow restoration is only partial.
5. Embolism- part of the thrombus breaks off and travels and lodges at a distant site.