5.4.2 Circulatory Disturbances 2

Question 1

What is haemostasis?

Answer 1

Localised interaction between endothelium, platelets, coagulation factors, to cease bloodloss

Question 2

What are the five stages of haemostasis?

Answer 2

1 - Transient vasoconstriction
2 - Primary haemostasis: platelet aggregation and platelet plug
3 - Secondary haemostasis: fibrin platelet aggregation
4 - Concurrent thrombosis/fibrinolysis
5 - Tissue repair

Question 3

What is a haemorrhage? What are the two types?

Answer 3

Extravasation of erythrocytes into the extravascular space.

Rhexis - vessel wall disruption
Diapedesis - blood vessel wall allows BRCs to escape

Question 4

What causes a decrease in platelets (thrombocytopenia)?

Answer 4

↓ production
↑ destruction
↑ use

Question 5

What are the 7 causes of haemorrhage (diapedesis)?

Answer 5

1 - endothelial injury
2 - Immune Mediates Disease
3 - Developmental collagen disorders
4 - Collagen defects in guinea pigs and primates deficient in Vit C
5 - Thrombocytopaenia
6 - Thrombocytopathy
7 - Reduced conc. of coagulation factors

Question 6

What may cause Thrombocytopathy?

Answer 6

Inability to adhere/aggregate to injury site
Inherited defects
Von Willebrand’s disease

Question 7

What causes a decrease in conc or function of coagulation factors (CFs)?

Answer 7

Inherited deficiencies of Cfs
↓ production
↓ production of Vit K dependant CFs
↑ use of CFs

Question 8

What is Petchaie?

Answer 8

Pin point 1-2mm hemorrhages in the skin, mucous membrane, serosal surfaces

Question 9

What is Petchaie?

Answer 9

Pinpoint 1-2mm hemorrhages in the skin, mucous membrane, serosal surfaces

Question 10

What is Eccymoses?

Answer 10

Larger (2-3cm) hemorrhages with more extensive damage

Question 11

What is Suffusive haemorrhage?

Answer 11

Large continuous areas of haemorrhage

Question 12

What is a thrombosis?

Answer 12

Formation of excessive/inappropriate clot on endothelium of blood/lymphatic vessel or in heart

Question 13

What is an embolus?

Answer 13

Particulate matter travels within the vascular system. Can lodge and cause obstruction of small vessels > infarction (tissue death)

Question 14

What is a thromboemboli?

Answer 14

Emboli derived from fragments of a thrombosis.

Question 15

What is infarction?

Answer 15

Area of peracute ischemia that undergoes coagulative necrosis (following occlusion of blood vessels)

Question 16

What can cause abnormal blood flow?

Answer 16

• Local stasis or ↓ blood flow
• Cardiac disease
• Aneurysm
• Hypovolaemia

Question 17

What does abnormal blood flow cause?

Answer 17

• Endothelial injury / dysfunction
• Allows platelet to more readily interact with endothelium
• Prevent dilution of activated clotting factors by fresh flowing blood + inflow of inhibitors
• Turbulence allows interaction between coagulation factors

Question 18

What causes hypercoagulability?

Answer 18

• Inflammation
• ↑ platelet activity
• ↑ clotting factor activation
• Anti-thrombin III deficiency

Question 19

Describe the appearance of an arterial thrombi

Answer 19

• Initiated by endothelial damage
• Red/grey/ pale
• firmly attached
• Lamintaed
• Tails extending downstream

Question 20

Describe the appearance of a venous thrombi

Answer 20

• Often areas of stasis
• Dark red, gelatinous, soft
• Occlusive, moulded to vessel wall
• Extend upstream
• loose attachement

Question 21

Describe the fate of a thrombus (5)

Answer 21

Dissolution
Propagation
Organisation
Recanalisation
Embolisation