circulatory disturbances

Question 1

Define oedema

Answer 1

Excessive extracellular fluid in the intertitial fluid space

Question 2

Mechanisms by which Oedema may occur? List

Answer 2

1. Increased hydrostatic pressure
2. Decreased plasma oncotic pressure- reduced protein
3. Lymphatic obstruction
4. Increased vascular permeability
5. Sodium retention- can raise hydrostatic pressure eg renal failure

Question 3

Describe the gross appearance of an oedema

Answer 3

Wet, swollen, fluid oozing from cut surfaces. Fluid may be yellow and may clot. Affected tissue may be firm yet doughy.

Question 4

What 3 components does haemostasis rely on?

Answer 4

Platelets, endothelium and coagulation cascade

Question 5

What is a thrombus?

Answer 5

A clot. And Thrombosis is the formation of a clot within the CVS

Question 6

How do you distinguish a thrombus from a post mortem clot? (grossly)

Answer 6

Thrombus

• Firm
• Attached to vessel wall
• Dull and rough if arterial and moist and gelatinous if venous
• grey and red if arterial, red plus laminations if venous

Post mortem clot

• Rubbery
• Not attached to vessel wall
• Always moist and smooth
• All red or yellow and red ‘chicken clots’

Question 7

What happens in an injury to the endothelial cells which cause blood clotting (thrombus)?

Answer 7

Exposes the subendothelial cells to flowing blood which are reactive for clotting. This can occur due to trauma, toxaemia, inflammation, metabolic disorders.

Question 8

Define infarction

Answer 8

Obstruction of the blood supply to an organ. Can be due to thrombus or emboli and this causes local death of tissue

Question 9

What is the major mediator of fibronolysis?

Answer 9

Plasmin.

Question 10

Define Ischimia

Answer 10

An inadequate blood supply to an organ or part of the body, especially the heart muscles

Question 11

What are the causes of thrombosis?

Answer 11

1- Endothelial damage caused by a trauma for example which consequently exposes flowing blood to sub-endothelial tissues causing clotting.

2-Disrupted blood flow sue to turbulence (no lamia flow) or stasis (blockage). This brings platelets with close contact to the endothelial cells and causes coagulation eg DVT

3- Hypercoagulability. In dogs this can be due to deficiency in antithrombin III.

Question 12

What are the outcomes of thrombosis?

Answer 12

• Resolution due to fibrinolysis
• Organisation and recanalisation
• Embolism
• Infarctions