Cell Pathology 2 Flashcards
What is oedema?
Abnormal increase in interstitial fluid
What maintains interstitial fluid balance?
- Hydrostatic pressure (determined by BP)
2. Osmotic pressure (maintained by solutes in blood and interstitial fluid)
Give 5 causes of oedema?
- Increased hydrostatic pressure.
- Salt & H2O retention
- Reduced plasma osmotic pressure
- Lymphatic obstruction
- Inflammation
What is generalised oedema?
Widespread fluid accumulation in subcutaneous tissues and serous cavities
Name 1 factor for generalised oedema?
Renin-angiotensin-aldosterone pathway
What is seen in the skin of patients with generalised oedema?
Pitting
List the causes of generalised oedema.
- LV failure
- Nephrotic syndrome (kidney damage)
- Hepatic failure
What causes pulmonary oedema?
Raised hydrostatic pressure in the pulmonary capillary bed.
What is the most common cause of pulmonary oedema?
LV failure
How can LV failure cause pulmonary oedema?
- Inadequate removal of blood from pulmonary circulation.
- Pressure builds up in pulmonary circulation.
- Fluid accumulates in alveolar interstitium. Eventually moves into alveolar space - poor gas exchange.
What is the main symptom of pulmonary oedema?
Breathlessness (dyspnoea), usually worse when lying flat (orthopnoea).
Why is one more susceptible to pneumonia if they have pulmonary oedema?
Fluid in the alveolar space predisposes the lungs to bacterial infection.
What causes cerebral oedema?
- Disruption of blood flow to cerebral capillaries
2. Causes pressure buildup in blood vessels.
Where is cerebral oedema seen?
In brain tissue surrounding lesions
Give 4 lesions in the brain
Contusion, haemorrhages, infarcts (stroke) and tumours.
Increase in fluid in the brain causes what.
- Increased inter cranial pressure.
2. High ICP increases risk of herniation and death.
How should cerebral oedema be treated?
- Raise the head (allows gravity to drain fluid).
- Infuse isotonic fluids (replenish lost fluid from blood)
- Infuse steroids and osmotic diuretics (Eg mannitol) - gets fluid back into blood
- Surgical decompression
What is a thrombosis?
Abnormal blood clot formation in the circulation
What are the 3 factors that cause thromboses?
- Blood stasis
- Vessel wall injury
- Hypercoagulability
What are the main factors in venous thrombosis?
Stasis and hyper coagulability.
Why do most venous thromboses occur in deep leg veins?
- Blood may be hyper coagulable.
- Venous BP is much lower than arterial BP.
- Therefore blood may stop flowing, especially in legs (as working against gravity).
- In periods of non-movement, thromboses may occur (as muscle contraction in legs are major factor for pushing blood back upto heart).
What is the main cause of arterial thromboses?
Atherosclerotic plaque, which causes vessel wall injury.
What is the most important potential complication of a VT.
Pulmonary embolism.
How can an Arterial thrombosis cause ischaemia or Infarction?
Arterial wall narrows (stenosis), because thrombus blocks the wall.