Physiology Flashcards
Anaerobic threshold and age?
Falls by 10-20% between 60-80yrs old
what is the AT ?
The VO2 at which there is an imbalance between lactate production and elimination.
CO2 significantly increases
What is the optimum AT ?
AT > 11ml/kg/min
What are the causes of secondary brain injury?
hypercarbia, hypoxia, hypotension, hypoglycaemia and hyperglycaemia
What is the most important factor regulating cerebral vascular tone?
Carbondioxide
Increase in cerebral blood flow ?
There is a linear increase between 20-80mmHg
Cerebral blood flow does not significantly change until PO2 falls below?
50mmHg or 6.5kPa - Below this, CBF increases
Features of Conn’s syndrome or primary hyperaldosteronism?
- Hypokalaemia
- Alkalosis
- Low renin
- Hypertension
- Muscles weakness & tetany
Causes of primary hyperaldosteronism?
- Adrenal adenoma
- Bilateral adrenal hyperplasia
Classification of cerebral ischaemia?
- Complete or incomplete
- Global or focal
At what cerebral blood flow does EEG changes begin to appear?
30-40ml/100g/min
Normal cerebral blood flow?
54ml/100g/min
Characteristics of incomplete ischaemia?
- Reduced CBF
- Anaerobic metabolism of glucose
- Reduction in the removal of waste product
- Acidosis
- Lactataemia at CBF < 20ml/100g/min
- At 10-20ml/100g/min - Free radicals
- Evoked potentials vanish at 10-20ml
- < 10ml/100g/min irreversible brain injury
- Cerebral oedema
What are the causes of cholinergic crisis in patients with MG?
- ## Overdose with anticholinesterase inhibitor
What are the effects Acetylcholine at the muscarinic & nicotinic receptor?
acetylcholine at muscarinic receptors causing stimulation at effector organs sites (abdominal colic, sweating, miosis and lacrimation).
In addition, nicotinic receptors at neuromuscular junctions are also stimulated causing muscle weakness and fasciculation.
