Global Brain Activity Flashcards
Most important electrolyte influencing the brain:
- sodium
- potassium has significant peripheral
presence hence will affect the heart
which will affect the brain - calcium, magnesium and phosphate
Sodium and the Brain:
- major osmotically active solute in
ECF - hyper>145mmol/L
- hypo<135mmol/L
Acute Hyponatremia:
- low level of sodium outside of the
cells - water will move into the cells
- cells swell leading to cerebral
oedema - decreased blood flow
- cerebral compression
to compensate:
- will shift CSF into systemic circulation
- then will push K+ out of cells to make
water follow
- release of osmolytes like
glutamine,mate, taurine
Chronic hyponatremia:
may be asymptomatic due to the adaptations
Cerebral Oedema: Symptoms:
- nausea
- vomiting
- anorexia
- headaches
- lethargy
- disorientation
- muscle cramps
Cerebral Oedema: Signs:
- seizures
- coma
- hyporeflexia
- respiratory depression
- hypothermia
What is shown below?
Areas of herniarion
Central Pontine Myelinolysis (osmotic demyelination syndrome)
- result of rapid overcorrection of low
sodium in ECF - in cases of chronic hyponatremia
(asymptomatic) (swollen cells) - slow correction needed to prevent
fluid shift damaging cells - demyelination due to death of
oligodendrocytes
shrink cells by adding sodium or restricting fluid intake
Hypernatremia:
- too much sodium in ECF
- water will move into the ECF
- cells shrink
- haemorrhage from veins and
arteries due to tearing
Compensation:
- uptake of potassium into cells
- uptake of osmolytes into cells
(glutamine,mate,taurine)
- ^^^protective against cell damage
overcorrection can cause cerebral oedema
hyponatremia
hypernatremia
insert diagram
Acid-Base Disorders:
- acidemia = <7.35
- alkalosis = >7.45
- CO2 can cross the BBB easily
- CO2 regulates cerebral blood flow
- compensatory metabolic correction
when there is a chnage in CO2
(ventilation) - hyperventilation in resp alkalosis:
less CO2 reduces cerebral blood flowlightheadedness, syncope, seizures,
hypocalcaemia - hypoventilation in resp acidosis: too
much CO2, increase cerebral blood
flow, increases pressuremorning headaches, visual
disturbances and confusion
As CO2 increases, effect on cerebral blood flow?
increases till plateau
Acid-base disorder:
other electrolyte disturbances
CAT Diagrams:
