Human Phys 1.6 Flashcards
What happens when you add isotonic NaCl to ECF?
No osmosis, no change in ICF, increase in ECF
What happens when you add hypertonic NaCl to ECF?
Osmosis of water from ICF to ECF, increase in osmolarity in ICF and ECF, increase in ECF volume but decrease in ICF volume (because Osmolarity is higher in EFC)
What happens when you add hypotonic NaCl to ECF?
Decreased osmolarity in both, increased ICF volume (due to osmosis) and increased ECF volume (due to addition of solution)
(Osmolarity is higher in ICF)
Na+ accounts for what percentage of ECF?
90%
What is the normal range for Na+?
135-145 mEq/L
Hyponatremia
Na+<135 mEq/L
What can Hyponatremia be caused by?
Diarrhea
Vomiting
Diuretic overuse
Increased water retention (SIADH)
What are the consequences of hyponatremia?
Causes symptoms like headache and alters nerve and muscle action potentials which may cause twitching or weakness
How can Hyponatremia be treated?
By creating an osmotic gradient across the BBB (mannitol can create the osmotic gradient and pull water out of brain tissue)
What do glial cells do in the brain?
Reduce intracellular osmolytes to minimize cell swelling
What happens if disturbed water is balanced too quickly and we already have reduced intracellular osmolytes?
Glial cells shrink and die
What do glial cells synthesize?
Myelin (essential for proper nerve conduction)
What are the effects of osmotic demyelination syndrome?
Irreversible (usually affects the pons)
What is the most common electrolyte disorder in clinical practice?
Hyponatremia (15-25%)
Who is at the greatest risk for hyponatremia?
Elderly (contributes to cognitive deficits)
