fluid-electrolyte physio 2 Flashcards
how is water balance sensed
osmoreceptor in hypothalomus
how does osmoreceptor work
shrinks and grows in response to tonicity
what are 2 ADH receptors
v1 - vasoconstriction
v2 - antidiuretic
2 stim for ADH release
- high ECF osmolatiry
2. low eff. art volume
how does ADH work
insertion of aquaporin channel into CCD and MCD
3 stims. for water intake
- habitual, social
- thirst via hypernatremia
- thirst via hypovolemia
2 response to low free water
- thirst to incr. water intake
2. ADH up to hold onto water
what is free water
water without Na
how much free water in 1L of [70] Na
0.5L free water and 0.5L [140]
2 potential causes of hypernatremia
- too much Na in ECF - drank saltwater
2. too little water in ECF - reduced intake or high loss
what is diabetes insipidus
lack of and ADH effect
2 types of diabetes insipidus
- central - pit/hypo impaired release
2. nephrogenic - kidney doesn’t repsond
what is acute and adaptive cell change to hypernatremia
acute: cells shrink and pull away
adaptive; brain imports new K particles to adapt
how to treat hypernatremia
- treat cause
2. give free water
how to give free water
by mouth if can
how to give IV free water
- D5W
2. 50 normal saline
what is ECF vol in hyponatremia
could be high low or normal
what is expected response to hyponat.
osmoreceptor drops ADH - excrete free water
4 possible causes of hyponat.
- ADH present when it should be supressed
- vast intake
- advanced renal failure
- reduced delvery of filtrate to ALOH
2 possible reasons for ADH to be present despite hyponatremia
- effective art, volume depletion - baroreceptor action via hypovolemia
- non-volume stim for ADH - disease or drug
what is acute and adaptive cell change to hyponatremia
acute: cells swell and give cerebral edema
adaptive: cells export particles and return to nromals
