Control of ECF and Osmolality II Flashcards
Change in plasma osmolality (change in Na intake/output) cause or acute change in water intake or output
increase or decreased water reabsorption to correct osmolality
Changes in ECF volume and BP cause
excretion or reabsorption of Na
Main effectors of ECF volume
SNS, RAAS, ANP, ADH, pressure-naturiesis
High ECF volumes result in
increased GFR, decreased Na reabsorption, increased water excretion
Low ECF volumes
decreased GFR, increased Na reabsorption, and increased water retention
Edema is the accumulation of fluid in the interstitial space
Caused by the capillary filtrate coefficient, which increases when venous pressure increases (R side HF or liver disease)
If fluid is accumulating in the interstitium then the circulating volume decreases this is detected and
low volume senses would cause retention of Na and Water to increase circulating volume
pressure-naturiesis
is the most POWERFUL controller of ECF volume and long term BP, DIRECT effect of increased MAP and Na excretion
Pressure-naturiesis and chronic hypertension
the relationship is shifted to the right
Decreased TPR and stabilized, followed by increased MAP and TPR and BP what happened
Na excretion immediately went up with pressure, and Na excretion and H2O caused decreased ECF fluid and stabilized at low ECF volume
Alterations to pressure-naturiesis curve shift or slope
to a higher BP at same Na intake (chronic hypertension)
DASH diet (fruit and vegetables) decreases BP
shifts the pressure-naturiesis to the LEFT at a lower BP
Hyperaldosteronism
hypertension, increased ECF volume, NORMAL Na excretion (NA balance) and not edemic
Continued aldosterone only retains Na and H2O to an extent and then intake = output, WHY?
pressure-natriuresis allows kidney to ESCAPE from high levels of aldosterone, if arterial pressure isn’t recognized by the kidney the Na excretion will continue to respond to aldosterone
