Lab 6- Renal Explanations and Expectations

what are the expectations for the hypotonic subject?

increased GFR/creatinine clearance, decrease specific gravity and Na+ clearance, slight increase in pH, increase in flow rate

what are the expectations for the isotonic subject?

increase in GFR/creatinine clearance, Na+ clearance and flow rate, no change/increase in specific gravity

what are the expectations for the alkalotic subject?

slight increase in specific gravity and sodium clearance, no change in flow rate or GFR, increase in pH

why does sodium clearance decrease in the hypotonic subject?

decrease in blood osmolality causes decrease in ADH secretion, producing very dilute urine and reabsorbing sodium to compensate for fluid load

why does sodium clearance say steady in the isotonic subject?

load is not an osmotic challenge so rate of sodium reabsorption/excretion is steady

why is there minimal changes in sodium clearance in the alkalotic subject?

concentrated solution, but small volume

why does specific gravity decrease in the hypotonic subject?

increased water excretion due to water volume load

why does specific gravity stay relatively stable in isotonic subject?

no osmotic challenge so rate of sodium and water reabsorption and excretion stays steady

why might specific gravity slightly increase in alkalotic subject?

slightly concentrated urine, but small volume

why does GFR increase in the hypotonic and isotonic subjects?

due to volume overload/increased ECF volume

explain the mechanism behind why GFR increases in hypotonic and isotonic subjects

increased secretion of ANP (detects stretching from volume overload) --> decreases Na+ reabsorption (and thus water too) at DCT and CD --> increased dilute urine volume

increased aldosterone secretion --> decreased water reabsorption in DCT and CD --> increased dilute urine volume

why does pH increase in the alkalotic subject?

bicarbonate in solution; type B intercalated cells excrete bicarbonate and potassium and reabsorb H+, increasing pH

how do the kidneys compensate when a subject vomits?

HCl is the major component of concern; loss of gastric H+ induces metabolic alkalosis, so kidneys increase secretion of bicarbonate and reabsorption of H+ to compensate

define water diuresis

increased urination of large, dilute volumes of urine with little/no increase in solutes

what is diuresis in response to?

excess water ingestion but also inappropriate vasopressin secretion

what are some substances that induce diuresis?

caffeine: inhibits ADH release

diuretics: increase sodium secretion to induce osmotic diuresis