SECRETION AND REABSORPTION (Continued) QUANTIFYING REABSORPTION AND SECRETION One means of assessing the secretion or reabsorption profile of a particular solute is to examine its changing concentration along the length…
Because of the countercurrent multiplier system, there is a strong gradient for water reabsorption from the collecting duct that increases in strength toward the papillae. Because water reabsorption is a…
Descending Thin Limb. The descending thin limb reabsorbs an additional fraction of the filtered water. There is a large gradient for water reabsorption from this segment even though it reabsorbs…
RENAL HANDLING OF POTASSIUM Potassium is a primarily intracellular ion, with skeletal muscle alone containing more than 75% of the body’s total load. Less than 2% of this load is…
RENAL HANDLING OF CALCIUM, PHOSPHATE, AND MAGNESIUM CALCIUM More than 98% of total body calcium is in bones, whereas the remainder is located in intracellular and extracellular fluid. Normal plasma…
COUNTERCURRENT MULTIPLICATION (Continued) Once deposited in the interstitium, some urea drifts from the inner medulla and is secreted back into the proximal tubule and loop of Henle. By reentering the…
RENAL HANDLING OF SODIUM AND CHLORIDE (Continued) Because of this system, an increase or decrease in total body sodium will lead, by necessity, to expansion or contraction of the ECF…
RENAL HANDLING OF SODIUM AND CHLORIDE (Continued) Thick Ascending Limb. In this segment, sodium, chloride, and potassium undergo transcellular reabsorption together on an apical cotransporter (NKCC2). Two chloride ions are…
COUNTERCURRENT MULTIPLICATION (Continued) In Panel 4, steady state has been reached, meaning that no additional solute is being added to the system. Thus the incoming and outgoing fluid are iso-osmotic….
COUNTERCURRENT MULTIPLICATION The countercurrent multiplier system is a sophisticate apparatus that evolved in mammals and birds to con serve water. It forms a longitudinal concentration gradient in the medullary interstitium…
