Page 1041 - Fundamentals of anatomy physiology

Spotlight Figure 26–16
Summary of Renal Function

300 mOsm/L

1 H2O

The filtrate produced by the 300
renal corpuscle has the same
osmotic concentration as Nutrients 300 H2O 300
plasma—about 300 mOsm/L. Ions
It has the same composition RENAL CORTEX 300
as blood plasma but does not
contain plasma proteins. 600 H2O 600 600
600
2
RENAL MEDULLA H2O 900 900
In the proximal convoluted H2O Nephron
tubule (PCT), the active removal Vasa loop
of ions and organic nutrients recta
produces a continuous osmotic 900
flow of water out of the tubular
fluid. This decreases the volume
of filtrate but keeps the solutions
inside and outside the tubule
isotonic. Between 60 and 70
percent of the filtrate volume
is absorbed here.

3

In the PCT and descending
limb of the nephron loop, water
moves into the surrounding
peritubular fluids, leaving a
small volume of highly concen-
trated tubular fluid. This reduc-
tion occurs by obligatory water
reabsorption.

KEY = Water = Impermeable H2O 1200
A reabsorption to solutes 1200

= Variable water = Impermeable 1200
reabsorption to water
1200
= Na+/Cl– = Variable permeability
transport to water

= Aldosterone- 300 = Fluid osmotic
regulated pump concentration (mOsm/L)

= Solutes

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