Page 166 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Inulin clearance = glomerular filtration rate (GFR)

Inulin
Filtration and Clearance

Amount excreted/time = Amount filtered/time
= =
Urinary inulin concentration = Plasma inulin concentration
H 2 O . (urine volume/time) . (filtered volume/time)
·
Urinary inulin U ln (g/L) . VU (mL/min) = P ln (g/L) . GFR (mL/min) Glomerular
concentration No reabsorption
rises due to H 2 O No secretion
reabsorption GFR = U ln . . VU (mL/min)
P ln
GFR ≈ ca. 120mL/min Plate 7.3
per 1.73m body surface area
2

B. Clearance levels (1) lower or (2) higher than inulin clearance
Glucose Organic anions or
Amino acids cations (e.g. PAH and
Na , Cl etc. atropine, resp.)
–
+

1 2
Filtration Filtration
+ +
Reabsorption Secretion

Low High
excretion rate excretion rate

C X C X Fractional C X C X Fractional
= = = FE <1.0 = = = FE >1.0
C ln GFR excretion C ln GFR excretion 153
SD7.3
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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