renal physiology

PCT & DCT cells secrete ----------- hydrogen ion

	Substances absorbed	Substances secreted
PCT	Water Urea Sodium Potassium Chloride Bicarbonate Uric acid Glucose Phosphate Amino acids	H+ Acids & bases PAH NH4+ Diodrast
Loop of Henle	Water Urea Sodium Potassium Chloride Calcium Magnesium
DCT	Water Urea Sodium Potassium Chloride Bicarbonate Phosphate	H+ K+ NH4+ Uric acid
Collecting duct	Water Urea Sodium Potassium Chloride

The concentration of urine produced is directly proportional to

§  Length of loop of henle

§  Thickness of medulla relative to cortex

Na+

§  65% of filtered sodium is reabsorbed in PCT

§  25% in loop of henle

§  4% in DCT

§  3% in late distal tubule & collecting duct  

Bicarbonate

§  85% absorbed in PCT

§  10% thick ascendimg limb

§  5% -------------- DCT & colletcing duct

H+ secretion

§  85% ------- PCT

§  10% ----------thick ascendimg limb

§  5%------------  DCT & colletcing duct

 Handling of solutes by kidney

		Relative concentration
Creatinine	Not resorbed Secreted in small amounts	GF≈urine
Uric acid	90% is first absorbed in PCT but later secreted in DCT	GF≈Urine
Urea	About 40% reabasorbed in PCT	GF>urine
Sodium	Partially reabsorbed	GF> urine
Glucose	Completely reabsorbed	GF>> urine
Amino acid	Completely reabsorbed	GF>> urine