Function of the kidney:
1-Excretory:excretion of waste products& drugs
2-Regulatory:control of body fluids volume & composition.
3-EndocrinalFunction kidney tongue.pngroduction of erythropoietin,renin& P.G.
4-Metabolic:metabolism of vit.D.

Endocrine function of the kidney:
-Renin –Angiotensin system.
-Production of P.G & erythropoietin.
-It’s a site of action of ANP.
-Vit.D metabolism.
-It’s the site of action of parathhormone.

1-P.C.T.

-reabsorption of Na, K, H2O glucose, A.A. , Po4, HCO3,
-excretion of H+












2-Loop of Henle

-reabsorption of Na, Cl, Ca, K in A.
limb and reabsorption of H2O in D. limb
-it increases the medullary tonicity which
is important in the process of urine
concentration in collecting tubule
as follow:
·Na outflow from ascending
limb ­ Na in medulla

­ medullary tonicity?
·AD Hr. open H2O channels of collecting tub. through C.A.M.P.

Subject fluid in collecting tub.
To high medullary tonicity.

H2O reabsorption Urine conc.



3-Distal tub.

Na reabsorption & k excretion through aldosterone.
Also there reabsorption of H2O from distal nephron and excretion of H.
4-Collecting tubulesconcentration of urine as above


Source: Internal Medicine Book of Dr.Osama Mahmoud (Ain Shams University)