Rapid Review

Activities in Various Parts of the Nephron

Part	Activity
Bowman's capsule	Filtration of blood
Proximal tubule	Reabsorption (active transport) of glucose, amino acids, Ca2+, other electrolytes. Secretion of H+, K+, NH3, creatine, organic acids.
Descending loop	Diffusion of water and electrolytes
Ascending loop	Active reabsorption of Cl- (Na+ follows passively). Counter-current sytem establishes high osmotic pressure in medulla.
Distal tubule	Active reabsorption of Na+ (Cl- follows passively). Secretion of H+, K+, NH3.
Collecting duct	reabsoption of water by osmosis (ADH-dependent). Secretion of H+, K+, NH3.