| 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. |
