Receive:

• Filtrate of varying osmolality

Process:

• Minimal Na+ and K+ reabsorption
• H2O reabsorption.

Produce:

• Aldosterone: steroid hormone that acts to increase Na+ reabsorption. At the same time it enhances K+ and H+ secretion.
• Vasopressin (ADH):
• • Brings aquaporins to the apical surface
  • Makes collecting ducts permeable to water, otherwise water reabsorption is very low

Export:

• Urine of varying osmolality