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Renal Regulation of Extracellular Fluid Volume and Osmolality - Download article and take CE posttest
Lori Candela and Carolyn Yucha

In order for our body cells to function properly, they must be surrounded in extracellular fluid that is relatively constant with regard to osmolality. The kidneys, in concert with neural and endocrine input, regulate the volume and osmolality of the extracellular fluid by altering the amount of sodium and water excreted. This is accomplished primarily through alterations in sodium and water reabsorption, the mechanisms of which differ within each nephron segment.

Goal:
Discuss the mechanism by which the kidney integrates signals from other body systems to control extracellular fluid volume and osmolality.

Objective:

1. Describe the mechanisms by which sodium and water input and output are controlled.
2. Outline the neurological and endocrine effects on sodium and water homeostasis.
3. Compare and contrast the mechanisms for sodium, chloride and water transport in the proximal tubule, the thick ascending limb and the collecting duct.