Читать книгу Disorders of Fluid and Electrolyte Metabolism - Группа авторов - Страница 19

Plasma tonicity, the number of effective osmoles in a kilogram of plasma water, is one of the homeostatic mechanisms narrowly guarded by the kidneys. The importance of tonicity homeostasis is linked to the control of cell volume as under hypertonic conditions cells shrink and under hypotonic conditions cells swell. In acute hypotonic disorders, the swelling leads to cerebral edema with devastating and life threatening neurologic consequences.

Tonicity homeostasis is intimately linked to the kidney’s control of water excretion in the face of great variations in water intake. This chapter reviews the process that allows for constancy of plasma tonicity in the face of variations in water intake and the consequences that result from a failure to respond to such changes.