Water and Osmolality Controls

Principal transport processes in the renal nephron. ADH, Antidiuretic hormone. [Reproduced with permission from M. B. Burg, The nephron in transport of sodium, amino acids, and glucose. Hasp. Pmct. 13(10), 99 (1978). 

Amino acid sequence of atrial natriuretic peptide. It has a one-disulfide linkage. 

The pH of extracellular fluid is kept within very narrow limits (7.35-7.45) by buffering mechanisms (see also Chapter 1), the lungs, and the kidneys. These three systems do not act independently. For example, in acute blood loss release of ADH and aldosterone restores the blood volume and renal regulation of the pH leads to shifts in K+ and Na+ levels. 

Despite considerable variation in fluid intake, an individual maintains water balance and a constant composition of body fluids. The homeostatic regulation of water is 

CHAPTER39 Water, Electrolytes, and Acid-Base Balance 

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