The brain and kidneys regulate the amount of water excreted by the body. When the blood volume is low, the concentration of solutes in the blood is high. When the hypothalamus senses this low blood volume and increased serum osmolality it synthesizes ADH, a small peptide molecule. The pituitary gland then releases ADH into the bloodstream and causes the kidneys to retain water by concentrating the urine and reducing urine volume. Water retention boosts blood volume and decreases serum osmolality.
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Date last modified: July 25, 2011.
VCU School of Nursing