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Animation: Control of Water Reabsorption

by Pearson
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Hormones regulate water reabsorption by the nephron tubule in response to body fluid intake and loss. On a hot day, when you are sweaty and thirsty, blood solute concentration rises. In response, the brain signals the posterior pituitary to increase its output of the hormone ADH. ADH makes the walls of the collecting duct more permeable to water. Recall that the interstitial fluid surrounding the nephron tubule has a high solute concentration. ADH allows more water to leave the filtrate by osmosis and reenter the blood. The body conserves water and concentrated urine is produced. When you have been drinking more water and not losing much fluid, the blood becomes more dilute. The brain responds by decreasing the secretion of ADH. The collecting duct becomes less permeable, and less water is reabsorbed. The body produces dilute urine.
Hormones regulate water reabsorption by the nephron tubule in response to body fluid intake and loss. On a hot day, when you are sweaty and thirsty, blood solute concentration rises. In response, the brain signals the posterior pituitary to increase its output of the hormone ADH. ADH makes the walls of the collecting duct more permeable to water. Recall that the interstitial fluid surrounding the nephron tubule has a high solute concentration. ADH allows more water to leave the filtrate by osmosis and reenter the blood. The body conserves water and concentrated urine is produced. When you have been drinking more water and not losing much fluid, the blood becomes more dilute. The brain responds by decreasing the secretion of ADH. The collecting duct becomes less permeable, and less water is reabsorbed. The body produces dilute urine.