After age 50, which physiological change occurs?

After age 50, which physiological change occurs?

• A. Thirst sensitivity decreases and urine-concentrating ability decreases
• B. Thirst sensitivity increases
• C. Urine-concentrating ability increases
• D. There is no change

Answer: (A)

As people age, the body’s regulation of fluid balance becomes less efficient, particularly in two areas: the drive to drink and the kidney’s ability to concentrate urine. Thirst sensation tends to decline because the brain’s osmoreceptors and signaling pathways become less responsive, so older adults may not feel thirsty even when they need fluids. At the same time, the kidneys lose some concentrating power due to fewer functioning nephrons, a less robust medullary gradient, and reduced responsiveness to antidiuretic hormone. The result is a decreased ability to concentrate urine and a blunted thirst drive, which helps explain why the statement that thirst sensitivity decreases and urine-concentrating ability decreases is correct. The other options contradict these well-established aging changes, and saying there’s no change ignores these common physiological shifts.

As people age, the body’s regulation of fluid balance becomes less efficient, particularly in two areas: the drive to drink and the kidney’s ability to concentrate urine. Thirst sensation tends to decline because the brain’s osmoreceptors and signaling pathways become less responsive, so older adults may not feel thirsty even when they need fluids. At the same time, the kidneys lose some concentrating power due to fewer functioning nephrons, a less robust medullary gradient, and reduced responsiveness to antidiuretic hormone. The result is a decreased ability to concentrate urine and a blunted thirst drive, which helps explain why the statement that thirst sensitivity decreases and urine-concentrating ability decreases is correct. The other options contradict these well-established aging changes, and saying there’s no change ignores these common physiological shifts.