Hypernatremia is described as the hallmark of dehydration and triggers which part of the nervous system?

• A. Cardiovascular System
• B. Central Nervous System
• C. Respiratory System
• D. Digestive System

Answer: (B)

Hypernatremia reflects high plasma osmolality from water loss, and the brain is especially sensitive to osmotic shifts. Osmoreceptors in the hypothalamus detect this rise and initiate the thirst drive and the release of antidiuretic hormone, all coordinated within the central nervous system. This CNS involvement means brain cells can become dehydrated as water moves out of them, leading to neurologic symptoms such as confusion or seizures. Thus, the part of the nervous system triggered here is the central nervous system.