Which statement best describes age-related differences in thermoregulation for infants, adults, and elderly?

• A. Infants have lower surface area-to-mass ratio than adults, greater heat loss risk; elderly have enhanced vasomotor control
• B. Infants have higher surface area-to-mass and less efficient shivering; elderly have reduced vasomotor control and sweating capacity, increasing susceptibility to hypothermia
• C. Adults have the highest risk of hypothermia due to flexible vasomotor control
• D. Age does not affect thermoregulation

Answer: (B)

Thermoregulation depends on balancing heat production with heat loss, and how this balance is altered by age-related anatomy and autonomic control. Infants lose heat quickly because their surface area relative to body mass is high, so warm objects are more exposed to their skin. They also have immature shivering responses, making heat generation less efficient when they’re cold. In contrast, elderly individuals often have blunted autonomic control of skin blood vessels and fewer functioning sweat glands, which dampens both heat retention and dissipation. This reduced vasomotor and sudomotor function means they’re slower to conserve heat in the cold and slower to dissipate heat when it’s hot, increasing their risk of hypothermia in cold environments.

So the statement that infants show a high surface area-to-mass ratio with greater susceptibility to heat loss and limited shivering, while the elderly show diminished vasomotor control and sweating capacity, best reflects how thermoregulation changes across age. It captures why the youngest are prone to rapid heat loss and why older adults have impaired mechanisms to adjust temperature, making them more vulnerable to temperature-related stress.