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

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)

Age-related thermoregulation hinges on how heat is produced and conserved, and how the body controls blood flow to the skin. Infants have a large surface area relative to their mass, which means they lose heat to the environment more readily. Their shivering response is immature and less efficient, so they cannot generate heat as effectively. In contrast, elderly individuals often have diminished autonomic control of blood vessels (reduced ability to vasoconstrict to conserve heat) and reduced sweating capacity, which together impair heat retention and the ability to adjust heat loss, increasing their risk of hypothermia in cold conditions. The other statements don’t fit known physiology: infants do not have a lower surface area-to-mass ratio, and they do not have enhanced vasomotor control in old age; adults generally regulate heat more effectively than both infants and the elderly; and age does affect thermoregulation.

Age-related thermoregulation hinges on how heat is produced and conserved, and how the body controls blood flow to the skin. Infants have a large surface area relative to their mass, which means they lose heat to the environment more readily. Their shivering response is immature and less efficient, so they cannot generate heat as effectively. In contrast, elderly individuals often have diminished autonomic control of blood vessels (reduced ability to vasoconstrict to conserve heat) and reduced sweating capacity, which together impair heat retention and the ability to adjust heat loss, increasing their risk of hypothermia in cold conditions.

The other statements don’t fit known physiology: infants do not have a lower surface area-to-mass ratio, and they do not have enhanced vasomotor control in old age; adults generally regulate heat more effectively than both infants and the elderly; and age does affect thermoregulation.