What process does an infant use to generate heat and maintain core temperature during cold stress?

An infant generates heat and maintains core temperature during cold stress primarily through a process known as nonshivering thermogenesis. This process is especially important in newborns due to their high surface area-to-volume ratio, which makes them more susceptible to heat loss.

Nonshivering thermogenesis occurs in brown adipose tissue, which is present in significant amounts in neonates. When exposed to cold, the body activates this brown fat, which generates heat through metabolic processes. The activation of brown adipose tissue in response to cold stress is essential for infants, who lack the ability to shiver effectively as a means of thermoregulation, unlike older children and adults.

This mechanism not only helps in maintaining the infant's core body temperature but also plays a critical role in ensuring optimal organ function and overall metabolic activity during periods of cold exposure. Consequently, nonshivering thermogenesis allows the infant to produce heat in a way that is energy efficient and critical for survival in the early stages of life.