Final answer:
Infants and the elderly are most susceptible to thermoregulation problems due to underdeveloped or declining homeostatic balance, respectively. Body size and composition, as well as gender differences in metabolic rate, also affect an individual's ability to regulate body temperature in response to environmental conditions.
Step-by-step explanation:
In infants, their thermoregulatory systems are not yet fully developed, which leaves them at greater risk for conditions associated with extremes of temperature, such as hypothermia and heat stress. On the other hand, the normal aging process is associated with a decline in homeostatic balance and a reduction in the physiological capacity to adapt to temperature changes. This reduction can lead to increased susceptibility to -hyperthermia (overheating) and hypothermia (overcooling), particularly in extreme temperatures. Additionally, elderly people are more vulnerable to certain diseases because their bodies have a harder time fighting off infections, and they may have a more challenging time regulating body temperature due to weakened homeostatic functions.
Susceptibilities to temperature-related issues can also vary based on body size and composition. For instance, individuals with less body fat may be more susceptible to cold temperatures, while those with greater muscle mass may have a higher basal metabolic rate, affecting their ability to generate heat internally. In terms of gender differences, men generally have more muscle mass and thus may have a higher metabolic rate than women, indicating variations in how each gender might experience and handle temperature extremes.