Chapter 4 – THERMOREGULATION IN YOUNG MAMMALS

Publisher Summary This chapter discusses the thermoregulatory abilities of young mammals. It discusses thermoregulatory mechanisms of young mammals differ from, or resemble, those of adults. The thermoregulatory capacities of all mammals whether young or old are limited by their thermal insulation and the area of the exposed surface; the smaller the mammal the greater is the exposed surface relative to its body weight. These two factors obviously impose limits on the maximum and minimum size of mammals living in different climates if they are to achieve homeothermy. Only the larger mammals can live on earth's surface in arctic climates. Smaller mammals would be immobilized by the fur necessary to retain their body heat. Although many newborn mammals are relatively helpless, the physiological mechanisms that control their internal environment are neither poorly developed nor ineffectual, though they are often different from those that operate in adults. In some respects, newborn mammals tolerate changes in environmental conditions better than adults; for example, they withstand hypoxia and trauma and hypothermia better and with less general disturbance and less permanent damage. Physiological mechanisms in newborn mammals are mature, and it may be misleading to view them as stages in the development of mechanisms, which are present in adults. Indeed, newborn mammals have some abilities that they subsequently loose.