Our organs and metabolic processes function most efficiently at about 37 degrees Celsius. The normal body temperature can ranged between 35.5 and 40 degrees Celcius. We employ a number of mechanisms to maintain our temperatures within that normal range.
Some thermoregulatory mechanisms are voluntary others are involuntary. Putting on a sweater or seeking shade are examples of voluntary mechanisms. Shivering and peripheral vasodilation are examples of involuntary mechanisms.
The hypothalamus is the control center for thermoregulation. It receives input from thermal receptors throughout the body. Stimulation of the anterior hypothalamus yields vasodilatation and sweating. Stimulation of the posterior hypothalamus causes shivering.
Elderly people are at high risk for developing potentially life-threatening disturbances of temperature regulation due to normal age-related changes. For example, it takes an elderly person nearly twice the time it takes a younger person to return to normal core body temperature after exposure to temperature extremes.
Diminished ability to thermoregulate is evident at about age 70 and worsens with each decade of life. Thirst, blood vessel dilation or constriction, and the ability to perspire are normal homeostatic mechanisms that help individuals regulate body temperature during extremes of cold or heat. Due to changes in sweat glands that occur with age, older people experience a progressive decrease in their ability to perspire. Decreased subcutaneous fat deposition often places elderly persons at particular risk for increased heat loss.