Final answer:
Decreased physiological reserve in the elderly refers to their reduced capacity to adapt to stress, due to a variety of changes such as a decreased basal metabolic rate, osteoporosis, and decreased intestinal peristalsis.
Step-by-step explanation:
In the elderly population, decreased physiological reserve refers to the reduced capacity to adapt to stress. This is a result of various physical and cognitive changes that occur as people age. The physiological reserves in various systems, be it the immune system, cardiovascular system, or the body's metabolism, start to diminish as part of the aging process.
For instance, elderly individuals may experience a decreased basal metabolic rate, loss of muscle mass (which contributes to a decrease in strength), and changes in bone density that may lead to conditions like osteoporosis. Additionally, the digestive system may slow down, seen as decreased intestinal peristalsis, which can affect nutrition and overall health. Cardiovascular changes also occur, such as weakened heart muscle, which affects the heart's pumping efficiency.
Therefore, when faced with physiological stress—be it an illness, extreme temperatures, or even the demands of exercise—the elderly may not respond or adapt as effectively as younger individuals, due to these reduced physiological reserves.