ABSTRACT
This chapter introduces the biology of growing old. It discusses the changes in physiological effectiveness with increasing age, and examines the scope for modifying these changes. The chapter also discusses some of the mechanisms of ageing. Osteoporosis has characteristic features that separate it from other forms of bone disease. In simple terms, a person with osteoporosis has a lower bone mass than might be expected from age and sex norms, and an increased risk of fracture. In skeletal muscle there is a general reduction in muscle mass with increasing age, partly due to cell death and partly atrophic change. Atrophy is most likely due to inactivity. The functional implications of age-related changes in the structure and function of the central nervous system are immense. Age-associated changes in neurotransmitter chemicals of the nervous system may be responsible for the failure to integrate functions properly in old age.
