ABSTRACT
Together with the nervous system, the endocrine system coordinates homeostatic responses to environmental signals for the protection of the individual organism and regulates reproductive functions for the perpetuation of the species. With aging, the main expressions of declining functional competence are as follows:
• Cessation of reproduction in women • Diminishing capacity to adapt to external
demands, especially under stress conditions (Chapters 1 and 3)
Observations of changes in physiologic competence with aging have been related, since the end of the 19
century, to endocrine deficiency because of the broad range of hormonal actions, many of them necessary for reproduction and survival, and because of the possibility of restoration of “vitality” and “well-being” by hormonal replacement therapy. At early and late stages of the life
span, development and aging affect endocrine function and, in turn, are affected by hormonal changes. It is unclear if aging of key endocrine systems is the cause or the consequence of the cellular and molecular changes responsible for senescence and death; nevertheless, it is evident that hormonal manipulations may influence functional decrements, disabilities, diseases of old age, and length of the life span. Previous reviews of the aging of endocrines have been presented in earlier editions of this book
and in several endocrinology texts.
