This instructional module on physiological aspects of aging is one in a block of 10 modules designed to provide the human services worker who works with older adults with basic information regarding the aging process. An introduction provides an overview of the module content. A listing of general objectives follows. Nine sections present informative material on each of the nine objectives. Topics are: the physiology of aging; changes in the skin and in the musculoskeletal, cardiovascular, respiratory, gastrointestinal, urinary, and central nervous systems; and sexuality changes. Other contents include a summary and listings of selected readings and additional resources. (YLB)