The areas of the tongue sensitive to tastes. The classical theory about the physiology of taste recognizes the existence of four fundamental tastes - sweet, salty, sour and bitter - each being perceived by specific areas of the tongue by means of gustatory receptors, also known as taste buds.
Theories of Aging. Theories of Aging. Erik Erikson, who took a special interest in this final stage of life, concluded that the primary psychosocial task of late adulthood (65 and beyond) is to maintain ego integrity (holding on to one's sense of wholeness), while avoiding despair (fearing there is too little time to begin a new life course).
1 Such as the 'wear and tear' theory where body tissue becomes worn from use and cannot continuously renew itself. 2  The rate-of-living theory suggests that rapid expenditure of energy precipitates early aging and slow expenditure results in slower aging.rogrammed Cellular Aging Theory. 1  Suggests that aging may be a result of an impairment of the cell in translating necessary RNAs as a result of increased turnoffs of DNA. 2  In other words, the transcription of these messages into functional proteins may be restricted in older people.