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).
There are many theories behind why we age, and one is the hormone theory of aging. Learn more about how hormones might affect the aging process. There are many theories behind why we age, and one is the hormone theory of aging. Experts who back this idea believe hormones, which control the function of organs, could be behind agingâand maybe even the fountain of youth. Learn more about how hormones might be the culprit behind the aging process.