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).
Wear and tear theories of biological aging propose that aging in humans and other animals is simply the result of universal deteriorative processes that operate in any organized system.tochastic theories of aging similarly. propose that aging is the result of inevitable small random changes that accumulate with time. Entropy, in this context, refers to the tendency of all matter to decay into a. more random, less ordered state.