Appetite

a pleasant sensation associated with the need for food; also, a physiological mechanism regulating the intake of food substances into the organism. After long deprivation of food, appetite becomes the sensation of hunger.

Appetite is closely related to the activity of the feeding center, primarily those parts of the feeding center located in the hypothalamus and in the cortex of the cerebral hemispheres. Appetite is determined by information coming to the feeding center about nutritive conditions, the intake and assimilation of food, and the consumption of food reserves. Appetite is not caused by the exhaustion of the organism’s food reserves; rather, appetite gives warning beforehand of the exhaustion of food reserves, so that the many stimuli that make up the appetite can change their signals in accordance with a change in the dietary regimen. Stimulation of the appetite depends on the amount of products of intermediary metabolism in the blood, the level of assimilation of these products by the cells, the amount of water in the tissues, the condition of the fat reserves, the contraction of the empty stomach, the lowering of body temperature, and the many external stimuli associated with conditioned reflex activity (the appearance and odor of food, habitual surroundings, and others). Inhibition of the appetite results from eating, distension of the walls of the stomach by food, absorption and assimilation of the products of digestion, and change in the hormonal balance.

General appetite, that is, appetite for any food, is distinguished from specialized or selective forms of appetite which reflect the organism’s need for proteins, fats, carbohydrates, mineral substances, and vitamins. Appetite makes possible the regulation of the need for specific foods in quantities required by the organism. It also promotes the digestion and assimilation of food by stimulating the secretion of saliva and gastric juices. A good appetite is often a sign of physical and mental well-being. Disorders of the appetite are symptomatic of many diseases. A decrease in appetite (anorexia), a pathological increase in appetite (bulimia), or perverted appetite may be found in cases of brain tumors, many nervous and psychological disorders, diseases of the digestive tract, avitaminosis, and endocrine diseases. Normalization of appetite depends on treatment of the basic disease and observance of the proper dietary regimen.