70 PHYSIOLOGY CHAP. 



a pleasant sensation as the stomach becomes filled by food. 

 But if the satisfaction of the want is delayed the unpleasant 

 sensation increases, and spreads from the epigastrium to the 

 surrounding parts, until sensations of constriction, cramp, and 

 strain are produced throughout the abdominal walls, and located 

 specially in the stomach, oesophagus, pharynx, floor of the mouth, 

 soft palate, parotid region, masticatory muscles, temples, and 

 epicranial aponeurosis, where it assumes the diffuse form of dull 

 headache. In other words, hunger is a complex sensation in 

 which all the organs that function during alimentation and 

 digestion participate more or less distinctly. The discomfort in 

 the epigastric region arising from the cardiac orifice or from the 

 whole stomach is the fundamental feeling in hunger, to which 

 are subsequently added the accessory feelings that come from 

 other parts of the digestive system as a whole and the associated 

 organs and tissues. 



All conditions that stimulate general metabolism and increase 

 the loss from the organism such as muscular exercise, cold air, 

 mountain climate, sea air, convalescence after fever, or the early 

 stages of growth accentuate the sensations of hunger, which 

 under these conditions becomes proportional to the need of 

 compensation, restoration of the loss, and development of the 

 tissues. All conditions that retard metabolism and diminish loss 

 produce the opposite effect ; such are the summer season, sedentary 

 habits, complete muscular inactivity, old age, narcotics (opium, 

 tobacco, cocaine, alcohol). 



Under abnormal conditions hunger may reach a morbid level, 

 clinically known as bulimia. In this case hunger sets in again 

 1-2 hours after a meal, and if not satisfied may rapidly produce 

 intense pains in the stomach, dimness of vision, agitation, delirium, 

 fainting. All these symptoms subside after a full meal. 



There are also morbid perversions of the sense of hunger, in 

 which appetite for things that are not eatable and are even dis- 

 gusting, such as earth, clay, ash, coal, straw, hair, and excrement, 

 may be developed. 



In most acute febrile diseases, although there is tissue- waste 

 and progressive emaciation, there is also loss of appetite (anorexia), 

 and hunger may be replaced by repugnance to food of even the 

 most delicate and tempting kinds, which is due not to abolition 

 but to perversion of the sense of taste. In smokers the acquired 

 need to smoke disappears along with the sense of hunger. 



Anorexia is not uncommon in hysterical patients, and in 

 predisposed subjects it may be suggested during hypnosis. In 

 the insane sitiophobia (repulsion to food) is frequent, but is then 

 due to delusions and not to absence of the sensation of hunger. 



Even in sane people an intense moral emotion, e.g. bad news, 

 drives away the feeling of hunger. If the attentio'n is keenly 



