18 HUMAN PHYSIOLOGY. 



FOOD. 



A Food may be defined to be any substance capable of playing a part 

 in the nutrition of the body. 



Food is required for the repair of the waste of the tissues consequent on 

 their functional activity, for the generation of heat and the evolution of force. 



Hunger and Thirst are sensations which indicate the necessity for 

 taking food ; they arise in the tissues at large, and are referred to the 

 stomach and fauces, respectively, through the sympathetic nervous system. 



Inanition or Starvation results from an insufficiency or absence of 

 food, the physiological effects of which are hunger, intense thirst, intestinal 

 uneasiness, weakness and emaciation ; the quantity of carbonic acid ex- 

 haled diminishes and the urine is lessened in amount ; the volume of the 

 blood diminishes; a fetid odor is exhaled from the body; vertigo, stupor 

 followed by delirium, and at times convulsions, result from a disturbance 

 of the nerve centres; a marked fall of the bodily temperature occurs, from 

 a diminished activity of the nutritive process. Death usually takes place, 

 from exhaustion. 



During starvation the loss of different tissues, before death occurs, aver- 

 ages T %, or 40 per cent, of their weight. 



Those tissues which lose more than 40 per cent, are fat, 93.3 ; blood, 75 ; 

 spleen, 71.4; pancreas, 64.1; liver. 52; heart, 44.8; intestines, 42.4; 

 muscles, 42.3. Those which lose less than 40 per cent, are the muscular 

 coat of the stomach, 39.7 ; pharynx and oesophagus, 34.2 ; skin, 33.3 ; 

 kidneys, 31.9; respiratory apparatus, 22.2; bones, 16.7; eyes, 10; nervous 

 system, 1.9. 



The Fat entirely disappears, with the exception of a small quantity 

 which remains in the posterior portion of the orbits and around the kid- 

 neys. The Blood diminishes in volume and loses its nutritive properties. 

 The Muscles undergo a marked diminution in volume and become soft and 

 flabby. The Nervous system is last to suffer, not more than two per cent, 

 disappearing before death occurs. 



The appearances presented by the body after death from starvation are 

 those of anaemia and great emaciation ; almost total absence of fat ; blood- 

 lessness ; a diminution in the volume of the organs; an empty condition 

 of the stomach and bowels, the coats of which are thin and transparent. 

 There is a marked disposition of the body to undergo decomposition, 

 giving rise to a very fetid odor. 



The duration of life after a complete deprivation of food varies from 

 eight to thirteen days, though life can be maintained much longer if a 



