HUNGER AND APPETITE 



509 



after a bismuth meal, and which have been thought by clinical observers 

 to indicate a hyperperistalsis of the stomach. The fundus is therefore 

 not entirely passive during digestion; for, although early in this act 

 there may be no evidence of contraction, yet the contractions of the tonus 

 rhythm may appear and become pronounced before the stomach is en- 

 tirely empty. In other words, the digestion contractions of the filled 

 stomach (see page 485) pass gradually over into the hunger contractions 

 of the empty organ. 



Remote Effects of Hunger Contractions. It is well known that during 

 hunger certain general subjective symptoms are likely to be experienced, 

 such as a feeling of weakness and a sense of emptiness, with a tendency to 

 headache and sometimes even nausea in persons who are prone to headache 

 as a result of toxemic conditions. Headache is likely to be more pronounced 

 or perhaps present only in the morning before there is any food in the stom- 

 ach. These symptoms indicate that hunger contractions are associated with 



Fig. 169. Showing augmentation of the knee-jerk (upper tracing) during the marked hunger con- 

 tractions (lower tracing). (From Carlson.) 



hyperexcitability of the central nervous system, and it is of considerable 

 interest that objective signs of this association can be elicited. If the 

 knee-jerk be recorded along with a record of the gastric contractions, it 

 will be found that it is markedly exaggerated simultaneously with the 

 strong hunger contractions of the empty stomach, this augmentation 

 being greatest at the height of the stomach contractions, when the hun- 

 ger pangs are most intense, and falling off again to normal when these 

 disappear (Fig. 169). Further changes occurring during the hunger 

 period include an increase in the pulse rate and vasodilatation. By 

 comparing plethysmographic tracings of the arm volume (see page 209) 

 and stomach contractions, it has been found that the increase in volume 

 occurs pari passu with the increasing tonus of the stomach, but that it 

 begins to shrink before the stomach contraction has reached its maximum. 

 Occasionally, however, as in acute hunger, a somewhat different rela- 



