680 



PHYSIOLOGY 



reflexly with the beginning of the act of deglutition. When a second act 

 of deglutition succeeds the first with a sufficiently short interval, the reflex 

 inhibition due to the second act may prevent the development of any wave 

 of contraction in the oesophagus. This tube thus remains in a lax condition 



FIG. 334. Curves obtained during swallowing by placing two rubber balloons, one 

 (the upper curve) in the pharynx, the other (lower curve) in the oesophagus. 

 In A the second balloon was 4 cm. ; in B 12 cm. ; and in c 16 cm. from 

 the upper end of the oesophagus. In each curve ifr will be noticed that the 

 excursion of the upper lever is followed immediately by an excursion of the 

 lower lever (due to passage of the swallowed fluid and transmitted rise of 

 pressure), and then, after an interval of time varying with the distance between 

 the balloons, by another rise due to the peristaltic contraction of the wall of 

 the oesophagus. 



and allows the free rapid passage of the food downwards until the movements 

 of deglutition have come to an end, when a peristaltic contraction occurs and 

 sweeps all remaining adherent particles of food into the stomach. The 

 circular fibres of the lower end of the oesophagus which form the cardiac 

 sphincter of the stomach are normally in a state of tonic contraction. When 

 one mouthful of food is swallowed it may be either squirted directly into the 

 stomach, or may remain at the lower end of the oesophagus until the following 



