VOMITING 133 



4. Fats are liberated by the proteolytic digestion of 

 their fibrous envelopes, and are to some extent hydrolysed 

 by the gastric lipase. 



5. Cane sugar is inverted to dextrose and Isevulose. 



6. In the early stage of digestion bacteria taken in with 

 food decompose carbohydrates with formation of lactic 

 acid. 



7. These bacteria are destroyed by the HCl. 



The Hydrochloric acid performs the following functions — 



1. It activates pepsinogen and is necessary for the 

 proteolytic action of pepsin. 



2. It inverts cane sugar. 



3. It destroys bacteria. 



4. It maintains the closure of the cardiac sphincter. 



5. It stimulates the stomach to peristaltic contraction. 



6. It governs the opening and closing of the pylorus. 



7. As we shall see later, it is necessary for the activation 

 of the pancreas. 



Vomiting 



Vomiting is a reflex action induced by irritation of the 

 stomach or of certain other parts of the body, particularly 

 the ahmentary canal. It may also be excited by irritation 

 of the brain, as in tumours, or by emotions. It is usually 

 preceded by a free flow of saliva, which is swallowed. 

 Then come retching movements, which are really attempts 

 at inspiration with the glottis closed. These culminate 

 in the actual vomiting, which is a co-ordinated muscular 

 act. The stomach is compressed by the simultaneous 

 contraction of the diaphragm and the abdominal muscles. 

 At the same time its walls undergo contraction. The 

 gastric contents are thus driven out through the cardiac 

 orifice, which is dilated. 



When vomiting is violent, antiperistalsis of the small 

 intestine may occur, driAdng the intestinal contents into 

 the stomach. 



