164 ANATOMY AND PHYSIOLOGY 



four and one-half minutes. The thought of distasteful food 

 inhibits the flow of gastric juice, as do nauseous flavors and odors. 



Clinical note. The sense of distaste diminishes the flow of gastric juice, 

 therefore it would seem wise to avoid forcing a patient to take more than 

 the minimum necessary quantity of food while the distaste is marked. 



Pepsin is sensitive to alkalies. Alkalies and malts may favor 

 a flow of gastric juice, but if given during digestion, they destroy 

 the pepsin. 



Proteins always soften when treated with water, and become 

 transparent before they can be dissolved; salty foods do not easily 

 soften they are not easily digested. This is the reason why it 

 is well to precede the cooking of dry and salty foods by soaking 

 in water. 



The presence of ordinary fat delays digestion in the stomach, 

 although a very finely divided fat, as in cream or the yolk of 

 egg, may be there partially digested by a ferment called gastric 

 steapsin. 



An accumulation of stomach contents is embarrassing to the 

 gastric juice, hence the advisability of deliberation when taking 

 one's meals. 



Note. Hemoglobin is split by pepsin into hematin and a globin. The 

 hematin gives the dark color to the blood which is vomited after gas- 

 tric hemorrhage, and also to that which appears in feces after intestinal 

 hemorrhage. (Hemoglobin is contained in the red cells of the blood.) 



The passage of food through the intestine is normally slow, and 

 thus it is fully exposed to the surfaces of the circular folds of the 

 mucous membrane. By the absorption of digested food the intes- 

 tinal contents are diminished in quantity and changed in character, 

 containing less water and approaching a firmer consistency. After 

 passing through the ileo-colic sphincter into the large intestine 

 there is little but waste remaining, undigested food forming the 

 major portion. This collection of waste, liquids, coloring matter 

 and undigested food is called feces. The coloring matter is derived 

 partly from bile, partly from food. (It may be modified by drugs ; 

 for example, iron and bismuth give a black color to the feces.) 

 (The odor is due to sulphuretted hydrogen and to skatol it also is 

 modified by food.) The consistency depends upon the amounts of 

 water and mucus, approaching a liquid form when the intestinal 



