ABSORPTION OF FOOD L73 



Oxygen is breathed in from the air, and the various Baits, 

 such as common salt, sodium chloride (so'di-um kld'rid, or 

 rid), calcium (kal'si-um), magnesium (lnag-nf-'/.hi-um, or 

 -shi-),jP0ta$8iM??i(po-tas'si-um), and phosphorus (fos'fBr-US ) 

 are taken in with our food. They are useful to the body. 

 A small amount of iron is also contained in food and water 

 and becomes a part of the red blood cells. 



LABORATORY STUDY 



Study food and food tests. Artificial gastric juice is easily prepared 

 "by taking | gram of pepsin, T a ff cc. of strong hydrochloric (hi-drft-klo'- 

 rik) acid and adding 50 cc. of water. Take white of egg that has been 

 cooked and subject it, in a test tube, to the above mixture. A variety of 

 tests should be made, with and without heat (100 F.) with and without 

 the acid. Pancreatic juice is made by uniting 15 grains sodium (so'dl-fim) 

 carbonate (kar'bon-at), 5 grams pancreatin (pan'kiv-a-tin), and 100 cc. 

 water. The action of this fluid may be tested as above on the fata, as 

 ■olive oil ; on starch, as flour ; and on proteins, as raw lean meat or milk. 

 Also examine several of the common articles of food to determine to what 

 •class of foodstuffs they belong. 



147. Absorption of Food. — The absorption of food in man 

 .and animals is the process of taking the digested foods 

 from the alimentary canal into the blood. Practically no 

 food is absorbed in the mouth or esophagus, and but little 

 in the stomach. 



The absorption of food from the intestinal canal is 

 done by small folds in the lining of the small intestine. 

 To the naked eye, these folds appear as a covering of 

 minute hairs, called villi (villi). Their structure is shown 

 in Figure 189. 



The process of osmosis, which has been so frequently 

 referred to in Part I, is the chief factor in the passing of 

 the food into the blood vessels. This process is assisted by 

 the action of the livinsr cells in a manner not well under- 

 stood. 



