278 DIGESTION, CIRCULATION, AND ABSORPTION 



Here may be also found the beginnings of other small tubes 

 that carry emulsified fats and oils to a vein under the left collar 



bone. These small 

 tubes are called lymph 

 capillaries. As they 

 carry emulsified fats 

 and oils (for a time 

 after meals) they are 

 milky colored and are 

 thus called lacteals 

 (lac = milk). 



Conclusion. Show 

 how the villi may be 

 said to " lick up the di- 

 gested food." 



b. How Foods are 

 Absorbed 



1 Foods 

 into the 



are absorbed 



FIG. 62. Diagram of the structure of a block mtO trie blood vessels 



of tissue smaller than a pin's head, cut from an d lacteals of the villi 



the wall of the small intestine, a, mouths Qf the intestina l tract, 1 

 of intestinal glands ; 6, villus cut lengthwise 



to show the blood capillaries and white lacteal and get into 



within ; e, lacteal vessel sending branches to latioil in the following 



many villi ; i, intestinal glands ; m, artery ; wavs . 



v, vein ; I and t, mus'cular coats. . ^ 



1. Osmosis. ii-x- 



Where have you 



change through a moist membrane, 

 heard of this before ? 



2,. Filtration. Forced through by pressure when the mus- 

 cular walls of the intestine contract. 



3. Imbibition. About as a sponge absorbs water, or as a 

 towel does the same. 



i Nine tenths of the food that reaches the blood is absorbed by the villi 

 of the small intestine. There are fully 20,000 villi to the square inch. 



