24 APPLIED PHYSIOLOGY 



the sides of the intestine into the liquid food. Peptone 

 and sugar easily soak into these blood tubes, and are car- 

 ried to the liver. There the liver cells change the peptone 

 back to a form of albumin much like that which was eaten. 

 It is then fit food for the cells, and is sent to all parts of 

 the body with the blood. The liver cells also change the 

 sugar to a kind of starch. This is soon oxidized in the 

 liver, and heat is produced for the use of the body. 



Fat is soaked up by another set of tubes called lacteals. 

 The lacteals begin in the villi, and finally empty the fat 

 into a blood tube in the neck. The fat is then carried to 

 the lungs, where it is oxidized so as to produce heat for 

 the body. 



35. Action of the bowels. As the food slowly passes 

 down the intestine, its liquid parts soak into the blood 

 tubes, so that by the time it reaches the large intestine 

 most of its water and all its useful parts have been removed, 

 and only waste matter is left, which is driven on and out 

 of the body. These waste matters should be expelled 

 regularly at least once a day. If it is done at a certain 

 time, the intestine will form the habit of always acting at 

 that time. If the waste matters are not given off, we have 

 headaches, and may become sick, for they poison the body. 



36. Use of the liver. If poisons are swallowed, they 

 too are taken up by the blood tubes, and are carried to the 

 liver. The liver cells strive to keep these poisons from 

 going farther along the blood tubes, and thus they protect 

 the body against bad food. So the liver has very impor- 

 tant uses. When it gets out of order, it sends but little 

 bile to digest the food. It lets poisons from the intestine 

 pass by, and does not change the digested food to a form 

 suited to the cells of the body. The result is a kind of 

 sickness called biliousness. 



