132 



DIGESTION AND ABSORPTION 



.-^11 blaclcler 



.. bile cUict 

 from liver 



cJommon 



Common // 

 bile cmal; 

 |xxn&reoti& 



III. Mount a drop of the emulsified oil under the microscope. 



A. Describe the difference in the appearance of the two drops of oil. 



B. Why would you expect emulsification to hasten the digestion of fats ? 



IV. Bile and succus entericus are alkaline liquids. What effect would you 

 expect them to have on the digestion of fat ? 



The liver. The liver is the largest gland in the body. It is 

 situated on the right side of the body, and covers part of the 



stomach, small intestine, 

 and large intestine. The 

 upper surface fits closely 

 into the under surface 

 of the diaphragm. The 

 liver secretes an alkaline 

 juice, yellowish-green or 

 brown in color, called 

 bile. This pours, by 

 means of the bile duct, 

 into the small intestine 

 only during the period 

 of digestion. The alkali 

 in the bile activates the 

 digestion of fats and helps in the absorption of digested fats. The 

 excess bile passes through another duct into the bile sac or gall 

 bladder, where it is stored until needed. Sometimes a part of 

 the bile substance crystallizes in this duct, forming gallstones. 

 In such a case, the bile duct is closed and the excess bile passes 

 into the blood, causing jaundice. 



Intestinal digestion. The presence of food in the small intes- 

 tine stimulates the flow of intestinal juice which contains a num- 

 ber of enzymes. An intestinal protease, erepsiuy helps to convert 

 the proteoses and peptones formed in the stomach into the end 

 products of digestion, amino-acids. Several inverting enzymes 

 in the intestinal juice convert the double sugars into single or 



small intestine; 



Not far below the stomach, a tube empties into the 

 intestine. This tube leads from the pancreas, the liver, 

 and the gall bladder, and drains juices into the intestine. 



