CHAPTER IX 

 INTESTINAL DIGESTION 



Physiological anatomy of the small intestine Mucous membrane Intestinal juice Action 

 of the intestinal juice in digestion Pancreatic juice Internal secretion by the pancreas 

 Composition and properties of the pancreatic juice Action of the pancreatic juice on 

 carbohydrates Action of the pancreatic juice on proteids Action of the pancreatic juice 

 on fats Action of bile in digestion Movements of the small intestine Physiological 

 anatomy of the large intestine Ileo-csecal valve Peritoneal coat Muscular coat 

 Mucous coat Processes of fermentation in the intestinal canal Contents of the large 

 intestine Stercorin Indol, scatol, phenol, cresol etc. Movements of the large intes- 

 tine Defecation Gases found in the alimentary canal. 



PHYSIOLOGICAL ANATOMY OF THE SMALL INTESTINE 



THE small intestine, extending from the pyloric opening of the 

 stomach to the ileo-caecal valve, is loosely held to the spinal column by 

 the mesentery. As the peritoneum lining the cavity of the abdomen 

 passes from either side to the spinal column, it comes together in a 

 double fold in front of the great vessels along the spine, and passing 

 forward, divides again into two layers, which become continuous with 

 each other and enclose the intestine, forming its external coat. The 

 width of the mesentery usually is three to four inches (7.62 to 10. 16 

 centimeters) ; but at the beginning and at the end of the small intestine, 

 it abruptly becomes shorter, binding the duodenum and that portion of 

 the intestine which opens into the caput coli closely to the subjacent 

 parts. The. mesentery thus keeps the intestine in place, but it allows a 

 certain degree of motion, so that the tube may become convoluted, ac- 

 commodating itself to the size and form of the abdominal cavity. The 

 form of these convolutions is irregular and is constantly changing. The 

 length of the small intestine, according to Gray, is about twenty-five 

 feet (7.6 meters) ; ljut the canal is very distensible, and its dimensions 

 are subject to frequent variations. Its average diameter is about an inch 

 and a quarter (3.18 centimeters). 



The small intestine is divided into three portions, which present 

 anatomical and physiological peculiarities more or less marked. These 

 are the duodenum, the jejunum and the ileum. 



The duodenum has received its name from the fact that it is about 

 the length of the breadth of twelve fingers, or eight to ten inches 



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