222 



ELEMENTS OF PHYSIOLOGY 



described. The digested starch (glucose) and digested cane 

 sugar (glucose) and the digested proteids (peptones) pass 

 into loops of the blood vessels contained in the tiny projec- 

 tions called villi, and are carried to the liver. Both the 

 small amount of these substances which is absorbed by 

 the stomach, and the large amount which is absorbed 

 from the small intestine, are taken by means of a system 

 of veins called the portal circulation (Fig. 178), to the 

 liver, where they may be stored or may pass through 

 the liver and vena cava to the general circulation. The 

 mineral substances, iron, lime, sulphur, and phosphates are 

 contained in the proteid food and are digested and ab- 

 sorbed with it. Water and salt do not require digestion. 

 It was formerly believed that the food 

 passes into the lacteals and capillaries 

 strictly according to the physical law of 

 osmosis which governs the passage of 

 fluids through dead membranes. It is 

 now believed that the epithelial cells lin- 

 , ing the canal take up the food and give it 

 into the absorbent vessels by a process 

 resembling secretion ; but osmosis aids 



FIG. 176. -The Valve the PrOCCSS. 



between the Large 395. The Large Intestine or Colon 



and Small Intestine. (p . ^ {& ^^ fiye ^ 1()ng ^ 



a, small intestine; e, large 



intestine; d, c, valve; walls are drawn into pouches, or puckers, 

 6, appendix. ^y bands of muscles running lengthwise 



along it. The small intestine joins it in the lower part of 

 the abdomen on the right side (Fig. 176). The junction is 

 not at the end of the large intestine but above the end. 

 The part below the junction is called the c&cum. Attached 

 to the ccecum is a small tube called the vermiform appendix. 

 Above the juncture the large intestine is called the colon.. 

 The ascending colon runs up along the right side nearly 

 to the waist. It is then called the transverse colon, and it 



