416 THE HUMAN BODY 



stomach. Its right end is the larger, and is embraced by the 

 duodenum (Fig. 135), which there makes a curve to the left. A 

 duct traverses the gland and joins the common bile-duct close to 

 its intestinal opening. The pancreas produces a watery-looking 

 secretion which is of great importance in digestion; the gland also 

 secretes a hormone which exerts an important influence on the 

 general nutritional processes of the Body (Chap. XXX). 



The Blood- Vessels of Alimentary Canal, Liver, Spleen, and Pan- 

 creas. The portal vein (Vp, Fig. 135) has already been referred 

 to as differing from all other veins in that it not only receives blood 

 from a system of capillaries but ends in a second set of capillaries, 

 which lie in the liver. The quantity of blood brought to supply the 

 hepatic capillaries by the hepatic artery is in fact much less than 

 that brought by the portal vein. The stomach, the intestines, the 

 pancreas, and the spleen are supplied with arterial blood from three 

 great branches of the aorta. The most anterior of these, the celiac 

 axis, springs from the aorta close beneath the diaphragm and 

 divides into the hepatic artery, splenic artery, and arteries for the 

 stomach; some of these divisions may be seen in Fig. 135. The 

 pancreas is supplied partly from the hepatic, partly from the 

 splenic artery. The two other branches (superior and inferior 

 mesenteric artery) are given off from the aorta lower down in the 

 abdominal cavity; the former (5, Fig. 135) supplies the small in- 

 testine and half of the large, the latter the remainder.of the large. 

 The blood passing through all these arteries becomes venous in the 

 capillaries of the organs they supply, and is gathered into corre- 

 sponding veins (Fig. 135) which unite near the liver to form the 

 portal vein. The further course of the blood carried to the liver 

 (partly arterial from the hepatic artery, partly venous from the 

 portal system) has been described already (p. 412). 



