THE FOOD AND DIGESTION 



327 



it up into a number of small divisions, the lobules, each 

 lobule being composed of a series of tubules arranged radially 

 with blood vessels coursing between them. 



The portal vein which takes blood from the stomach, intes- 

 tine, pancreas, and spleen breaks up in the liver (Fig. 105, 

 p. 209), and carries the blood between the lobules. From the 

 interlobular branches, capillaries run inwards and enter a 

 central vein which carries the blood from each lobule, and 

 pours it into the hepatic veins which join the inferior vena 

 cava. The supporting tissue of the liver is supplied by the 

 hepatic artery, -and the ter- 

 minal branches have a very 

 free communication with 

 those of the portal vein. 



The Pancreas is essenti- 

 ally the same in structure as 

 the parotid gland. But in 

 the lobules are certain little 

 masses of epithelium - like 

 cells closely packed to- 

 gether, the Islets of Lan- 

 gerhans (Fig. 145). 



The Nerve Supply of the 

 alimentary canal. The 

 muscles round the mouth 

 are supplied by the fifth, 

 seventh, and twelfth cranial 



nerves. The nerve Supply FiG.145. -Section of Pancreas to show Acini 



-ri of Secreting Cells ; a large duct ; and m 

 Ot the Salivary glands Will the centre an Island of Langerhans. 



be considered later. The 



pharyngeal muscles are supplied by the ninth and tenth 



cranial nerves, and the oesophagus is supplied by the tenth. 



The stomach and intestine get their nerve fibres from two 

 sources (Fig. 126, p. 263) above the descending colon from the 

 vagus and the abdominal sympathetic, and below this from 

 the nervi erigentes and abdominal sympathetic the various 

 fibres passing through the abdominal sympathetic ganglia. 

 In the wall of the stomach and intestine, these nerves end by 

 forming an interlacing set of fibres, with nerve cells upon 

 them, from which fibres pass to the muscles and glands. 



