310 THE ADRENAL, GENERAL MOTOR, AND VAGAL SYSTEMS. 



branches of the "general motor system"; (2) branches of the vagus 

 system. 



(a) Each branch of the "general motor system" subdivides 

 into two branches: one of these supplies the arterioles; the other 

 subdivides into two branches, one of which is distributed to the 

 muscles and the other to the glands. 



(b) The branches of the vagus subdivide in the same manner 

 and inosculate with the general motor filaments and plexuses ex- 

 cept with those distributed to arterioles that supply capillaries to 

 the glands, and probably end in the muscularis mucosce. 



4- When the stomach is in the resting state, the general motor 

 nerves alone transmit impulses to all the structures of the organ, 

 including the glands, which during this period elaborate their 

 secretory products. 



5. When as a result of physical reflex or psychical stimuli the 

 stomach becomes functionally active, the vagus impulses impose 

 their rhythm upon the general motor nerves, and the vagus system 

 assumes control of the digestive process. 



(a) The extrinsic arteries are constricted beyond their normal 

 tonic caliber; the speed of the blood-flow to the stomach-walls is 

 increased and peristaltic action excited. 



(b) The intrinsic arteries that do not supply capillaries to 

 the glands are constricted also, thus forcing the blood into these 

 capillaries and inducing glandular activity and the production of 

 gastric juice. 



(c) Pepsinogen (?) and rennin are secreted as a direct result 

 of increased metabolism in the central cells. 



(d) Hydrochloric acid is secreted as a result of the rise of 

 temperature incident upon increased metabolism, the reaction be- 

 tween Cl and H when HCl is formed in the parietal cells only 

 occurring when 89.5 C. (103.1 F.) is reached: i.e., approxi- 

 mately the temperature of the gastric structures during functional 

 activity. 



THE INTESTINES AND THEIR PROPHYLACTIC FUNCTIONS. 

 The stomach is, in reality, but a dilated portion of the gen- 

 eral digestive tract. Its four coats the mucous or glandular, 

 the submucous, the muscular, and the serous are continued in 

 the intestinal walls, and what variations are present are limited 

 to the mucous and submucous layers and the glandular struct- 



