The various humoral (chemical) factors controlling the different secretions in the gastro-intestinal tract may be summarised as follows:
1. For Gastric Secretion:
i. Gastrin- Responsible for gastric phase.
ii. A chemical substance may be a hormone or secretagogue – Responsible for intestinal phase.
iii. Enterogastrone- Inhibits gastric secretion.
2. For Pancreatic Secretion:
i. Secretin- Main chemical stimulus.
ii. Pancreozymin.
iii. Foodstuffs.
3. For Succus Entericus:
i. Products of protein digestion.
ii. Enterocrinin.- Probably chief stimulus.
iii. Duocrinin.
4. For Bile Secretion:
i. Bile salts- Chief stimulus.
ii. Fat and Protein food.
iii. Hepatocrinin acting on liver cells.
iv. Cholecystokinin- Stimulates contraction of gall-bladder.