It is clear from the diagram above, that during digestion, large quantities of digestive secretions are produced. If secretions are produced at inappropriate times, not only is production wasteful, but it could also be damaging. The control of secretions is therefore very important.

The sensation of food in the mouth, or even the anticipation of eating is enough to trigger your [?] nervous sytem into action and this sends impulses down your [?] nerve to the stomach. Nerves supplying the top end of the stomach trigger the release of from the [?] and [?] from the [?], whilst the vagus that innervates the lower end of the stomach tends to stimulate the [?] cells to release . This hormone then passes via the blood to the oxyntic mucosa, further enhancing the release of acid and protease.

Once food has entered the stomach, protein breakdown products like and [?] of the stomach wall triggers activity in a nerve net, stimulating the production fo more gastric juices and also sending impulses back up the nerve to further stimulate vagus motor activity.
Even after food starts to leave the stomach, the [?] itself releases some hormone that although designed to stimulate the pancreas, also reaches the stomach via the blood.

It should be noted that and themselves even without solid food stimulate the production of gastric juices, so people with gastric ulcers should try and avoid these, particularly when not accompanied with food as it could lead to extremely dangerous perforated ulcers.