Processing of food in the stomach

The emptying of food from the stomach is regulated by neural and hormonal mechanisms. The arrival of food in the proximal stomach (fundus and corpus) causes an adaptive relaxation mediated by neuronal release of vasoactive intestinal polypeptide and nitric oxide. The relaxation accommodates the increasing gastric volume without an increase in the pressure gradient between the proximal and distal stomach. The presence of food in the stomach also induces increased antral peristaltic activity (grinding) with propulsion and retropulsion of food particles. The combined mechanical and enzymatic activity gradually decrease the size of food particles until they are sufficiently small (1–2 mm) to allow passage into the duodenum.

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