A wave, not a whole-organ squeeze
The contraction travels along the stomach wall towards the antrum and pylorus. The timing and narrow outlet create mixing and retropulsion. Watch the narrowing travel along the wall while food circulates inside.
BIOLOGY / THE LIVING BODY
Stomach · mix, digest, release
Swallowed food enters a muscular storage and mixing chamber. Waves of contraction churn it with gastric juice; acid and enzymes begin protein digestion. Watch a small meal become chyme and leave gradually through the pylorus.
Why does food stay in the stomach instead of falling straight through?
The oesophagus enters above; the pylorus leads into the duodenum below. Open the stomach to see its folds (rugae). Food pieces and fluid are enlarged teaching markers. The animation compresses a process that normally takes much longer than a few seconds.
Anatomical view
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Food piecesMixed chymeContracting muscle
Where does absorption mainly happen?
The stomach begins protein digestion and controls delivery to the intestine. The small intestine, with its very large absorptive surface, is where most nutrients enter the body.
Check your understanding · Would acid without pepsin perform the same protein digestion?
No. Acid helps denature proteins and provides a suitable pH; pepsin catalyses the cleavage of peptide bonds.