Four Main Function of the Digestive System
Motility: Mechanical breakdown and mixing of
ingested nutrients by smooth muscle movements, passage of
nutrients through the digestive tract, and elimination of
undigested or unabsorbed residues from the body.
Secretion: Release of enzymes, hormones, and
other substances that take part in digestion.
Digestion: Chemical reduction of ingested
nutrients into particles, then into molecules small enough to
cross the lining of the gut and reach the internal environment of
the body.
Absorption: Passage of digested nutrients from
the gut lumen into the blood or lymph, which distributes them
throughout the body.