Begins in the mouth. Teeth grind the food while
three pairs of salivary glands pour salivary juice (saliva) into the mouth.
Saliva contains the enzyme salivary amylase (ptyalin), which begins the
digestion of starch. The moistened, chewed food is swallowed and moves through
the throat into the food tube, or esophagus. The esophagus has no digestive
function but moves the food into the stomach by waves of muscle contractions
called peristalsis. Chemical digestion is known as hydrolysis. Extracellular
digestion takes place outside of cells. Intracellular digestion takes place
inside of cells within cell vacuoles.
