Why yes,... it is the stomach's rugae, large folds along the stomach's wall
that create more surface area for absorption and secretion of chemicals.
"How neat!" you think. The wave motion is much like being on a little boat
in the middle of the ocean. These gentle waves, peristalsis, combined with juices secreted
from the gastric glands, serve to mechanically digest the
bolus further into a thin liquid called chyme. The chemical digestion of protein also begins in the stomach with an
enzyne called pepsin. Pepsin breaks the peptide bonds between the amino acids. Other enzymes that aid in the chemical digestion of
other materials include gastric lipase and pancreatic lipase. Both help break down carbohydrates.
What's that over there? Could it be a microbe?
Well,... it was a microbe. The intense acidic fluid in the stomach has killed most of the microbes
in Fred's last meal. In addition to the mass murder of harmful microbes, the acid in the stomach also
stimulates the secretion of bile and pancreatic juice.
As you head toward yet another sphincter (this time the pyloric sphincter), the waves become bigger and bigger. What's that stuff you see
beyond the sphincter? They look like little fingers...
