EXTRA: Curiosities
- The stomach produces
acids for help the process of digestion. But, this acid is very corrosive also
for the stomach. For that reason, the stomach must protect of himself. For
protect himself make a layer of "mucus", that is renew every two weeks.
- One
time, the food left the mouth, the food doesn't "fall down" for the action of
gravity. The muscles of the esophagus contract and relax and push cud to
stomach. If for coincidence, you are eating face down, the food can arrive
until the stomach thanks to this process.