11.
Wavelike contractions of the three pharyngeal c
r muscles force the
bolus into the beginning of the
s.
As the larynx is raised along with the tongue and the hyoid bone, its epi
s
turns down over the opening of the
. Thus, food is prevented from entering the
lower
passageway.
12.
The esophagus is a tube with m
r walls. It extends from the
above,
through the neck and thorax, to the
in the abdomen. Wavelike contractions,
called p
s, move the bolus through the esophagus to the stomach.
13.
Because of the stomach's capacity, the individual can engage in activities other
than
g. In addition, certain
ve processes are initiated in the stomach.
14.
One way the stomach is adapted as a storage area is that its wall is quite
ble. Its lining has folds called
ae.
Another adaptation is that, at each end, there is a
e or similar structure to
keep contents from leaving. The "gastroesophageal
e" has not been
demonstrated anatomically. At the other end of the stomach is the well-developed
______c valve.
15.
The mucosal lining of the stomach contains a number of
c glands. The
mixture produced by the stomach, called
e, is quite (acid) (basic).
The three layers of muscles help to ensure that the contents of the stomach are
thoroughly
d.
16.
Digestion occurs through the actions of chemicals called
s. The end
products (molecules or particles) are small enough to be absorbed through the walls of
the small
s.
Digestive enzymes are present to maintain the appropriate r
s of reaction. A
catalyst is a substance that improves the
of reaction without being
d itself.
Digestive enzymes are
s. Without digestive enzymes, digestion would be too
____w to provide materials needed by the body.
MD0007
6-18