A Handbook of Health | Page 8

glands, and the furrows, or folds,
of the lining.]
The Peptic Juice. The cells of the stomach glands manufacture and pour
out a slightly sour, or acid, juice containing a ferment called pepsin.
The acid, which is known as hydrochloric acid, and the pepsin together
are able to melt down pieces of meat, egg, or curds of milk, and
dissolve them into a clear, jelly-like fluid, or thin soup, which can
readily be absorbed by the cells lining the intestine.[4]
You can see now why you shouldn't take large doses of soda or other
alkalies, just because you feel a little uncomfortable after eating. They
will make your stomach less acid and perhaps relieve the discomfort,
but they stop or slow down digestion. Neither is it well to swallow
large quantities of ice-water, or other very cold drinks, at meal times, or
during the process of digestion. As digestion is largely getting the food
dissolved in water, the drinking of moderate quantities of water, or
other fluids, at meals is not only no hindrance, but rather a help in the
process. The danger comes only when the drink is taken so cold as to
check digestion, or when it is used to wash down the food in chunks,

before it has been properly ground by the teeth.
[Illustration: A LONGITUDINAL SECTION OF STOMACH, OR
PEPTIC, GLANDS
(Greatly magnified)
The long duct of each gland is but a deep fold of the stomach lining
(see note, p. 11). Into this duct the ranks of cells around it pour out the
peptic juice.]
Digestion in the Stomach. Although usually a single, pear-shaped
pouch, the stomach, during digestion, is practically divided into two
parts by the shortening, or closing down, of a ring of circular muscle
fibres about four inches from the lower end, throwing it into a large,
rounded pouch on the left, and a small, cone-shaped one on the right.
The gullet, of course, opens into the large left-hand pouch; and here the
food is stored as it is swallowed until it has become sufficiently melted
and acidified (mixed with acid juice) to be ready to pass on into the
smaller pouch. Here more acid juice is poured out into it, and it is
churned by the muscles in the walls of the stomach until it is changed
to a jelly-like substance.
Digestion in the Small Intestine. The food-pulp now passes on into the
small intestine, where it is acted upon by two other digestive juices--the
bile, which comes from the liver, and the pancreatic juice, which is
secreted by the pancreas.
The liver and the pancreas are a pair of large glands which have budded
out, one on each side of the food tube, about six inches below where
the food enters the small intestine from the stomach. The liver[5]
weighs nearly three pounds, and the pancreas about a quarter of a
pound.
Of these two glands, the pancreas, though the smaller, is far more
important in digestion. In fact, it is the most powerful digestive gland in
the body. Its juice, the pancreatic juice, can do everything that any
other digestive juice can, and do it better. It contains a ferment for

turning starch into sugar, which is far more powerful than that of the
saliva; also another (trypsin), which will dissolve meat-stuffs nearly
twice as fast as the pepsin of the stomach can; and still another, not
possessed by either mouth or stomach glands, which will melt fat, so
that it can be sucked up by the lining cells of the intestine.
What does this great combination of powers in the pancreas mean? It
means that we have now reached the real centre and chief seat of
digestion, namely, the small intestine, or upper bowel. This is where
the food is really absorbed, taken up into the blood, and distributed to
the body. All changes before this have been merely preparatory; all
after it are simply a picking up of the pieces that remain.
In general appearance, this division of the food tube is very
simple--merely a tube about twenty feet long and an inch in diameter,
thrown into coils, so as to pack into small space, and slung up to the
backbone by broad loops of a delicate tissue (mesentery). It looks not
unlike twenty feet of pink garden hose.
The intestine also is provided with glands that pour out a juice known
as the intestinal juice, which, although not very active in digestion,
helps to melt down still further some of the sugars, and helps to prevent
putrefaction, or decay, of the food from the bacteria[6] which swarm in
this part of the tube.
By the time the food has gone a third of the way down the small
intestine, a good share of the starches in it