The People's Common Sense Medical Adviser in Plain English: or, Medicine Simplified, 54th ed., One Million, Six Hundred; and Fifty Thousand — John Stuart Mill — John Shaqi
The People's Common Sense Medical Adviser in Plain English: or, Medicine Simplified, 54th ed., One Million, Six Hundred; and Fifty Thousand
John Stuart Mill · en
[Illustration: Fig. 34.
Digestive organs. _3_. The tongue. _7_. Parotid
gland. _8_. Sublingual gland. _5_. Esophagus. _9_.
Stomach. _10_. Liver. _11_. Gall-bladder, _14_. Pancreas.
_13, 13_. The duodenum. The small and large intestines
are represented below the stomach.]
Digestion is effected in those cavities which we have described as parts
of the alimentary canal. The food is first received into the mouth,
where it is masticated by the teeth, and, after being mixed with mucus
and saliva, is reduced to a mere pulp; it is then collected by the
tongue, which, aided by the voluntary muscles of the throat, carries the
food backward into the pharynx, and, by the action of the involuntary
muscles of the pharynx and esophagus, is conveyed to the stomach. Here
the food is subjected to a peculiar, churning movement, by the alternate
relaxation and contraction of the fibers which compose the muscular wall
of the stomach. As soon as the food comes in contact with the stomach,
its pinkish color changes to a bright red; and from the numerous tubes
upon its inner surface is discharged a colorless fluid, called the
_gastric juice_, which mingles with the food and dissolves it. When the
food is reduced to a liquid condition, it accumulates in the pyloric
portion of the stomach. Some distinguished physiologists believe that
the food is kept in a gentle, unceasing, but peculiar motion, called
_peristaltic_, since the stomach contracts in successive circles. In the
stomach the food is arranged in a methodical manner. The undigested
portion is detained in the upper, or cardiac extremity, near the
entrance of the esophagus, by contraction of the circular fibers of the
muscular coat. Here it is gradually dissolved, and then carried into the
pyloric portion of the stomach. From this, then, it appears, that the
dissolved and undissolved portions of food occupy different parts of the
stomach. After the food has been dissolved by the gastric fluid, it is
converted into a homogeneous, semi-fluid mass, called _chyme_. This
substance passes from the stomach through the pyloric orifice into the
duodenum, in which, by mixing with the bile and pancreatic fluid, its
chemical properties are again modified, and it is then termed _chyle_,
which has been found to be composed of three distinct parts, a
reddish-brown sediment at the bottom, a whey-colored fluid in the
middle, and a creamy film at the top. Chyle is different from chyme in
two respects: First, the alkali of the digestive fluids, poured into the
duodenum, or upper part of the small intestine, neutralizes the acid of
the chyme; secondly, both the bile and the pancreatic fluid seem to
exert an influence over the fatty substances contained in the chyme,
which assists the subdivision of these fats into minute particles. While
the chyle is propelled along the small intestine by the peristaltic
action, the matter which it contains in solution is absorbed in the