SECRETION.
414. In the human body are found many fluids and solids of dissimilar
appearance and character. These are produced by the action of organs,
some of which are of simple structure, while others are very complicated
in their arrangement. These organs are called _Se-cre'to-ry_.
ANATOMY OF THE SECRETORY ORGANS.
415. The SECRETORY ORGANS are the _Ex-ha'lants_, _Fol'li-cles_, and
the _Glands_.
416. The EXHALANTS were supposed to be terminations of arteries or
capillaries. The external exhalants terminate on the skin and mucous
membranes; the internal in the cellular and medullary tissues.
(Appendix I.)
[Illustration: Fig. 86. A secretory follicle. An artery is seen, which
supplies the material for its secretion. Follicles are also supplied with
veins and organic nerves.]
417. The FOLLICLES are small bags, or sacs, situated in the true skin,
and mucous membrane. The pores seen on the skin are the outlets of
these bodies.
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414. How are the fluids and solids of the body produced? 415-419.
_Give the anatomy of the secretory organs._ 415. Name the secretory
organs. 416. Describe the exhalants. What is represented by fig. 86?
417. Define follicles.
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418. The GLANDS are soft, fleshy organs, and as various in their
structure, as the secretions which it is their function to produce.
Each gland is composed of many small lobules united in a compact mass,
and each lobule communicates by a small duct with the principal
outlet, or duct of the organ. Every gland is supplied with arteries,
veins, lymphatics, and nerves. These, with the ducts, are arranged in
a peculiar manner, and connected by cellular membrane.
419. There are two classes of glands, one for the modification of the
fluids which pass through them, as the mesenteric and lymphatic
glands; and the other for the secretion of fluids which are either
useful in the animal economy, or require to be rejected from the
body.
[Illustration: Fig. 87. 1, 1, A secretory gland. 2, 2, Minute ducts that
are spread through the glands. These coalesce to form the main duct, 3.]
PHYSIOLOGY OF THE SECRETORY ORGANS.
420. SECRETION is one of the most obscure and mysterious functions of
the animal economy. "It is that process by which various substances
are separated from the blood, either with or without experiencing any
change during their separation." Not only is the process by which
substances are separated from the blood, called secretion, but the
same term is also applied to substances thus separated. Thus
physiologists say, that by the process of secretion, bile is formed by
the liver; and also, that bile is the secretion of this organ.
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418. Give the structure of the glands. 419. How are the glands
arranged? 420-431. _Give the physiology of the secretory organs._ 420.
What is secretion?
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421. The secreted fluids do not exist in that form in the blood,
but most of the elements of which they are made do exist in this
fluid, and the "vessels by which it is accomplished may well be called
the architects and chemists of the system; for out of the same
material--the blood--they construct a variety of wonderful fabrics
and chemical compounds. We see the same wonderful power possessed,
also, by vegetables; for out of the same materials the olive prepares
its oil, the cocoa-nut its milk, the cane its sugar, the poppy its
narcotic, the oak its green pulpy leaves, and its dense woody fibre.
All are composed of the same few, simple elements, arranged in
different order and proportions."
422. "In like manner we find the vessels, in animated bodies, capable
of forming all the various textures and substances which compose the
frame; the cellular tissue, the membranes, the ligaments, the
cartilages, the bones, the marrow, the muscles with their tendons, the
lubricating fluid of the joints, the pulp of the brain, the
transparent jelly of the eye; in short, all the textures of the
various organs of which the body is composed, consist of similar
ultimate elements, and are manufactured from the blood."
423. Of the agents that produce or direct the different secretions, we
have no very accurate knowledge. Some have supposed this function to
be mechanical, others a chemical process, but experiments prove that
it is dependent on nervous influence. If the nerves are divided which
are distributed to any organ, the process of secretion is suspended.
It is no uncommon occurrence, that the nature of milk will be so
changed from the influence of anger in the mother, as to cause
vomiting, colic, and even convulsions, in the infant that swallows it.
Unexpected intelligence either of a pleasant or unpleasant character,
by its influence on the nervous system, will frequently destroy the
appetite. Sometimes mental agitation, as fear, will cause a cold sweat
to pervade the surface of the body.
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421. What is said respecting secreted substances? Do vegetables
possess the property of secretion? 422. From what are the various
textures formed? 423. Have we accurate knowledge of the agents that
produce secretion?
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424. Secretions are constantly maintained, during life, from the
serous membrane, by the action of the internal exhalants. The fluid
which is exhaled bears some resemblance to the serum of the blood. Its
use is to furnish the organs, which are surrounded by this membrane,
with a proper degree of moisture, and thus enables them to move easily
on each other, as those within the chest and abdomen.
425. The cellular tissue exhales a serous fluid, and when it becomes
excessive in quantity, general dropsy is produced. Fat is another
secretion, which is thrown out, in a fluid state, from the cellular
membrane. It is deposited in little cells, and exists in the greatest
abundance between the skin and the muscles. Its use seems to be, to
form a cushion around the body for its protection; to furnish
nutriment for the system when food cannot be taken; to supply the
carbon and hydrogen necessary to sustain the generation of heat, when
these articles of combustion are not otherwise furnished. The
_med'ul-la-ry_ substance, (marrow,) in the cavities of the long bones,
is very much like fat.
_Observation._ During sickness, if there is not emaciation or
absorption of this secretion, it is considered an unfavorable symptom,
because it indicates a want of power in the absorbing system, which is
among the last to be affected.
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How is it proved that secretion depends on nervous influence? 424.
What is said of the secretions from the serous membrane? 425. From
what tissue is a serous fluid exhaled? What is the effect when this
fluid becomes excessive in quantity? What is fat? Its use? What is
marrow?
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426. The mucous secretion is a transparent, viscid fluid which is
secreted by those membranes that line the cavities of the body, which
have an external communication, as the trachea and alimentary canal.
This secretion serves to protect these parts from the influence of the
air, and concurs, by means of its peculiar properties, in the
performance of their functions. 427. There are two external
secretions, namely, one from the skin, called perspiration, and the
other from the lungs. The cutaneous exhalation, or transpiration[14]
exists in two forms, called sensible perspiration (sweat) and
insensible perspiration. The pulmonary exhalation is the most
important and universal, and closely resembles that of the skin.
[14] _Transpiration_ is a term often used generically, to signify the
passage of fluids or gases through membranes, internally or
externally; but _perspiration_ is a specific term, signifying
transpiration on to the external surface.
428. The follicles are found only in the skin and mucous membrane.
They secrete an oily, unctuous substance, which mixes with the
transpiration, and lubricates the skin. At the root of each hair there
is a minute follicle, which secretes the fluid that oils the hair. The
wax in the passage of the ear is secreted from these bodies.
429. All the blood distributed to the different glands is similar in
composition and character; but the fluids secreted by them, vary in
appearance in a remarkable degree. The office of the glands appears to
be principally to form different secretions. Thus the salivary glands
secrete the insipid saliva; the lachrymal glands, the saline tears;
the liver, the yellow, ropy bile; and the kidneys, the acrid urine.
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426. What is said relative to the mucous secretion? 427. Name the
external secretions. 428. Give the office of the follicles. 429. What
appears to be the principal office of the glands? 430. Mention a
secretion produced in a particular emergency.
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430. Some secretions are evidently produced only in particular
emergencies, as is seen in the increased secretion of bony matter when
a limb is broken.
431. When any substance which is not demanded for nutrition, or does
not give nourishment to the system, is imbibed by the lymphatic
vessels, and conveyed into the blood, it is eliminated in the
secretions.
_Illustration._ A few years since, a poor inebriate was carried to a
London hospital in a state of intoxication. He lived but a few hours.
On examining his brain, nearly half a gill of fluid, strongly
impregnated with gin, was found in the cavities of this organ. This
was secreted from the vessels of the brain.
HYGIENE OF THE SECRETORY ORGANS.
432. _Unless the secretions are regularly maintained, disease will be
the ultimate result._ Let the secretions from the skin be suppressed,
and fever or some internal inflammation will follow. If the bile is
impeded, digestion will be impaired. If any other secretion is
suppressed, it will cause a derangement of the various internal
organs.
_Observation._ Ardent spirits derange the secretions, and change the
structure of the brain. This is one reason why inebriates do not
generally live to advanced age.
433. _The quantity of blood influences the character of the
secretions._ If it is lessened to any great extent, the secretions
will be lessened as well as changed in character.
_Illustration._ When a person has lost a considerable quantity of
blood, there is a sensation of thirst in the fauces, attended with a
cold, pale, dry skin. When reaction comes on, the perspiration is
cold, attended with nausea, and sometimes vomiting.
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431. What becomes of those substances imbibed by the lymphatics that
do not give nourishment to the body. 432-437. _Give the hygiene of the
secretory organs._ 432. What effect on the system when the secretions
are not regularly maintained? 433. Does the quantity of blood
influence the secretions? Give an illustration.
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434. _The secretory organs require the stimulus of pure blood._ If
this fluid is vitiated, the action of the secretory organs will be
more or less modified. Either the quantity will be affected or the
quality will be altered.
_Observation._ The impurity of the blood arising from the inhalation
of the vitiated air of sleeping rooms, diminishes and changes the
character of the secretions of the mouth and stomach. This accounts
for the thirst, coated tongue, and disagreeable taste of the mouth
when impure air is breathed during sleep. The disease it induces, is
indigestion or dyspepsia.
435. _The amount of action modifies the condition of the secretory
organs._ When a secretory organ is excessively stimulated, its vigor
and energy are reduced. The subsequent debility may be so great as to
suppress or destroy its functional power.
_Illustrations._ 1st. In those sections of the country where flax is
spun on a "foot-wheel," it is not unfrequent that the spinners moisten
the thread with the secretions of the mouth. This seems to operate
economically for a time, but debility of the salivary organs soon
follows, which incapacitates them from supplying saliva sufficient to
moisten the food, producing in a short time disease of the digestive
organs.
2d. The habit of continual spitting, which attends the chewing of
tobacco and gums, and other substances, between meals, induces
debility, not only of the salivary glands, but of the system
generally.
436. _One secretory organ may do the office of another._ This
increased action of a secretory organ may be sustained for a limited
time without permanent injury, but, if long continued, a diseased
action of the organ will follow. Of morbid secretions we have examples
in the ossification of the valves of the heart, cancerous and other
tumors.
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434. What is the effect of impure blood on the secretory organs? 435.
What results from stimulating excessively a secretory organ? How is
this illustrated? 436. What is the effect when one secretory organ
performs the office of another?
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_Observation._ In the evenings of the warm season, a chill upon the
impressible skin, that suppresses the perspiration, is frequently
followed by a diarrhoea, dysentery, or cholera morbus. These can be
prevented by avoiding the chill. An efficient means of relief, is
immediately to restore the skin to its proper action.
437. _The secretions are much influenced by the mind._ How this is
effected, it is difficult to explain; but many facts corroborate it.
Every one has felt an increased action of the tear-glands from
distressing feelings. Cheerfulness of disposition and serenity of the
passions are peculiarly favorable to the proper performance of the
secretory function. From this we may learn how important it is to
avoid such things as distract, agitate, or harass us.
_Observation._ In fevers and other diseases, when the skin, mouth, and
throat are dry from a suppression of the secretions, let the mind of
the patient be changed from despondency to hope, and the skin and the
membrane that lines the mouth and throat will exhibit a more moist
condition, together with a general improvement of the vital organs of
the system. Consequently, all just encouragement of the restoration to
health should be given to a sick person.
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Give examples of morbid secretions. What is one cause of dysentery and
cholera morbus? How can these affections he relieved? 437. Show the
influence of the mind on the secretions. Mention instances of its
influence.
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