Studies in the Osteopathic
Basic Principles: Volume
Louisa Burns, M.S., D.O., D.Sc.O.
THE RULE OF THE ARTERY PREVAILS.
Blood Pressure and Lymph.
function of any cell group depends largely upon the pressure of the blood
in the vessels applying it. The cell is bathed in lymph, and this
is derived from the capillaries. The flow of the nutrient lymph,
while probably not altogether independent of a certain secretory activity
on the part of the capillary endothelium, is yet almost absolutely subject
to the laws of osmosis and diffusion. The variations in lymph flow
due to changes in osmotic tension depend upon changes in the quality of
the blood, in the quality of the waste material thrown off by the cells,
and in the rapidity of the flow of the lymph by which the products of cell
metabolism and the unabsorbed foods derived from the blood are carried
away. The lymph varies normally according to the pressure in the
veins and arteries, and the presence of substances in the blood which are
the result of the metabolism of the various organs of the body, or are
taken with the food. Under abnormal conditions, the lymph flow is
affected by very many factors.
Variations in Blood Pressure.
lymph flow depends in part upon the capillary pressure. This follows
the pressure within the arterioles, and this in turn depends upon several
other factors. Arterial pressure is increased by an increased rate
and force of the heartís action, by an increased quantity of the blood
in the vessels, by the contraction of the arterioles in the tissues of
any marked area, or by any interference with the circulation through any
organ or group of vessels. An increased secretion of certain of the
ductless glands, notably the supra-renal capsules, increases the blood
pressure both by initiating an increased force of the heartís action and
by decreasing the caliber of the vessels. The manner in which this
increase in the activity of the non-striated muscles is produced by these
internal secretions is not yet understood. The blood pressure is
decreased by a diminished rate and force of the heartís action, by anything
which decreases the amount of blood in circulation, or by the dilatation
of any considerable area of blood vessels.
blood pressure is practically the same in all vessels of equal rank and
caliber all over the body. The differences due to gravity, to the
pressure of other organs and to other factors are not great under normal
conditions. Under abnormal conditions, however, these factors become
matters of serious import. When the vascular walls lose their tone,
the influence of gravity dilates them most painfully, and the elevation
of the part affected affords great temporary relief.
Blood Pressure and Nutrition.
the arterioles in a given area are dilated, and the systemic pressure is
low, the blood flows slowly through the dilated arteries and the capillaries.
The interchange of gases and of foods is very slow. The diffusion
of the proteids of the blood serum is always a matter of difficulty, only
secured under normal circumstances by the maintenance of a high arterial
pressure. During a period of low pressure, these may be scarcely
diffused at all, and as a result the cells of the body may be insufficiently
nourished, even though the blood itself be fairly normal. The blood
itself does not remain even fairly normal if the pressure remain abnormally
low for any great length of time. The hematopoietic organs are just
as dependent upon the maintenance of a normal pressure within the blood
vessels as are any other organs of the body. Digestion and assimilation
fail in the presence of persistently low blood pressure, and the blood
itself soon becomes very poor, in its serum constituents as well as in
its anatomical elements.
Blood-Pressure and Excretion.
absorption of the waste products of cell metabolism is also hindered during
periods of low pressure. The return flow of the lymph is often retarded
in these cases, and the cells are forced to maintain their functions as
well as they may in the presence of their own excretions, as well as with
a poor food supply. Normally, the carbon dioxid is carried from the
tissues chiefly by the veins. The amount of any gas which can be
absorbed by any liquid depends upon the temperature and pressure.
Now since the temperature of the body remains fairly constant, it is evident
that the absorption of gas by the blood varies directly with the pressure
within the capillaries. In the presence of a low pressure the carbon
dioxid normally formed by the living cells is not properly eliminated.
This failure of the elimination of the carbon dioxid, together with the
oxygen deficiency usually associated with it, is a source of several abnormal
conditions of more or less discomfort and danger.
Blood-Pressure and Flatulence.
digestive activity, a low pressure almost invariably causes the accumulation
of gas within the digestive tract. The habitual occurrence of this
symptom is itself a cause of an abnormal distention and later a dilation
of the stomach or some part of the intestinal tract. Other evils
follow in the train of such dilatation in the due course of events.
The accumulation of gas, in itself, is a matter of grave discomfort and
annoyance, and under some conditions may be a source of danger. The
gases formed by the action of the digestive juices and bacteria upon the
food stuffs in the alimentary canal are, under normal conditions, absorbed
by the blood and eliminated from the lungs. In the presence of an
abnormally low blood pressure, there are retained within the stomach and
intestines, causing pain and considerable annoyance from borborygmi and
Blood-Pressure and Katabolism.
metabolism of the cells in the absence of a proper exchange of oxygen and
carbon dioxid varies greatly from the normal. The waste products
of katabolism are not thoroughly oxidized. In normal metabolism the
waste materials are almost neutral in reaction. The blood remains
alkaline during any amount of metabolism when the normal oxygen supply
and carbon dioxid removal is maintained. But when the proper balance
between these gases is disturbed, the metabolism also is disturbed, and
the katabolic products include complex, poorly oxidized compounds, acid
in reaction, very variable in their chemical relationships and almost invariably
toxic to the cells of the body tissues, and the alkalinity of the blood
liver and the lymphatic glands, and perhaps other adenoid elements of the
body render these substances inert. The kidneys, liver, and other
depurating organs eliminate them from the body as rapidly as possible,
but the powers of these organs are limited, and the symptoms of auto-intoxication
are almost sure to occur sooner or later. The alkalinity of the blood
is lessened by the retention of the normal wastes, by the formation of
the abnormal wastes, and by other factors concerned in the oxygen and carbon
dioxid relation. The bacteriolytic power of the blood is decreased
with the decrease in its alkalinity.
Blood-Pressure and Secretion.
activity of all the glands of the body is subject to variations in answer
to variations in the blood pressure. Any gland, whether it possesses
secretory nerves or not, is more active in the presence of high pressure
than during a decrease in pressure. The effects of the action of
the secretory nerves may mask the variations due to changing blood pressure.
the case of the sweat glands, for example, the secretion may be almost
or quite suspended in the presence of high pressure, or be increased during
periods of low pressure. In all such cases, however, the action of
the secretory nerves is effective only as a stimulation to the katabolic
processes, the nerve influences are not effective in the absence of the
zymogen granules from which the secretion is derived. Secretory nerves
initiate the discharge of the substances already potentially formed within
the substance of the cell protoplasm. The effects of the stimulation
of the secretory nerves fail utterly after a comparatively short period
of activity with a low blood pressure, or when the blood supply is deficient.
When the blood supply is good, and the pressure is high, the serum proteids
are more easily diffusible and the gland is properly nourished. The
oxygen supply and the carbon dioxid removal are also facilitated by the
in the action of the kidneys, especially, are known to depend almost, if
not quite, upon variations in the rapidity of the blood flow. Secretory
nerves have not been demonstrated in them. Given an abnormally low
arterial pressure, the action of the kidneys is insufficient. Given
an abnormally high venous pressure, the action of the kidneys is also deficient.
Given a somewhat increased pressure, the action of the kidneys is also
somewhat increased, but the persistent increase in the blood pressure so
injures the renal cells that malfunction is produced, with the associated
changes in the vascular musculature, as well as changes in the systemic
pressure, affect the activity of all glands. The changes in the metabolism
of the ductless glands in these conditions offer a field for some very
profitable work in investigation. The little study that has been
made of clinical cases in which malfunction of these glands has exercised
very deleterious effects upon the general body metabolism, seems to indicate
that the action of these glands may be very dependent upon vaso-motor influences.
Blood-Pressure and Mentality.
brain itself is not exempt from changes in its activity due to changing
pressure in its vessels. Sleep is accompanied, and, in part at least, produced,
by a lowered pressure due to a general dilatation of the systemic arterioles.
Any considerable lowering of the blood pressure due to any cause is marked
by a sleepiness, or by a stupid, dull feeling. In a series of experiments
performed in the investigation of physical phenomena associated with mental
conditions, it was noticed that the usual effect of mental effort is to
increase the systemic blood pressure.
the lowering of the systemic pressure by the experimental dilatation of
the splanchnic arterioles was followed by decided sleepiness and an inability
to concentrate the attention in the degree to which the subject was accustomed.
The contraction of the splanchnic arterioles by stimulating manipulations
raises the systemic pressure and renders the mental processes more speedy
and the mental pictures more vivid. If the increase in the blood
pressure does not exceed the degree normal to the individual, the experimental
increase of blood pressure was followed by a consciousness of well being,
and by a very rapid, pleasant, and vivid flow of mental processes.
Blood-Pressure and Alienism.
abnormal conditions the effects of changing blood pressure in modifying
mentality are much more pronounced. Melancholia and the apathetic
psychoses are marked by very low pressure. Anything that raises the
blood pressure in these cases in slight degree exercises a beneficial effect
upon the neurosis. The excitable manias are characterized by abnormally
high pressure. The insane manifestations of these are somewhat relieved
if the systemic pressure can be decreased. The pressure changes in
the psychoses are probably in part a cause of the symptoms observed, but
it is also true that emotional reactions produce vaso-motor effects.
fairly normal conditions, a persistently gloomy attitude toward oneís surroundings
lowers blood pressure, and, on the other hand, a low blood pressure renders
the gloomy view the easy one, and the cheerful aspect a matter of considerable
effort. Reasoning from the normal conditions, it appears that the
so-called functional psychoses are in part referable to the metabolic changes
due to deficient or excessive blood pressure, together with the faulty
elimination of waste products usually associated with such conditions.
Effects of High Blood-Pressure.
is evident that the normal activity of any cell group requires the maintenance
of a sufficiently high pressure in the arterioles. The effects of
an abnormally high pressure are not less disastrous than are the effects
of an abnormally low pressure. Too high pressure, if long continued,
leads to an abnormal activity of certain organs of the body, and to their
too speedy fatigue. The kidneys especially are very easily injured
by persistently high blood pressure. The phenomena of arterio-sclerosis
ensue, if the walls of the blood vessels are long subject to too high pressure,
especially if the blood contain toxic irritants which render the cells
more unstable than is their wont. The walls of the blood vessels
are subject to various pathological conditions when they are kept under
too great tension for a sufficient length of time. The heart, also,
is injured by the maintenance of too high a pressure.
The Regulation of Blood-Pressure.
action of the arterioles in maintaining a normal degree of pressure in
the blood vessels is kept regulated by the vaso-motor nerves. These
are axons of the sympathetic neurons, which receive their stimulation from
coordinating centers in the viscero-motor nuclei in the spinal cord, medulla,
pons and mid-brain. Any interference with the pathway by means of
which the nerve impulses are carried to or from the coordinating centers,
must lessen the normal relation between the vascular dilatation and the
functional activity of the different tissues.
condition which abnormally increases the activity of the vaso-motor centers
causes an abnormal vaso-constriction, and any condition which abnormally
decreases the activity of the vaso-motor centers causes an abnormal dilatation
of the vessels. If the vessels are permitted to remain for a long
time dilated, the area of their distribution is injured, and the other
organs of the body are subjected to a decreased blood pressure. If
the vessels of any tissue are forced to remain contracted for any length
of time the tissue undergoes a degenerative process, and usually, if the
condition be not relieved, gangrene ensues. The gangrene of ergotism
is of interest in this connection.
normal conditions, the vessels of any organ become dilated during its activity.
At the same time, and in answer to the same nerve impulses which cause
the local dilatation, the vessels in other parts of the body become contracted,
so that the pressure of the blood in the dilated arterioles remains high,--perhaps
even becomes higher than before the local dilatation occurred. Sometimes,
under abnormal conditions, the vaso-motor impulses are not properly coordinated,
and the dilatation of the vessels in the active structure is not accompanied
by the general vaso-constriction. In such a case, the general blood
pressure is lowered, the functional activity of the whole body is lessened,
and the elimination of the waste products of such metabolism as does occur
is decreased. The active structure whose vessels are dilated lacks
the normal pressure, and its function is thereby lessened. This malfunction
and the abnormal conditions of pressure and nutrition initiate sensory
impulses, which, reaching the vaso-motor centers, effect still further
dilatation of the vessels in the organ or cell group whose activity
has caused the whole series of reactions.
coordination of all, or nearly all, of the vaso-motor nerves of the body
is essential to the normal activity of any important organ or cell group.
This coordination fails under the following conditions:--
abnormalities of structure may interfere with the normal passage of sensory
impulses from any part of the body or of vaso-motor impulses to it.
trunks may be subjected to the steady pressure which decreases their power
to transmit impulses, or to pressure which varies, as the pressure of a
pulsating artery, etc., and so exercises a continual stimulating effect
upon its fibers.
of the vertebrae may either increase or decrease the activity of the subsidiary
centers, by initiating abnormal sensory impulses.
neuron threshold of any center may be either abnormally raised or abnormally
lowered by abnormal conditions of nutrition or function.
structural conditions of the heart or of the vessel walls may render them
inefficient, in the presence of the normal nerve impulses.
impulses from the brain, especially from the basal ganglia, may interfere
with the action of the lower centers.
Ergotism, Oslerís Practice of Medicine.
Raynaudís Disease, McConnell and Teall.
Raynaudís Disease, J. L. Adams in A. O. A. Case Reports.