OF THE MOTION, ACTION, AND OFFICE OF THE HEART
From these and other observations of the like kind, I am persuaded it
will be found that the motion of the heart is as follows:
First of all, the auricle contracts, and in the course of its
contraction throws the blood, (which it contains in ample quantity
as the head of the veins, the storehouse, and cistern of the blood,)
into the ventricle, which, being filled, the heart raises itself
straightway, makes all its fibres tense, contracts the ventricles, and
performs a beat, by which beat it immediately sends the blood supplied
to it by the auricle into the arteries; the right ventricle sending its
charge into the lungs by the vessel which is called vena arteriosa, but
which, in structure and function, and all things else, is an artery;
the left ventricle sending its charge into the aorta, and through this
by the arteries to the body at large.
These two motions, one of the ventricles, another of the auricles,
take place consecutively, but in such a manner that there is a kind
of harmony or rhythm preserved between them, the two concurring in
such wise that but one motion is apparent, especially in the warmer
blooded animals, in which the movements in question are rapid. Nor
is this for any other reason than it is in a piece of machinery, in
which, though one wheel gives motion to another, yet all the wheels
seem to move simultaneously; or in that mechanical contrivance which
is adapted to firearms, where the trigger being touched, down comes
the flint, strikes against the steel, elicits a spark, which falling
among the powder, it is ignited, upon which the flame extends, enters
the barrel, causes the explosion, propels the ball, and the mark is
attained--all of which incidents, by reason of the celerity with which
they happen, seem to take place in the twinkling of an eye. So also
in deglutition: by the elevation of the root of the tongue, and the
compression of the mouth, the food or drink is pushed into the fauces,
the larynx is closed by its own muscles, and the epiglottis, whilst the
pharynx, raised and opened by its muscles no otherwise than is a sac
that is to be filled, is lifted up, and its mouth dilated; upon which,
the mouthful being received, it is forced downwards by the transverse
muscles, and then carried farther by the longitudinal ones. Yet are
all these motions, though executed by different and distinct organs,
performed harmoniously, and in such order, that they seem to constitute
but a single motion and act, which we call deglutition.
Even so does it come to pass with the motions and action of the heart,
which constitute a kind of deglutition, a transfusion of the blood
from the veins to the arteries. And if any one, bearing these things
in mind, will carefully watch the motions of the heart in the body of
a living animal, he will perceive not only all the particulars I have
mentioned, viz. the heart becoming erect, and making one continuous
motion with its auricles; but farther, a certain obscure undulation
and lateral inclination in the direction of the axis of the right
ventricle, [the organ] twisting itself slightly in performing its work.
And indeed every one may see, when a horse drinks, that the water is
drawn in and transmitted to the stomach at each movement of the throat,
the motion being accompanied with a sound, and yielding a pulse both
to the ear and the touch; in the same way it is with each motion of
the heart, when there is the delivery of a quantity of blood from
the veins to the arteries, that a pulse takes place, and can be heard
within the chest.
The motion of the heart, then, is entirely of this description, and
the one action of the heart is the transmission of the blood and its
distribution, by means of the arteries, to the very extremities of the
body; so that the pulse which we feel in the arteries is nothing more
than the impulse of the blood derived from the heart.
Whether or not the heart, besides propelling the blood, giving it
motion locally, and distributing it to the body, adds anything else
to it,--heat, spirit, perfection,--must be inquired into by and by,
and decided upon other grounds. So much may suffice at this time, when
it is shown that by the action of the heart the blood is transfused
through the ventricles from the veins to the arteries, and distributed
by them to all parts of the body.
So much, indeed, is admitted by all [physiologists], both from the
structure of the heart and the arrangement and action of its valves.
But still they are like persons purblind or groping about in the dark;
and then they give utterence to diverse, contradictory, and incoherent
sentiments, delivering many things upon conjecture, as we have already
had occasion to remark.
The grand cause of hesitation and error in this subject appears to
me to have been the intimate connection between the heart and the
lungs. When men saw both the vena arteriosa [or pulmonary artery]
and the arteriæ venosæ [or pulmonary veins] losing themselves in the
lungs, of course it became a puzzle to them to know how or by what
means the right ventricle should distribute the blood to the body, or
the left draw it from the venæ cavæ. This fact is born witness to by
Galen, whose words, when writing against Erasistratus in regard to
the origin and use of the veins and the coction of the blood, are the
following:[26] “You will reply,” he says, “that the effect is so;
that the blood is prepared in the liver, and is thence transferred to
the heart to receive its proper form and last perfection; a statement
which does not appear devoid of reason; for no great and perfect work
is ever accomplished at a single effort, or receives its final polish
from one instrument. But if this be actually so, then show us another
vessel which draws the absolutely perfect blood from the heart, and
distributes it as the arteries do the spirits over the whole body.”
Here then is a reasonable opinion not allowed, because, forsooth,
besides not seeing the true means of transit, he could not discover the
vessel which should transmit the blood from the heart to the body at
large!
[26] De Placitis Hippocratis et Platonis, vi.
But had any one been there in behalf of Erasistratus, and of that
opinion which we now espouse, and which Galen himself acknowledges in
other respects consonant with reason, to have pointed to the aorta
as the vessel which distributes the blood from the heart to the rest
of the body, I wonder what would have been the answer of that most
ingenious and learned man? Had he said that the artery transmits
spirits and not blood, he would indeed sufficiently have answered
Erasistratus, who imagined that the arteries contained nothing but
spirits; but then he would have contradicted himself, and given a
foul denial to that for which he had keenly contended in his writings
against this very Erasistratus, to wit, that blood in substance
is contained in the arteries, and not spirits; a fact which he
demonstrated not only by many powerful arguments, but by experiments.
But if the divine Galen will here allow, as in other places he does,
“that all the arteries of the body arise from the great artery, and
that this takes its origin from the heart; that all these vessels
naturally contain and carry blood; that the three semilunar valves
situated at the orifice of the aorta prevent the return of the blood
into the heart, and that nature never connected them with this, the
most noble viscus of the body, unless for some most important end;”
if, I say, this father of physic admits all these things,--and I quote
his own words,--I do not see how he can deny that the great artery is
the very vessel to carry the blood, when it has attained its highest
term of perfection, from the heart for distribution to all parts of
the body. Or would he perchance still hesitate, like all who have
come after him, even to the present hour, because he did not perceive
the route by which the blood was transferred from the veins to the
arteries, in consequence, as I have already said, of the intimate
connexion between the heart and the lungs? And that this difficulty
puzzled anatomists not a little, when in their dissections they found
the pulmonary artery and left ventricle full of thick, black, and
clotted blood, plainly appears, when they felt themselves compelled
to affirm that the blood made its way from the right to the left
ventricle by sweating through the septum of the heart. But this I fancy
I have already refuted. A new pathway for the blood must therefore be
prepared and thrown open, and being once exposed, no further difficulty
will, I believe, be experienced by any one in admitting what I have
already proposed in regard to the pulse of the heart and arteries,
viz. the passage of the blood from the veins to the arteries, and its
distribution to the whole of the body by means of these vessels.