USE OF THE INSPIRED OXYGEN WITHIN THE SYSTEM.
There is none of the inspired oxygen returned to the lungs by the circulation. What becomes of it, or what its use within the system, has not been written for our learning. It is not retained in the blood, nor is it animalised; nothing yields less oxygen than animal matter. To convey "carbon" out of the system, and somehow purify the blood, is the supposed service; but if so, should it not be included in every expiration and of the inspiration quantity? but which is not the case.
Harvey proved that the blood circulates, but left undiscovered what keeps in motion the inert fluid, except the systole, which the inert heart cannot effect on itself. No organ can do anything of itself, the whole being composed of inert substance, and nothing else; even the life of the body, whatever it may be, leaves the function of every organ, not excepting that of the brain, dependent on the general pressure.
By the general pressure the air is forced into, but not through or beyond the lungs which it inflates, and inflates nothing else. Within the blood-vessels it would prove fatal; and although from it the blood derives that by which it becomes arterialised, yet the blood and air do not come in contact, extravasation and pulmonary rupture must happen, did the lungs permit the blood and air coming together, or in immediate contact. Of the air of an inspiration, the oxygenating imponderable element only can permeate the pulmonary tissue. This element it is which imponderably arterialises the blood; the nitrogen of the inspiration constitutes the immediate succeeding exspiration.
The oxygenating element promotes the circulation on the same principle that it promotes combustion; its diminutive interstices exclude electric matter, which coagulates, and admits the propelling force, medium of space, which is the only cause of motion, to enter the blood. The oxygenated blood being propelled, or pressed, by the medium of space it includes, from the lungs into the ventricle, the collapse, or systole, takes place, and the blood is forced out of the ventricle, through the auricle, into the aorta, thence through the several branches of the arterial system, to and through the capillaries, into the veins. Thus, from the medium of space within the blood being continuous with the medium of space generally, it is manifest that the blood is circulated not by the systole, but by the general pressure. To produce the systole, there is nothing but the normal pressure on the outside surface of the heart; nor, to lessen the normal pressure on the parietes of the ventricle, is there anything but the arterialising, minus-pressure, imponderable element of the blood just received into the ventricle.
Throughout the entire of the arterial flow, the blood is losing the arterialising minus-pressure matter to the different organs, as the means by which the functional action of each is promoted. Without such means, there is nothing to disturb the equilibrium of pressure on an organ to produce organic motion, action, or function. Hence, it appears, that the use of the inspired oxygen consists in promoting the circulation of the blood and the functional motion or action of the different organs within the frame.
Before entering the veins the blood is fully deoxygenated; within them it acquires gradually electric matter, productive of the livid or coagulating appearance; at the same time the blood-propelling medium is lessening in quantity; but which is compensated in the mucilaginous lining of the veins, which assists the venous flow on the minus-pressure capillary principle; capillary attraction would collapse the vessels. The electric matter collected by the venous blood is got rid of in the lungs, and expired with the nitrogen and a remnant of the oxygenating element of the last inspiration; hence the small portion of carbonic acid gas obtained from the expiration.
After all organic service, the arterialising minus-pressure matter is insensibly transpired, which is inferable from the supply being continued through respiration; which, although constant, yet, from being intermitting, might, perhaps, cause corresponding stoppings in the round of organic action; hence it would seem that, against such intervals or interruptions taking place, the liver has been designed to collect for casual distribution a portion of the same minus-pressure matter. The great surface of the liver may stand comparison with the plate, or cylinder, of the electrifying machine, and the organs as jars which receive electric matter from it, as each stands in need.