Oxygenation

“ Secondly, that water possesses oxygene also as a part of its composition, and contains air likewise in its pores; whence the blood of fish receives oxygene from the water, or from the air it contains, by means of their gills, in the same manner as the blood is oxygenated in the lungs of air-breathing animals; it changes its colour at the same time from a dark to a light red in the vessels of their gills, which constitute a pulmonary organ adapted to the medium in which they live. ”

“ The air composed of oxygen and nitrogen—for the nitrogen enters naturally with the oxygen—penetrates into the pulmonary cells, spreads itself through the blood, and is borne through the numberless little capillary vessels. It is in these little vessels that combustion takes place,—that is to say, that the oxygen unites with the carbon and that carbonic acid is formed. This carbonic acid circulates, dissolved in the blood, until it can escape out of it. It is in the lungs that it finds liberty. ”

“ Thus a fire burns the faster the more air is supplied, and the higher the percentage of oxygen in the air. It was for long believed that in the living body also the rate of oxidation must vary according to the oxygen supply. It has been found, however, that this is not the case. Provided that a certain minimum of oxygen is present in the air breathed, or in the blood supplied to the tissues, it is, practically speaking, indifferent whether the oxygen supply be increased or diminished: only a certain amount is consumed. ”

“ Before the blood from the tissues and lungs has time to mix, however, it leaves the ventricle and by a delicate adjustment in the vessels leaving the heart most of the blood containing much oxygen is passed to all the various organs of the body, while the blood deficient in oxygen, but containing a large amount of carbon dioxide, is pumped to the lungs, where an exchange of oxygen and carbon dioxide takes place by osmosis.
In the tissues of the body wherever work is done the process of burning or oxidation must take place, for by such means only is the energy necessary to do the work released. ”

“ If there be one change in the blood to which, more than to any other, the substances which enter it are liable, it is certainly the process of oxidation. Free oxygen is continually entering the blood through the air-cells of the lungs. ”

“ The more fresh air, i.e., the more oxygen we get into our lungs, the more we can contribute to the processes of oxidation in the tissues. When the processes of circulation and of breathing are checked, and when insufficient oxygen is absorbed, we soon see a very important change for the worse in the condition of such persons, as exemplified by cases of heart and lung trouble.
Given the great importance of oxygen, we must try by every means to get as much of it into our lungs as possible; we shall get more of it from air that is not stagnating, but always in circulation. ”

“ Necessity for Respiration.—We have seen that plants and animals need oxygen in order that the life processes may go on. Food is oxidized to release energy, just as coal is burned to give heat to run an engine. As a draft of air is required to make fire under the boiler, so, in the human body, oxygen must be given so that food in tissues may be oxidized to release energy used in work. This oxidation takes place in the cells of the body, be they part of a muscle, a gland, or the brain. ”

“ Then the dark blood goes back to the lungs, and in them it parts with its carbonic acid and water, which escapes as breath. As fast as we breathe out, carbonic acid and water leave the blood; as fast as we breathe in, oxygen enters it. The oxygen is sent out in the arteries to make the rubbish of the body into gas and vapor, so that the veins may bring it back and get rid of it. The burning of rubbish by oxygen throughout our frames is the fire by which our animal heat, is kept up. ”

“ But oxidation is always going on in the body by means of respiration and the circulation of the blood. We shall afterwards find reason to believe, that the oxygen, received from the atmosphere by the lungs, is the cause of animal heat, and probably of animal irritability; and it is perhaps not unreasonable to suppose, that the nervous influence or electricity may be separated by the brain, and sent along the nerves, which seem the most powerful conductors of it, to stimulate the muscles to action. ”

“ The blood goes to the lungs dark in color from its load of waste. It is changed to a bright red by taking up oxygen. Each red blood-corpuscle takes a load of oxygen, carries it to its destination, and gives it to some tissue to be used up in the chemical process of oxidation, upon which depends our life and energy. During the hours of rest the tissues are busy in this process, and during exercise the energy stored up in the tissue-cells is liberated and waste created. ”

“ The cells in the body lead almost a hand-to-mouth existence so far as their oxygen supply is concerned. They are constantly withdrawing oxygen from the tissue fluids surrounding them, and these fluids are just as constantly withdrawing it from the blood; therefore any failure of the blood to be properly supplied with oxygen results very promptly in a condition of oxygen hunger in the cells. This means prompt cutting off of metabolism, since metabolism is a matter of oxidizing fuel, and oxidation cannot go on unless the oxygen is provided. ”

“ Currie, the effects of which are wonderful, but which can only be applied at the commencement of the disease. In all diseases of indirect debility, therefore, it is proper to attempt the introduction of oxygen into the system, by the oxygenated muriate of potash, acid fruits, nitre, &c. I do not think that the inhaling of oxygen gas for a few minutes in the day can do much good; but free ventilation of apartments, and gentle exercise in the open air, are highly useful. ”

“ An increase of oxygen in the air, therefore, or pure oxygen gas, only produces an effect in certain morbid conditions, in cases of difficulty of breathing, or where breathing has been for some time suspended, because an inspiration communicates more oxygen to the blood than breathing ordinary air. A healthy person can, however, without difficulty or injury, compensate for considerable differences, and an increase or decrease of one or two per cent, of oxygen does no harm, for under ordinary circumstances we only inhale one-fourth of the oxygen in the air we breathe ”

“ The change of colour is caused by the loss of oxygen during the passage of the blood through the capillaries, and the absorption of carbon dioxide from the tissues.
The lungs are two of the great purifiers of the blood. As it circulates through them, it gives up the carbon dioxide which it has absorbed, and [Pg 360] receives pure oxygen in exchange. If the air of a room is "foul," the blood does not get the proper amount of oxygen. ”

“ Experimental evidence is strongly in favor of my argument that the chemical purity of the air is of no importance. Analyses show that the oxygen in the worst-ventilated school-room, chapel or theater is never lessened by more than 1 per cent, of an atmosphere; the ventilation through chink and cranny, chimney, door and window, and the porous brick wall, suffices to prevent a greater diminution. So long as there is present a partial pressure of oxygen sufficient to change the hemoglobin of the venous blood into oxyhemoglobin there can arise no lack of oxygen. ”

“ Later it was realized that this slow combustion did not take place in the lungs, or in the blood, but in the [Pg 92] tissues cells themselves and respiration in the chemical sense has come to mean this universal slow combustion in the cells of the body rather than the breathing movements of the lungs themselves. In anaerobic respiration, CO2 is given off, but no oxygen absorbed. In aerobic respiration, oxygen is absorbed and CO2 given off. In addition we know of many substances which oxidize by taking up oxygen without giving off CO2. ”

“ This dissolves in the blood, colouring it a deep purple, and escapes from it when by the action of the heart the black blood is exposed to the action of the air on the surface of the lungs. Now, the office of the air is to supply this oxygen which removes the carbon from the blood. But the air is not pure oxygen. ”

“ Now, what I wish to have you understand by that, is this: that the average man requires about 137,200 cubic inches of oxygen in every twenty-four hours. This is the accepted way of putting it; in reality, he needs the ozone contained in that amount of oxygen. I do not desire that you should receive the impression that the oxygen is not needed for the man, but that the ozone only is required for the continuance of life where there is no action. I may surprise you when I say that each of you draws into your lungs, every day, over seven pounds of oxygen gas, but such is the case. ”

“ Blood supplies the tissues with their plasmodes; a constant supply of oxygenated blood is therefore necessary to the vitality of the tissues. But it is an error to suppose that oxygen is the special stimulus of nerve-centres, or that their activity depends on their oxidation; on the contrary, the deficiency of oxygen or surplus of carbonic acid is that which stimulates. When saturated with oxygen, the blood paralyzes respiration; when some of the oxygen is withdrawn, respiration revives. ”

“ BREATHING. Nature has provided in the air that surrounds the earth a plentiful supply of oxygen, a gas that is essential to the maintenance of human life. Its function lies in replacing carbonic acid, a poisonous gas developed within the body by the breaking down of tissue, and delivered to the lungs in venous blood. In the process of breathing, oxygen is inhaled and appropriated, while carbonic acid is expelled. ”

“ Oxygen has its Limitations.—​We know all about it; what we forget, perhaps, is, that even oxygen has its limitation: nothing can act but where it is, and, waste attends work, hold true for this vital gas as for other matters. Fire and lamp and breathing beings are all consumers of the oxygen which sustains them. What follows? Why, that this element, which is present in the ratio of twenty-three parts to the hundred in pure air, is subject to an enormous drain [Pg 31] within the four walls of a house, where the air is more or less stationary. ”

“ The amount of carbon dioxide normally present in the blood is, at high altitudes, largely removed from the system owing to the enormous volume of air which it is necessary to inhale in order to obtain a sufficient supply of atmospheric oxygen for the re-oxidation of the venous blood. ”