The Creation of God - Jacob Hartmann (readict TXT) 📗
- Author: Jacob Hartmann
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Blood within the living vessel is a fluid; but when shed, or after the death of the vessels, becomes solid by the process known as coagulation. The average specific gravity of human blood is 1056, varying from 1045 to 1075 within the limits of health. It has an alkaline reaction, which in shed blood rapidly diminishes up to the onset of coagulation.
Blood may, in general terms, be considered as consisting by weight of more than one-third and less than one-half of corpuscles, the rest being plasma, the corpuscles being supposed to retain the amount of water proper to them. Human blood: corpuscles 513, plasma 487. The average quantity of fibrine in the human blood is said to be two per cent.
Composition of serum: In 100 parts there are in round numbers:
Of the proteid substances the great mass consists of the so-called serum-albumen.
Composition of red corpuscles: The red corpuscles contain less water than the serum. In 100 parts of red corpuscle there are:
The solids are almost entirely organic matter, the inorganic salts in the corpuscles amounting to less than 4 per cent. In 100 parts of dried organic matter of the corpuscles of human blood there are:
The blood is distributed as follows in round numbers:
The average proportion of the principal constituents of the blood in 1,000 parts is:
The chemical composition of hæmoglobin is:
The principal organs of respiration consist of larynx, trachea, bronchi, lungs.
The larynx is affixed to the upper end of the windpipe, and is not only the entrance for air into the respiratory organs from the pharynx, but also the organ of voice.
The trachea measures from four inches to four inches and a half in length, and from three-quarters of an inch to one inch in width; but its length and width are liable to continual variations, according to the position of the larynx and the direction of the neck.
The trachea divides into two branches, called bronchi, right and left. The right bronchus, wider and shorter than the left, measuring about an inch in length, passes outwards almost horizontally into the root of the right lung on a level with the fourth dorsal vertebra. The left bronchus, smaller in diameter but longer than the right, being nearly two inches in length, inclines downwards and outwards to reach the root of the right lung, which it enters on a level with the fifth dorsal vertebra—that is, about an inch lower than the right bronchus.
The lungs, placed one on the right and the other on the left of the heart and large vessels, occupy by far the larger part of the cavity of the chest, and during life are always in accurate contact with the internal surface of its walls. Each lung is attached at a comparatively small part of its flattened inner or median surface by a part named the root and by a thin membranous fold, which is continued downwards from it.
The pleuræ are serous membranes forming two shut sacs, quite distinct from each other, which line the right and left side of the thorax, forming by their approximation in the middle line the mediastinal partition, and are reflected each upon the root and over the entire free surface of the corresponding lung.
The lungs. Each lung is irregularly pyramidal or conical, with its base downwards, and one side (the inner) much flattened. The broad concave base is of a semi-lunar form, and rests upon the arch of the diaphragm. The apex is blunt, and reaches into the root of the neck, above the first rib, where it is separated from the first portion of the subclavian artery by the pleural membrane.
The lungs vary much in size and weight, according to the quantity of blood and mucous or serous fluid they may happen to contain, which is greatly influenced by the circumstances immediately preceding death, as well as other causes. The weight of both lungs together, as generally stated, ranges from 30 to 48 ounces, the more prevalent weights being found between 36 and 42 ounces. The proportion borne by the right lung to the left is nearly 22 ounces to 20, taking the combined weight of the two at 42 ounces. The lungs are not only absolutely heavier in the male than in the female, but appear to be heavier in proportion to the weight of the body. The general ratio between the weight of the lungs and body in the adult fluctuates between one to thirty-five and one to fifty.
The average weight in twenty-nine cases, male and female:
The proportionate weight of the lungs to the body is:
The substance of the lungs is of a light porous spongy texture, and when healthy is buoyant in water. Specific gravity, 0.126; deprived of air, 1.056.
When pressed between the fingers, the lungs impart a crepitant sensation, which is accompanied by a peculiar noise, both effects being caused by the air contained in the tissue. On cutting the lung the same crepitation is heard.
The pulmonary tissues are endowed with great elasticity, in consequence of which the lungs collapse to about one-third of their bulk when the thorax is opened.
The root of each lung consists of bronchi, arteries, and veins, together with the nerves, lymphatic vessels, and glands, connected by areolar tissue, and inclosed in a sheath of the pleura.
Respiration consists of an expiration and an inspiration. The air passes in through the nose or mouth, through the larynx, trachea, bronchi, into the lungs.
Inspiration: By the contraction of certain muscles, the cavity of the thorax is enlarged; in consequence the pressure of the air within the lungs becomes less than that of the air outside the body, and this difference of pressure causes a rush of air through the trachea into the lungs until an equilibrium of pressure is established between the air inside and that outside the lungs. This constitutes inspiration.
Expiration: Upon the relaxation of the inspiratory muscles (the muscles whose contraction has brought about the thoracic expansion), the elasticity of the chest walls and lungs, aided by the contraction of certain muscles and other circumstances, causes the chest to return to its original size, or even become smaller. In consequence of this the pressure within the lungs now becomes greater than that outside, and thus air rushes out of the trachea, until equilibrium is once more established. This constitutes expiration.
The inspiratory and expiratory act together form a respiration.
The fresh air introduced into the upper part of the pulmonary passages by the inspiratory movement contains more oxygen and less carbonic acid than the old air previously present in the lungs. By diffusion the new or tidal air, as it is frequently called, gives up the oxygen to, and takes carbonic acid from, the old or stationary air, and thus when it leaves the chest in expiration has been the means both of introducing oxygen into and of removing carbonic acid from it. By this ebb and flow of the tidal air and the diffusion between it and the stationary air, the air in the lungs is being continually renewed, through the alternate expansion and contraction of the chest. In what may be considered normal breathing, the respiratory act is repeated about seventeen times a minute; and the duration of the inspiration as compared with that of the expiration and such pause as exists, is about as ten to twelve.
When the ordinary respiratory movements prove insufficient to effect the necessary changes in the blood, their rhythm and character become changed. Normal respiration gives place to labored respiration, and this in turn to dyspnœa, which unless some restorative event occurs terminates in asphyxia.
Changes of the air in respiration:
1. The temperature of the expired air is variable, but under ordinary circumstances is higher than that of the inspired air.
2. The expired air is loaded with aqueous vapor.
3. The expired air contains about 4 to 6 per cent less oxygen and about 4 per cent more carbonic acid than the inspired air, the quantity of nitrogen suffering but little change. Thus:
While the air in passing in and out of the lungs is thus robbed of a portion of its oxygen, and loaded with a certain quantity of carbonic acid, the blood as it streams along the pulmonary capillaries undergoes important correlative changes. As it leaves the right ventricle it is venous blood of a dark purple or maroon color; when the blood has passed through the lungs and falls into the left auricle, it is arterial blood of a bright scarlet hue. In passing through the capillaries of the body from the left to the right side of the heart, it is again changed from the arterial to the venous condition.
The average composition of this gas in the two kinds of blood is as follows. From 100 volumes may be obtained:
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