This section is from the book "Human Physiology For The Use Of Elementary Schools", by Charles Alfred Lee. Also available from Amazon: Human Physiology, for the Use of Elementary Schools.
1. By the chemical composition of the body, is meant those ultimate elements of which it is made ; such as oxygen, carbon, hydrogen, and azote. By the organic composition, we mean the proximate elements, which are formed out of these by the power of the living principle ; such as albumen, fibrin, gelatine, etc.
2. The ultimate elements of animal matter have been divided into non metallic, and metallic substances ; the former consisting of oxygen,, hydrogen, carbon, azote, phosphorus, sulphur, chlorine, and fluorine; the latter, 1, the bases of the alkalies, viz., potassium, sodium, and calcium; 2, the bases of the earths, magnesium, silicium, and aluminum; 3, the ponderous metals, iron, manganese, and copper.
Of the first class, or the non metallic substances, oxygen, hydrogen, carbon and azote exist in much the largest proportion, and are in fact the only essential elements of animal matter.
3. All the solids and fluids of the body contain oxygen. It is essential to all the proximate elements. United with hydrogen, it forms water, which is calculated to constitute nine tenths of the whole weight of the body. In union with carbon, it forms carbonic acid, which exists in the blood, and is thrown out by the lungs and skin.
3. Oxygen forms with phosphorus, phosphoric acid, which with lime constitutes the earthy portion of the bones ; it also exists in some of the secretions. In union with their metalic bases, it forms potash, soda, and lime. It also is a constituent part of albumen, fibrin, gelatine, and mucus. Oxygen is derived partly from the air we breathe, and partly from our food and drinks. It is given off in all the secretions and excretions. The air contained in the swimming bladder of fishes, is pure oxygen.
4. Hydrogen exists in all the fluids and most of the solids, constituting as it does one element of water. In venous blood, it exists in a larger proportion than in arterial blood, which contains more oxygen. In the bile, it is very abundant, and in fat and oil, is one of the essential elements. It is this gas which often causes so much distress in a weak state of the stomach. Hydrogen is introduced into the system by means of food and drinks, and is discharged in the same manner as oxygen.
5. Carbon abounds in the vegetable as well as animal kingdom. In oil, fat, albumen, gelatine, fibrin, and mucus, it always forms a part. In bile, and in venous blood, it exists largely. If we burn a piece of animal substance, what is left is found to be chiefly carbon. We obtain it from our food, and give it off by breathing and the secretions. It is carbon that makes venous blood darker than arterial, and the change from purple to bright crimson which takes place in the lungs, is supposed to be owing chiefly to the fact, that the excess of carbon contained in venous blood is discharged by respiration.
6. Azote exists in large quantities in all animal matter. It also exists to some extent in a few vegetables, but it is an essential element in animal substances. It is more abundant in fibrin, of which the muscular flesh is chiefly formed, than in any other portions of the body, though it is found in the brain and nerves. The peculiar smell of burning animal matter is owing to azote. When animal substances putrefy, it combines with hydrogen, and forms ammonia or hartshorn.
7. Azote is chiefly taken into the system by means of animal food. It is also taken into the blood by respiration, as it forms a constituent part of the atmosphere. This, however, is denied by some chemists. It is discharged from the system in the same manner as oxygen, hydrogen, and carbon ; though chiefly through the kidneys.
8. Phosphorus exists both in animal and vegetable substances. Nearly every part of animal bodies contain it, though it is found more abundantly in the bones. It generally exists in combination with oxygen, forming phosphoric acid. It is discharged mostly through the kidneys. The spontaneous combustion of human bodies, of which we have some well attested cases of drunkards, is supposed to be owing to an accumulation of phosphorus in the system, from some unknown cause.
9. Sulphur is always united, in animal substances, with other elements, as soda and potash. It is found in albumen, in the hair and nails, and in muscular flesh. It is given off by the intestines and by the skin.
10. Chlorine is found in most of the animal fluids combined with hydrogen. This forms hydrochloric acid. In the blood it is combined with soda and potash. It is found also in the gastric juice, in sweat, milk, saliva, etc.
11. Potash exists more abundantly in plants than in animals. It is, however, contained in the blood, bile, urine, sweat, milk, etc.
12. Soda is more abundant in animals than plants. It exists in the same fluids in which potash is found ; also in bones and muscular flesh. It is always combined with some acid.
13. Lime forms a large part of the bones, in union with phosphoric or carbonic acid. Silex exists in human hair, and in some of the secretions. Magnesia is contained in bones, and in some animal fluids, as milk. It is also found in the brain. Iron forms the colouring principle of the red globules of the blood, and is therefore pretty extensively found in animal bodies.
14. The organic or proximate elements of the body are formed from the ultimate elements already described. We cannot explain their formation on any chemical or mechanical laws, but refer them solely to the influence of the vital forces.
15. These proximate elements are mostly formed from a combination of oxygen, carbon, hydrogen, and azote, and are divided into two classes, acids and oxyds.
16. The acids found in the human system are the acetic, oxalic, the benzoic, and the uric. The three first are also found in the vegetable kingdom, and are composed of oxygen, hydrogen, and carbon. When these organic elements are made of three simple elements, they are called ternary oxyds; such are sugar, resin, and the fixed and volatile oils.
17. Milk contains a considerable quantity of sugar. It can be obtained from whey by evaporating it slowly to the consistence of a syrup, and then allowing it to cool. It may then be purified by the white of an egg, or albumen, and crystalized again. It has a different taste from the sugar of the cane.
18. The bile contains a peculiar resin. Fat and the marrow of the bones contain fixed oils. But the most important compounds of the body are albumen, fibrin, gelatine, mucus,. and osmazome.
19. Albumen exists in the body, both in a solid and fluid form. Combined with water it forms the white of eggs; hence its name. It exists most abundantly in the serum, but is found in all the fluids of the body. It is transparent, without colour, taste, or smell, and coagulates by heat, acids, and alcoho.
20. Solid albumen is also a white and tasteless substance. It forms the basis of the nerves and brain, and is contained in the skin, hair, nails, glands, and vessels. Tumours and wens are mostly composed of albumen. It is composed of
Carbon 52 parts; Oxygen 23 parts; Hydrogen 7 parts; Azote 15 parts.
21. Fibrin is the basis of muscular flesh ; and enters largely into the formation of the blood, chyle, and lymph. It is owing to the presence of fibrin that blood coagulates when removed from the body. Fibrin is a solid, white substance, of a fibrous structure, destitute of smell and taste, and insoluble in water.
22. Fibrin may be obtained by washing the thick part of the blood with cold water, and thus separating the colouring matter, or the red globules. It differs from albumen by possessing the property of coagulating at all temperatures. Fibrin is composed of Carbon 43 parts ; Oxygen 19 parts ; Hydrogen 7 parts; Azote 19 parts. It contains more azote and less oxygen than albumen.
23. Gelatine is found in none of the fluids of the human body. It is, however, found in nearly all the solids. It is known from all the other animal principles by its readily dissolving in warm water, forming a kind of jelly. When dry, it forms a hard, shining, brittle substance, called glue. This is mostly prepared from the skins and hoofs of animals, by boiling them in water, and then evaporating the solution. Isinglass is obtained from the sounds of the sturgeon, and is a very pure gelatine.
24. Gelatine exists largely in the skin, cartilages, ligaments, tendons, and bones, and it forms the basis of the cellular tissue. As it does not exist in the blood, it is probably a modification of albumen. It is composed of Carbon 47 parts ; Oxygen 27 parts ; Hydrogen 7 parts ; Azote 16 parts.
25. It appears that gelatine contains less carbon than albumen, by 5 or 6 per cent., and a larger proportion of oxygen in the same ratio. Now, if we suppose, that near the skin, and in the various tissues of the body, the albumen of the blood gives off a portion of its carbon, a part of which is taken up by the veins, and a part thrown off by the skin, lungs, and various secretions, we shall see how gelatine may be formed out of albumen.
26. Osmazome is an element which exists in all the animal fluids, and in some of the solids, as the brain and muscular fibre. It is of a reddish brown colour, of an aromatic smell and agreeable taste. It is this which gives the strong flavour of roasted meat, and the peculiar taste of the various kinds of animal food. It is supposed to be tonic and stimu. lating, but to possess no nutritive properties.
27. Mucus is that bland fluid which moistens the surface of all the mucous membranes. In some of the hard parts of the body, which are destitute of sensibility, it is found to exist in considerable quantities, as in the nails, hair, and cuticle of man, and in the scales, feathers, and wool of different animals. That part of the skin called rete mucoscum, is supposed to be compacted mucus. Mucus is transparent, has no colour or taste, and has a ropy and viscid consistence. When dry, it is insoluble in water. It contains much azote.
28. There are some other substances found in the human body, such as caseine, or that principle of the milk which forms the basis of cheese, curd, etc. ; but they are not of sufficient importance to need a particular description.
What is meant by the chemical composition of the body ? What are some of the ultimate elements ? What are some of the proximate elements ? How have the ultimate elements been divided ? Is oxygen essential to all the proximate elements ? What is said of hydrogen ?-Of carbon ?-Of Azote ? How do oxygen, hydrogen, and azote get into the system ? Is phosphorus found in animal bodies ? What other elements are met with in animals ? How are the organic elements of the body formed ? How divided ? What acids are found in animal bodies ? What are the most important compounds in the body ? What is said of albumen ? In what is it found ? What is fibrin the basis of? How may it be obtained from blood ? Of what is it composed ? Where is gelatine found in the animal body? How known from the other animal principles ? What does it form when dried ? Of what is glue prepared ? In what does gelatine exist ? How may we account for the productions of gelatine ? What is osmazome ? What peculiar properties has it ? What is mucus ? Where found, what is its use ? Are any other substances found in the human body ?
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