A text book of physiology / by Isaac Ott.

  • Isaac Ott
Date:
1904
Catalogue details

Licence: In copyright

Credit: A text book of physiology / by Isaac Ott. Source: Wellcome Collection.

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    Olein is always found in a fluid state unless the temperature be very low. When the olein ingredients predominate in a body it is then in a liquid state, as in the case of the oils. Olein is found in both animal and vegetable fats, but the vegetable fats are richer in it than the animal. The oils used in food—olive-oil, oil of sweet almonds, etc. —are derived from the vegetable kingdom. Human fat contains about 75 per cent, of olein plus a small quan- tity of fatty acids in a free state. All are soluble in hot alcohol, ether, and chloroform, but insoluble in water. Saponification. When fat is boiled with alcoholic soda or potash, the particles of fat are broken up into a small quantity of glycerin and a larger quan- tity of fatty acid. The fatty acid unites with the soda or potash, form- ing, as a result, soap. This process of soap-forming is known as saponification. Emulsification. If oil and water are well shaken together the fatty particles do not form a part of the water, but are held in suspension and come to the surface in the form of small globules. A mixture of an oil, a soap, and water is spoken of as an emulsion. No emulsion is per- manent, for even in milk, the most perfect of emulsions, the fatty particles in the form of cream rise to the surface in a few hours. Emulsification is a physical or mechanical rather than a chemical change. Both soaps and emulsions are continually being formed in the body during the digestion of fats. PROTEIDS. The principal constituents forming the muscular, nervous, and glandular tissues, as well as the serum, blood, and lymph, are proteids. In normal urine there are found no proteids, or, if any, only traces. In a great measure the various phenomena of life are present and due to the protoplasm in the cells. On analyzing protoplasm chemically its substance is, of course, killed by the reagents used, but there invariably result in the process proteids. Whether the proteids exist as such in the protoplasm or occur only after the death of the proto- plasm has not been fully established, but are believed to be the con- stituents of it. However, none of the phenomena of life occur without their presence. Proteids are very complex, comprising compounds of carbon,
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