The elements of animal physiology / [William Alexander Osborne].

  • Osborne, W. A. (William Alexander), 1873-1967.
Date:
1909
Catalogue details

Licence: In copyright

Credit: The elements of animal physiology / [William Alexander Osborne]. Source: Wellcome Collection.

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    Connective Tissues. The cells in a particular group, relegated to a particular function, could not act properly unless supported and held in position. Moreover, each group must retain its proper place and not be liable to any great alteration in position or shape. We find then that between cell and cell there is always a cementing substance or intercellular substance even when the cells are apparently in close contact. This intercellular substance, though outside the cells, has been derived originally from cells. But such a union is not sufficient for the body’s needs, and thus it comes about that certain tissues are set aside to act in a purely physical manner, to support and bind rhe cells of active tissues together, to hold organs in position, and to give rigidity and elasticity where such is required. Such tissues are connective tissues, and in them we find that the intercellular substance is often in great excess of the cell proper though dependent on the latter, for, if separated from its cell, it undergoes degenerative changes. The cells in connective tissues have no special function to perform, except to nourish and to maintain the physical condition of the tissues; their activities there- fore are small. Fig. 15.— Endothellium. (After Klein.) In fibrous tissue such as we find in tendon (sinew), the intercellular substance is composed of fine fibres which, though readily bent, are ex- tremely tenacious and almost unstretchable. If the fibres are denselv interwoven and spread out to form a flat membrane such a tissue can act as an envelope or tough capsule, as in the eyeball, testis, &c. In bone we find fibrous sheets, some forming a series of tubes one inside the other, some running from one set of tubes to another, and each bolted to its neighbour by fibrous pegs like layers in the sole of a boot. Even this dense and well riveted tissue is not rigid enough for the body’s needs, and so mineral salts, such as calcium and magnesium phosphates, are pre- cipitated through and through the fibrous sheets. The dentine or ivory of teeth is composed of very minute tubes of fbrous tissue which lead from the tooth pulp to the inner side of the enamel, and, like bone, are hardened by deposition of mineral salts.