Buckmaster's Elements of animal physiology / by John Angell.

  • Angell, John
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Buckmaster's Elements of animal physiology / by John Angell. Source: Wellcome Collection.

    357/384 (page 345)
    The epithelial tissues contain neither bloodvessels, nerves, nor lymphatics. A C Fig. 98.—Epithelium Cells. A. Squamotis or scaly epi- thelium. B. Columnar epithelium. C. Ciliated ,, D. Glandular ,, Cilia (from L., cilium, an eyelash) are exceedingly minute, hair-like, vibratory bodies, which form fringe-like processes, attached to the epitheliuin cells that line the surface of the smaller bronchial tubes, the nasal cavities, frontal sinuses (in the skull), lachry77ial ducts, Eustachian tubes, velum palati, fauces, lary7ix, &c. They are somewhat flattened and tapering, and vary from I-13,000th to i-500th of an inch in length. Their functioft is apparently to prevent the accumulation of viscid fluids, and to propel them towards their outlet. The vibratory motion of the cilia is ceaseless during the life of the epithelium, and they continue in rapid vibration some time after the death of the animal.—(See page 212.) Functions of Mucous Membranes.—The mucous membranes line the open cavities of the body, includ- ing the respiratory, alimentary, and urinary cavities and passages. They act — i, defensively, protecting those organs from the effects of friction and the irrita- tion of the atmospheric air and other substances; 2, as organs of secretion, supplying a liquid by which their surfaces are kept continually moist, and by which the fluids necessary to digestion are elaborated from the blood j 3, as organs of excretion, constantly renew- ing and casting off epithelial cells which escape from the system.