Licence: Public Domain Mark
Credit: A text book of physiology / by William Rutherford. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![on the effect of anaesthetics on nerve cells is obvious. Oxygen is con- sumed by contracting cilia. Kiihne pi-oved this by placing living ciliated epithelium in a solution of oxyhemoglobin, and finding that after some time the hajmoglobin was reduced, owing to removal of its loosely com- bined oxygen. Oxygen is indispensable for the maintenance of the movement, for although the cilia may continue to contract for a consider- able time in its absence, they certainly become paralysed unless it is supplied. Carbonic acid first accelerates, and then arrests, the movement. The acceleration is IDrobably owing to its exciting the cell, while the an-est is douVitless owing to a poisonous effect. A very dilute solution of caustic potash accelerates the motion when the cilia are becoming sluggish, and it may even recall the movement after it has ceased (Virchow). Dilute acids, and dilute alcohol, have also a reviving power. Observations on the effects of induced and of galvanic electricity have led to no perfectly clear results. Functions of Cilia.—In the respiratory passages cilia discharge the important function of moving mucus out of the lungs into the pharynx, where it is swallowed.- Cilia also remove mucus from the tympanum, and impel it into the pharynx ; whilst in the Fallopian tube they aid in the downward passage of the ovum towards the uterus. The Energy of CiUanj Motion is, as Wyraan flist showed, by no means inconsiderable. Elaborate experiments have been made bj^ Bowditch (Oj). 47, August 10, 1876) on this subject. His e.\])eriments were performed hy removing the ciliated membrane of the frog's nioutli, and fixing it on a plate of glsiss, with the ciliated sm-face free. The prepara- tion was then jdaced on an inclined plane, dilferent weights were ajiplied to the ciliated surface, and the extent to which in a given time tlie cilia carried a given weight up the inclined plane was observed. He in this way ascertained that the cilia on 1 square centimeter of mucous membrane can perform in one minute 6'8 grammillimoters of work ; that is, they can do work e(|uivalent to raising 6'8 grammes to the height of 1 millimeter in one minute. He calculates that in one minute they could lift their own weight to. the height of 4 'SS meters. AVhon compared wth the work of a muscle, this is a relatively small amount of work for a contractile tis.sue to perform. It is little more than T)V of the working power of tlie heart, which in one minute does work equal to lifting its own weight to the height of 150 meters (Scliift, Op. 48, i. p. 24). GLANDULAR EPITHELIUM. Epithelium is the secreting element in all glands save blood-glands. The term spheroidal has been applied to glandular epithelium, but the cells are usually polygonal—rarely si^heroidal. They are nucleated protoplasts, usually without an envelope, so that the products of secretion readily escape. If chalice cells are to be regarded as unicellular glands (p. 68), they have an envelope, but there is a free openiug at one end of the cell to allow the secretion to escape. Many of the substances found in secretions are produced within the gland cells ; thus pepsin is formed by the gastric glands ; tlie bile acids produced by the liver are not found in the blood, but are elaborated from the proteicls of the blood by the glands. On the other hand, in such a gland as the kidney, the great function of the cells appears to be to withdraw from the blood matters already formed,— urea, etc. Modifications of E])itheliwm,. Epithelial cells may be variously arranged and variously modified, to constitute hair, nail, hoof, horn, feather, fibres of the crystalline lens, enamel](https://iiif.wellcomecollection.org/image/b21981747_0084.jp2/full/800%2C/0/default.jpg)
