The laws and mechanics of circulation, with the principle involved in animal movement . cumstance which is also proven by exciting the bronchialmucous membrane artificially, when cough is readily it would also explain the short, energetic inspiration?which precedes cough, since this would have the effect of EXPELLING ALVEOLAK COLLECTIONS. 101 aspirating the collections in the alveoli, while the snddenforced expiratory effort, which follows immediately after,should have the effect of expelling them from the body. Theanatomical dispositions are very perfect; could not be better. For
The laws and mechanics of circulation, with the principle involved in animal movement . cumstance which is also proven by exciting the bronchialmucous membrane artificially, when cough is readily it would also explain the short, energetic inspiration?which precedes cough, since this would have the effect of EXPELLING ALVEOLAK COLLECTIONS. 101 aspirating the collections in the alveoli, while the snddenforced expiratory effort, which follows immediately after,should have the effect of expelling them from the body. Theanatomical dispositions are very perfect; could not be better. For example, the bronchi are surrounded by neighboringalveoli, which are not only in contact with the tubing, but areactually incorporated in the walls for compelling them to re-spond to the movements in the tubing during respiration ( ,f, <z, b). The effect of this arrangement is sufficiently ob-vious. Thus, when the bronchi expand during inspiration,they push against the neighboring alveoli ; at the same timethey develop a suction force within themselves for aspirating b Fig. 38.—Portion of a transverse sectioD of a pigs bronchial twig, .04 millim. in diam-eter, magnified 2^.—Schulze. a, outer fibrous layer; b, muscular layer ; c, innerfibrous layer ; d, epithelial layer ; /, one of the neighboring alveoli. the contents ; hence a pulling and pushing force combine forexpelling the alveolar collections during inspiration; whileduring expiration the sudden contraction which sets in, andthe coincident narrowing this produces in the lumen of thetubes, increases the friction of the air against the membranesfor compelling the secretions out of the body, which is finallyaccomplished by cough, in which the mucous surface is sweptas with a broom by the out-rushing air, under the energeticaction of the abdominal muscles and the pressure of the visceraagainst the bases of the lungs which this produces, the sidesof the chest, of course, contracting simultaneously. And the 102
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Keywords: ., bookcentury1800, bookde, booksubjectblood, booksubjectrespiration
