Animal physiology / by John G. M'Kendrick.

  • John Gray McKendrick
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Animal physiology / by John G. M'Kendrick. Source: Wellcome Collection.

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    averaging foth of an inch in diameter, which are called the air-cells (fig. 77). If we can conceive a bunch of grapes with its stem and all its minute branches, and the grapes attached to the ends of them, to be hollow, we get a good idea of the mode in which the lung is constructed, except that it does not represent all the sacculation or partitioning of the terminal cells. It is in consequence of the air included in these cells that the lungs have their soft spongy feeling, and crackle when compressed between the fingers. Each lung is invested by its own investing serous membrane, termed the ^pleura^ which serves the double purpose of facilitating the movements necessary in the act of respiration, and in suspending each lung in its proper position. 135. General Description of Process.—The blood is being perpetually changed and driven in a constant current through the lungs by the action of the heart, the venous or impure blood being collected in the right ventricle, and thence con- veyed by the pulmonary artery into the lungs. In these, again, it gives off carbonic acid and aqueous vapour, and absorbs oxygen (as already described) ; and after these changes, it is collected, and returned to the left auricle by four vessels called the pulmonary veins (p. 87). The mode in which the air is renewed in the lungs next Fig. 76-—Diagram shewing a, tra- chea ; b, division of trachea into two bronchi: c, still smaller bron- chi ; substance of the lung. Fig. 77-—Ultimate structure of Lungs: b, small bronchus; c, external aspect; d, internal aspect of cluster of air- cells.
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