Licence: Public Domain Mark
Credit: Outlines of human pathology / by Herbert Mayo. Source: Wellcome Collection.
Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.
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![one of which consists in dilatation of the smaller air-tubes, the other in rupture of the pulmonary cells, and diffusion of the air throuo;h the interstitial cellular membrane. a. Dilatation of the smaller air-tubes is liable to be pro- duced by any cause which obstructs them. The ordinary cause is a glutinous secretion attending one or other of the forms of bronchial inflammation, which will afterwards be noticed. When the outlet of a lobule of the lung, as it often happens, is blocked up by a little pearl-like concretion of tough mucus, each expiratory effort in coughing com- presses the vesicular structure, and strains the air-tube into which it opens; both are liable to be injured, the air-cells to become larger and irregular, the bronchial tube to be di- lated. The enlargement of the air-cells and bronchial tubes takes place at the expense of the blood-vessels, which, being habitually compressed, some of them are obliterated, and most are contracted to less than their natural calibre. An emphysematous lung, when examined, appears to be less vascular than another : it is less crepitant, more elastic, and does not collapse. The surface is often irregular, from the dilatation or rupture of the vesicular structure having pro- duced bullae of different sizes immediately below the pleura, [w. 74. 75.] When the circulation is tranquil, the atmosphere dry and of a moderate temperature, and bronchitis not present, the patient labouring under vesicular emphysema often breathes freely. But when any of these conditions are reversed, a paroxysm of embarrassed respiration, or asthma supervenes. The sign of the disease obtained on percussion is, an un- usually loud drum-like sound; — on auscultation, the ab- sence of the ordinary vesicular murmur. b. Interlobular emphysema is liable to be produced by the giving way of dilated air-passages. Or it may likewise be the result of rupture of the air-cells in healthy lungs through violent muscular exertion, as during labour : in the latter case, the air has been known to make its way into the cel- lular membrane of the neck and chest. This kind of em- physema disappears readily through the absorption of the air which has escaped.](https://iiif.wellcomecollection.org/image/b21066735_0537.jp2/full/800%2C/0/default.jpg)
