. The comparative physiology of respiratory mechanisms. Respiration. Fig. 28. Air bladder of Erythrinus unitaniatus. pneumatic duct, internal ridges enclosing alveolar spaces 1/2. (Carter and Beadle.) gas bladder or any other cavity as an air-breathing organ are first the regular or irregular renewal of the contained air. In a physoclyst fish the swim bladder can never be a respiratory organ, even if the contained oxygen is in times of distress used for metabolic purposes. In physostome fishes mechan- isms must be present for ven- tilating the bladder, and air must actually be
. The comparative physiology of respiratory mechanisms. Respiration. Fig. 28. Air bladder of Erythrinus unitaniatus. pneumatic duct, internal ridges enclosing alveolar spaces 1/2. (Carter and Beadle.) gas bladder or any other cavity as an air-breathing organ are first the regular or irregular renewal of the contained air. In a physoclyst fish the swim bladder can never be a respiratory organ, even if the contained oxygen is in times of distress used for metabolic purposes. In physostome fishes mechan- isms must be present for ven- tilating the bladder, and air must actually be passed in and out. In Polypterus bichir the gas bladder functions as an accessory respiratory or- gan only when the oxygen content of the water is low (Budgett, 1900). The gas mixture expired must contain less O2 and more C02 than the inspired atmospheric air. The difference in C02 is generally much less than the 02 deficit, because CO2 is given off also to the water through the gills and the skin. Anatomically the walls of the cavity must show a re- spiratory epithelium with a dense network of capillaries close to the surface (Carter and Beadle, Fig. 29 a, b, c). In many cases, and probably always, when the gas bladder is the main respiratory or- gan, the internal surface is enlarged by epithelial ridges often forming distinct alveoli (Fig. 28). The older anatomists placed a great deal of reliance on the character of the blood supply as a criterion, an arterial supply being taken to preclude a respiratory function. This has turned out to be a mistake, and the air-breathing organs in fishes are supplied with blood in the most diverse Fig. 29. c. Capillaries in air blad- der alveoli, respiratory epithe- lium. (Carter and Beadle.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Krogh, August, 18
Size: 1729px × 1444px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectrespiration
