To investigate the mechanical and physiological properties of the cetacean respiratory system, pulmonary mechanics and gas exchange in the bottlenose dolphin were studied. More scarce yet is experimentally derived information on the mechanical properties of the respiratory system and how its physiology is affected by pressure ( Bostrom et al., 2008 Fahlman et al., 2009,, 2006 Falke et al., 1985 Kooyman and Cornell, 1981 Kooyman and Sinnett, 1979,, 1982 Piscitelli et al., 2010). The respiratory physiology of marine mammals has been insufficiently studied and there is a paucity of information related to the mechanical properties of the lung and chest. High pulmonary compliance may be an important component of minimizing transpulmonary pressure gradients ( Fahlman et al., 2014 Leith, 1976,, 1989 Ridgway et al., 1969), and has also been suggested to reduce the risk of elevated blood and tissue N 2 levels, thereby minimizing the risk for DCS ( Ridgway and Howard, 1979 Scholander, 1940). compliance) of the various parts of the respiratory system dictate how pressure affects the distribution of gas between conducting airways and alveolar space ( Bostrom et al., 2008 Fahlman et al., 2009,, 2011 Fitz-Clarke, 2007). Theoretical modeling work indicates that the structural properties (e.g. Scholander (1940) proposed that the conducting airways of marine mammals resist compression, while the alveolar space and chest are flexible, and therefore easily compressed. It has generally been accepted that marine mammals possess physiological and morphological traits that prevent, or reduce, the occurrence of pressure-related pathologies, such as lung squeeze and decompression sickness (DCS). Of all the mammals on earth, marine mammals face the widest range of environmental pressures while foraging. The focus of this work is to illuminate the basic elements of respiratory physiology in cetaceans. One important, yet poorly understood, element of diving capability is the effect of pressure on gas exchange, and thus basic respiratory physiology. If O 2 is not the limiting factor, what other physiological limitations affect the depth and duration of a dive? A multitude of pressure-related variables may impose physiological challenges that limit diving ( Leith, 1989). Studies in both cetaceans ( Ridgway, 1986 Ridgway et al., 1969) and pinnipeds ( Boutilier et al., 2001 Fahlman et al., 2008) suggest that the available O 2 is seldom the limiting factor for the length of a single dive and that CO 2 may be dictating the surface interval between dives. A central concept in breath-hold diving research has been that the available O 2 and its utilization rate during diving determine the length of a single dive. Time underwater needs to be maximized to enhance foraging efficiency however, animals must ultimately return to the surface to exchange metabolic gases. ![]() Our measurements provide novel data for respiratory physiology in cetaceans, which may be important for clinical medicine and conservation efforts.īreath-hold diving mammals live a life of dual constraints. In addition, our custom-made system allows us to approximate end tidal gas composition. The average estimated V̇ O 2 and V̇ CO 2 using our breath-by-breath respirometry system ranged from 0.857 to 1.185 l O 2 min −1 and 0.589 to 0.851 l CO 2 min −1, respectively, which is similar to previously published metabolic measurements from the same animals using conventional flow-through respirometry. The average s C L of dolphins was 0.31☐.04 cmH 2O −1, which is considerably higher than that of humans (0.08 cmH 2O −1) and that previously measured in a pilot whale (0.13 cmH 2O −1). The esophageal pressures indicated that expiration is passive during voluntary breaths, but active during maximal efforts, whereas inspiration is active for all breaths. Our results indicate that bottlenose dolphins have the capacity to generate respiratory flow rates that exceed 130 l s −1 and 30 l s −1 during expiration and inspiration, respectively. The data were used to estimate the dynamic specific lung compliance (s C L), the O 2 consumption rate ( V̇ O 2) and CO 2 production rates ( V̇ CO 2) during rest. We measured esophageal pressures, respiratory flow rates, and expired O 2 and CO 2 in six adult bottlenose dolphins ( Tursiops truncatus) during voluntary breaths and maximal (chuff) respiratory efforts.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |