The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
C G Farmer - One of the best experts on this subject based on the ideXlab platform.
-
the pulmonary anatomy of alligator mississippiensis and its similarity to the avian respiratory system
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2012Co-Authors: Kent R Sanders, C G FarmerAbstract:Using gross dissections and computed tomography we studied the lungs of juvenile American alligators (Alligator mississippiensis). Our findings indicate that both the external and internal morphology of the lungs is strikingly similar to the embryonic avian respiratory system (lungs + Air Sacs). We identified bronchi that we propose are homologous to the avian ventrobronchi (entobronchi), laterobronchi, dorsobronchi (ectobronchi), as well as regions of the lung hypothesized to be homologous to the cervical, interclavicular, anterior thoracic, posterior thoracic, and abdominal Air Sacs. Furthermore, we suggest that many of the features that alligators and birds share are homologous and that some of these features are important to the aerodynamic valve mechanism and are likely plesiomorphic for Archosauria. Anat Rec, 2012. © 2012 Wiley Periodicals Inc.
-
On the origin of avian Air Sacs.
Respiratory physiology & neurobiology, 2006Co-Authors: C G FarmerAbstract:For many vertebrates the lung is the largest and lightest organ in the body cavity and for these reasons can greatly affect an organism's shape, density, and its distribution of mass; characters that are important to locomotion. In this paper non-respiratory functions of the lung are considered along with data on the respiratory capacities and gas exchange abilities of birds and crocodilians to infer the evolutionary history of the respiratory systems of dinosaurs, including birds. From a quadrupedal ancestry theropod dinosaurs evolved a bipedal posture. Bipedalism is an impressive balancing act, especially for tall animals with massive heads. During this transition selection for good balance and agility may have helped shape pulmonary morphology. Respiratory adaptations arising for bipedalism are suggested to include a reduction in costal ventilation and the use of cuirassal ventilation with a caudad expansion of the lung into the dorsal abdominal cavity. The evolution of volant animals from bipeds required yet again a major reorganization in body form. With this transition avian Air Sacs may have been favored because they enhanced balance and agility in flight. Finally, I propose that these hypotheses can be tested by examining the importance of the Air Sacs to balance and agility in extant animals and that these data will enhance our understanding of the evolution of the respiratory system in archosaurs.
Patrick J. Butler - One of the best experts on this subject based on the ideXlab platform.
-
The influence of locomotion on Air-sac pressures in little penguins.
The Journal of Experimental Biology, 2001Co-Authors: Dona F. Boggs, Russell V. Baudinette, Peter B. Frappell, Patrick J. ButlerAbstract:Air-sac pressures have been reported to oscillate with wing beat in flying magpies and with foot paddling in diving ducks. We sought to determine the impact on Airsac pressure of wing beats during swimming and of the step cycle during walking in little penguins ( Eudyptula minor). Fluctuations averaged 0.16±0.06 kPa in the interclavicular Air Sacs, but only 0.06±0.04 kPa in the posterior thoracic sac, generating a small differential pressure between Sacs of 0.06±0.02 kPa (means ± S.E.M., N=4). These fluctuations occurred at approximately 3 Hz and corresponded to wing beats during swimming, indicated by electromyograms from the pectoralis and supracoracoideus muscles. There was no abdominal muscle activity associated with swimming or exhalation, but the abdominal muscles were active with the step cycle in walking penguins, and oscillations in posterior Air-sac pressure (0.08±0.038 kPa) occurred with steps. We conclude that high-frequency oscillations in differential Air-sac pressure enhance access to and utilization of the O 2 stores in the Air Sacs during a dive. Summary
-
Differential Air sac pressures in diving tufted ducks Aythya fuligula.
The Journal of Experimental Biology, 1998Co-Authors: Dona F. Boggs, Patrick J. Butler, S E WallaceAbstract:The Air in the respiratory system of diving birds contains a large proportion of the body oxygen stores, but it must be in the lungs for gas exchange with blood to occur. To test the hypothesis that locomotion induces mixing of Air sac Air with lung Air during dives, we measured differential pressures between the interclavicular and posterior thoracic Air Sacs in five diving tufted ducks Aythya fuligula. The peak differential pressure between posterior thoracic and interclavicular Air Sacs, 0.49+/-0.13 kPa (mean +/- s.d.), varied substantially during underwater paddling as indicated by gastrocnemius muscle activity. These data support the hypothesis that locomotion, perhaps through associated abdominal muscle activity, intermittently compresses the posterior Air Sacs more than the anterior ones. The result is differential pressure fluctuations that might induce the movement of Air between Air Sacs and through the lungs during dives.
Franz Goller - One of the best experts on this subject based on the ideXlab platform.
-
Ventilation patterns of the songbird lung/Air sac system during different behaviors.
The Journal of experimental biology, 2013Co-Authors: Rebecca Mackelprang, Franz GollerAbstract:Unidirectional, continuous Airflow through the avian lung is achieved through an elaborate Air sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various Air Sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct Airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of Airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of Air Sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior Air Sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of Airflow and modulation of ventilation in the avian respiratory system.
Kathryn Knight - One of the best experts on this subject based on the ideXlab platform.
-
Air Sacs insufficient for penguin pressure protection
The Journal of Experimental Biology, 2015Co-Authors: Kathryn KnightAbstract:![Figure][1] Emperor penguin at Cape Washington, Antarctica. Photo credit: Paul Ponganis. Anyone who has tried diving will know the uncomfortable feeling of water pressing on their ears. For divers, the knack of holding their noses and exhaling hard to relieve the pressure is second
Dona F. Boggs - One of the best experts on this subject based on the ideXlab platform.
-
The influence of locomotion on Air-sac pressures in little penguins.
The Journal of Experimental Biology, 2001Co-Authors: Dona F. Boggs, Russell V. Baudinette, Peter B. Frappell, Patrick J. ButlerAbstract:Air-sac pressures have been reported to oscillate with wing beat in flying magpies and with foot paddling in diving ducks. We sought to determine the impact on Airsac pressure of wing beats during swimming and of the step cycle during walking in little penguins ( Eudyptula minor). Fluctuations averaged 0.16±0.06 kPa in the interclavicular Air Sacs, but only 0.06±0.04 kPa in the posterior thoracic sac, generating a small differential pressure between Sacs of 0.06±0.02 kPa (means ± S.E.M., N=4). These fluctuations occurred at approximately 3 Hz and corresponded to wing beats during swimming, indicated by electromyograms from the pectoralis and supracoracoideus muscles. There was no abdominal muscle activity associated with swimming or exhalation, but the abdominal muscles were active with the step cycle in walking penguins, and oscillations in posterior Air-sac pressure (0.08±0.038 kPa) occurred with steps. We conclude that high-frequency oscillations in differential Air-sac pressure enhance access to and utilization of the O 2 stores in the Air Sacs during a dive. Summary
-
Differential Air sac pressures in diving tufted ducks Aythya fuligula.
The Journal of Experimental Biology, 1998Co-Authors: Dona F. Boggs, Patrick J. Butler, S E WallaceAbstract:The Air in the respiratory system of diving birds contains a large proportion of the body oxygen stores, but it must be in the lungs for gas exchange with blood to occur. To test the hypothesis that locomotion induces mixing of Air sac Air with lung Air during dives, we measured differential pressures between the interclavicular and posterior thoracic Air Sacs in five diving tufted ducks Aythya fuligula. The peak differential pressure between posterior thoracic and interclavicular Air Sacs, 0.49+/-0.13 kPa (mean +/- s.d.), varied substantially during underwater paddling as indicated by gastrocnemius muscle activity. These data support the hypothesis that locomotion, perhaps through associated abdominal muscle activity, intermittently compresses the posterior Air Sacs more than the anterior ones. The result is differential pressure fluctuations that might induce the movement of Air between Air Sacs and through the lungs during dives.
