Inspiratory aerodynamic valving occurs in the ostrich, Struthio camelus lung: A computational fluid dynamics study under resting unsteady state inhalation

In the avian lung, inhaled air is shunted past the openings of the medioventral secondary bronchi (MVSB) by a mechanism termed 'inspiratory aerodynamic valving' (IAV). Sizes and orientations of the trachea (Tr), syrinx (Sx), extrapulmonary primary bronchus (EPPB), intrapulmonary primary bronchus (IPPB), MVSB, mediodorsal secondary bronchi (MDSB), lateroventral secondary bronchi (LVSB) and the ostium (Ot) were determined in the ostrich, Struthio camelus. Air flow was simulated through computationally generated models and its dynamics analysed. The 'truncated normal model' (TNM) consisted of the Tr, Sx, EPPB, IPPB, MVSB and the Ot. For the 'inclusive normal model' (INM), the MDSB and the LDSB were added. Variations of these models included the 'truncated MVSB1 rotated model' (T(MVSB1)RM), the 'truncated constriction fitted model' (TCFM) and the 'inclusive MVSB1 rotated model' (I(MVSB1)RM). In the TNM, the T(MVSB1)RM and the TCFM, the air flow exited through the MVSB while for the INM and the I(MVSB1)RM, very little of it did: IAV did not occur in the partial models. In the I(MVSB1)RM, rotating the MVSB1 clockwise did not affect IAV. The incomplete models may be faulty because the velocity/pressure profiles in different parts of the interconnected airways form an integrated functional continuum in which different parts of the system considerably impact on each other.

[1]  J J Fredberg,et al.  Inspiratory valving in avian bronchi: aerodynamic considerations. , 1988, Respiration physiology.

[2]  J. Maina,et al.  The lung-air sac system of birds : development, structure, and function , 2005 .

[3]  A. Bethe.  Allgemeines und Vergleichendes , 1925 .

[4]  C. Loudon,et al.  The use of the dimensionless Womersley number to characterize the unsteady nature of internal flow. , 1998, Journal of theoretical biology.

[5]  J Piiper,et al.  Mechanisms of unidirectional flow in parabronchi of avian lungs: measurements in duck lung preparations. , 1972, Respiration physiology.

[6]  W. Calder,et al.  TRACHEAL DEAD SPACE IN THE RESPIRATION OF BIRDS , 1971, Evolution; international journal of organic evolution.

[7]  K. Schmidt-Nielsen,et al.  TEMPERATURE REGULATION AND RESPIRATION IN THE OSTRICH , 1969 .

[8]  W. Bock,et al.  Reference list of the birds of the world , 1975 .

[9]  E. Hazelhoff.  Structure and Function of the Lung of Birds , 1951 .

[10]  M. Fedde.  Structure and gas-flow pattern in the avian respiratory system. , 1980, Poultry science.

[11]  H. Vos.  Über den Weg der Atemluft in der Entenlunge , 2004, Zeitschrift für vergleichende Physiologie.

[12]  R. W. Storer.  CHAPTER II – Adaptive Radiation in Birds , 1960 .

[13]  J Piiper,et al.  Direct measurement of the aathway of respired gas in duck lungs. , 1971, Respiration physiology.

[14]  J. Brackenbury.  Corrections to the Hazelhoff model of airflow in the avian lung. , 1979, Respiration physiology.

[15]  A. J. Marshall,et al.  Biology and comparative physiology of birds. , 1962 .

[16]  J. Brackenbury,et al.  Lung-air-sac anatomy and respiratory pressures in the bird. , 1972, The Journal of experimental biology.

[17]  J. Maina,et al.  Inspiratory aerodynamic valving in the avian lung: functional morphology of the extrapulmonary primary bronchus. , 2000, The Journal of experimental biology.

[18]  Brown,et al.  The avian lung: is there an aerodynamic expiratory valve? , 1995, The Journal of experimental biology.

[19]  Prof. Dr. Dr. Hans-Rainer Duncker.  The Lung Air Sac System of Birds , 1971, Ergebnisse der Anatomie und Entwicklungsgeschichte / Advances in Anatomy, Embryology and Cell Biology / Revues d’anatomie et de morphologie expérimentale.

[20]  O. Larsell,et al.  The embryology of the bird's lung. Based on observations of the domestic fowl. Part II , 1916 .

[21]  A. S. King,et al.  Form and Function in Birds , 1981 .

[22]  P Scheid,et al.  Airflow in the avian respiratory tract: variations of O2 and CO2 concentrations in the bronchi of the duck. , 1981, Respiration physiology.

[23]  C. Harrison,et al.  Bird families of the world , 1978 .

[24]  H. Groenewald,et al.  An anatomical study of the respiratory air sacs in ostriches. , 1999, The Onderstepoort journal of veterinary research.

[25]  J J Fredberg,et al.  Bird lung models show that convective inertia effects inspiratory aerodynamic valving. , 1988, Respiration physiology.

[26]  J J Fredberg,et al.  Pressure profiles show features essential to aerodynamic valving in geese. , 1991, Respiration physiology.

[27]  S. Lanyon.  Phylogeny and Classification of Birds. A Study in Molecular Evolution Charles G. Sibley Jon E. Ahlquist , 1992 .

[28]  V. Molony,et al.  Effects of CO2 on pulmonary air flow resistance in the duck. , 1976, Respiration physiology.

[29]  J. Maina,et al.  A qualitative and quantitative study of the lung of an ostrich, Struthio camelus. , 2001, The Journal of experimental biology.

[30]  K Schmidt-Nielsen,et al.  Control of air flow in bird lungs: radiographic studies. , 1981, Respiration physiology.

[31]  J H Brackenbury,et al.  Airflow dynamics in the avian lung as determined by direct and indirect methods. , 1971, Respiration physiology.

[32]  J H Brackenbury,et al.  Physical determinants of air flow pattern within the avian lung. , 1972, Respiration physiology.

[33]  E. Gruson.  Checklist of the birds of the world. , 1976 .

[34]  D. O. Kuethe,et al.  Fluid mechanical valving of air flow in bird lungs. , 1988, The Journal of experimental biology.

[35]  V. Djonov,et al.  Development and spatial organization of the air conduits in the lung of the domestic fowl, Gallus gallus variant domesticus , 2008, Microscopy research and technique.

[36]  D. Farner,et al.  CHAPTER XIX – Energy Metabolism, Thermoregulation and Body Temperature1 , 1961 .

[37]  Bezuidenhout Aj,et al.  An anatomical study of the respiratory air sacs in ostriches , 1999 .

[38]  P. Scheid.  Mechanisms of gas exchange in bird lungs. , 1979, Reviews of physiology, biochemistry and pharmacology.

[39]  J L Lehr,et al.  Inspiratory aerodynamic valving in goose lungs depends on gas density and velocity. , 1987, Respiration physiology.

[40]  M. Fedde.  Relationship of structure and function of the avian respiratory system to disease susceptibility. , 1998, Poultry science.

[41]  F. Jenkins,et al.  An aerodynamic valve in the avian primary bronchus. , 1992, The Journal of experimental zoology.

[42]  K Schmidt-Nielsen,et al.  Bird respiration: flow patterns in the duck lung. , 1971, The Journal of experimental biology.