caa a22 4500 465826237 CHVBK 20180323112150.0 cr unu---uuuuu 170327e19901101xx s 000 0 eng 10.1007/BF00691722 doi (NATIONALLICENCE)springer-10.1007/BF00691722 Perry S. Fachbereich 7 (Biologie), Universität Oldenburg, D-2900, Oldenburg, Federal Republic of Germany aut Gas exchange strategy in the Nile crocodile: a morphometric study [Elektronische Daten] [S. Perry] Summary: The respiratory surface area (SAR) per kilogram body mass (MB), the harmonic mean thickness of the air-blood barrier (τhtR) in the gas exchange tissue, and the anatomical diffusion factor (ADF=SAR/τhtR per MB) were calculated for four juvenile Nile crocodiles. The ADF of three small specimens (mean MB=3.59 kg) was 625 cm2·μm−1·kg−1. The values varied considerably among individuals and were similar to that of a 5.68-kg specimen (593 cm2·μm−1·kg−1). Only 9% of the ADF is located in the anterior third of the lung, which because of its conical shape makes up only 14 percent of the total lung volume. Particularly in the middle third of the lung, the proximal region near the intrapulmonary bronchus displays a greater ratio of respiratory/non-respiratory surface areas than do more distally located sampling sites. The τhtR is also significantly smaller proximally than distally. The cumulative ADF per unit MB is greater than that previously reported for this species on the basis of overall estimates of SAR and τhtR, but is still less than that of lizards and testudinids. The disposition of ADF between distal air storage region and the intrapulmonary bronchus is consistent with a bidirectional cross-current gas exchange model. Springer-Verlag, 1990 Crocodile nationallicence Lung nationallicence Morphometry nationallicence Strategy nationallicence Evolution nationallicence ADF : anatomical diffusion factor nationallicence % AR : percent of SA included in the effective respiratory zone nationallicence M B : body mass nationallicence NVP : non-ventilatory period nationallicence % P : percent of total lung volume containing parenchyma nationallicence S A : total surface area of intrapulmonary septa nationallicence S ANR : that portion ofS A lying out the effective respiratory zone nationallicence S V : surface-to-volume ratio in the parenchyma nationallicence τhtR : harmonic mean thickness of the air-blood tissue barrier within the respiratory zone nationallicence V P : parenchymal volume nationallicence VP : ventilatory period nationallicence Journal of Comparative Physiology B Springer-Verlag 159/6(1990-11-01), 761-769 0174-1578 159:6<761 1990 159 360 https://doi.org/10.1007/BF00691722 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00691722 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Perry S. Fachbereich 7 (Biologie), Universität Oldenburg, D-2900, Oldenburg, Federal Republic of Germany aut NATIONALLICENCE 773 0- Journal of Comparative Physiology B Springer-Verlag 159/6(1990-11-01), 761-769 0174-1578 159:6<761 1990 159 360 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer