High Gas Exchange Research Articles

Ventilation and gas exchange in the mute swan, Cygnus olor

Ventilation and gas exchange have been continuously measured in the mute swan using pneumotachography and breath to breath analysis of the ventilated gas by mass spectrometry combined with blood gas analysis. The breathing frequency was much lower and the tidal volume much higher than values predicted from allometric relations. The breathing cycles typically showed long end-inspiratory breath holding periods. End-tidal P CO 2 and P O 2 were above and below respectively typical end-tidal gas tensions reported earlier in birds. A pronounced positive P CO 2 difference between end-tidal gas and mixed venous blood was present averaging 9.8 mm Hg. The blood-gas values found in the mute swan fall within a range typical of birds. A very low air convection requirement (13.6 ml · ml −1) and high O 2 extraction coefficient (33.0%) indicate a high gas exchange efficiency of the swan lung. The unusually large tidal volumes and the long breath holds succeeding each inspiration are likely contributing factors to the high exchange efficiency. Calculated low values for the blood convection requirement (12.8 ml · ml −1) match the low air convection requirements and result in a ventilation/perfusion ratio near unity ( dot V i / dot Q = 1.06 ).

Analysis of gas exchange between air capillaries and blood capillaries in avian lungs

A number of models is analyzed to study gas exchange between blood capillaries and air capillaries in the avian parabronchial wall when diffusion is the only transport mechanism in the air capillaries. The existing anatomical arrangement of blood capillaries that traverse the periparabronchial tissue from peripherally located arterioles to draining venules at the luminal surface appears to provide a particularly high gas exchange efficiency. Application of the theory to measurements in the hen using histological estimates suggests that substantial concentration gradients exist inside the air capillary gas whose magnitude vary along the parabronchus. Thus at the gas inflow end of the parahronchus the partial pressure drop within the air capillaries could amount, for both O 2 and CO 2, to about 10–15 torr at rest and to 30–40 torr during exercise. Due to the peculiar arrangement of capillary blood flow to the air capillaries the effects of these gradients on gas exchange are very slight during rest. During exercise, however, the diffusional resistance inside the air capillaries may become limiting for the over-all gas exchange, and other mechanisms may be needed to secure respiratory gas transfer.

Respiration of the antarctic copepod, Rhincalanus gigas1

Oxygen consumption and CO2 production of R. gigas were measured during the austral winter. O2 uptake was lower than for low latitude species; the RQ was substantially below 0.7. High lipid content and low respiratory gas exchange in antarctic plankton indicate lipid oxidation for energy, suggesting metabolic adaptation through utilization of NADP‐dependent oxidations. Two periods of reproduction of R. gigas are evident.

Increased alveolar-arterial oxygen difference during simulated high-altitude exposure.

ArticleIncreased alveolar-arterial oxygen difference during simulated high-altitude exposure.J T Reeves, J Halpin, J E Cohn, and F DaoudJ T Reeves, J Halpin, J E Cohn, and F DaoudPublished Online:01 Nov 1969https://doi.org/10.1152/jappl.1969.27.5.658MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByEnhanced muscular oxygen extraction in athletes exaggerates hypoxemia during exercise in hypoxiaRuud Van Thienen and Peter Hespel1 February 2016 | Journal of Applied Physiology, Vol. 120, No. 3Measuring the human ventilatory and cerebral blood flow response to CO2: a technical consideration for the end-tidal-to-arterial gas gradientMichael M. Tymko, Ryan L. Hoiland, Tomas Kuca, Lindsey M. Boulet, Joshua C. Tremblay, Bryenna K. Pinske, Alexandra M. Williams, and Glen E. Foster15 January 2016 | Journal of Applied Physiology, Vol. 120, No. 2End tidal-to-arterial CO2 and O2 gas gradients at low- and high-altitude during dynamic end-tidal forcingMichael M. Tymko, Philip N. Ainslie, David B. MacLeod, Chris K. Willie, and Glen E. Foster1 June 2015 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 308, No. 11Arterial Blood Gases and Oxygen Content in Climbers on Mount EverestNew England Journal of Medicine, Vol. 360, No. 2Transarterial Leakage: A Possible Mechanism of High Altitude Pulmonary Oedema27 May 2008Low Pulmonary Diffusing Capacity in Subjects With Acute Mountain SicknessChest, Vol. 111, No. 1Physical activity at altitude in pregnancySeminars in Perinatology, Vol. 20, No. 4Cardiopulmonary response to acute altitude exposure: Water loading and denitrogenationRespiration Physiology, Vol. 54, No. 3Respiratory and Cardiocirculatory Responses of Acclimatization of High Altitude Natives (La Paz, 3500 m) to Tropical Lowland (Santa Cruz, 420 m)Man in highland ecosystem: effects of exposure to high altitudePulmonary gas exchange, diffusing capacity in natives and newcomers at high altitudeRespiration Physiology, Vol. 34, No. 2The regional distribution of pulmonary blood flow in normal high altitude dwellers at 3650 m (12,200 ft) and in chronic mountain sicknessCardio-respiratory studies in chronic mountain sickness (Monge's syndrome)Dynamic aspects of regulation of ventilation in man during acclimatization to high altitudeRespiration Physiology, Vol. 16, No. 2Pulmonary gas exchange in andean natives at high altitudeRespiration Physiology, Vol. 15, No. 2Adaptation to High AltitudeNew England Journal of Medicine, Vol. 284, No. 23 More from this issue > Volume 27Issue 5November 1969Pages 658-61 https://doi.org/10.1152/jappl.1969.27.5.658PubMed5360439History Published online 1 November 1969 Published in print 1 November 1969 Metrics

Stratified pulmonary blood flow: some consequences in emphysema and pulmonary embolism.

Both ventilation and blood flow in the secondary lobule of the lung are stratified; each unit of lung tissue in the proximal portion of the lobule receives up to four times the blood flow of units in the peripheral portion. Questions of the limiting role of gas diffusion within the small airways become virtually irrelevant in the face of this stratification of function.The central portion of the lobule, with its high ventilation, blood flow, and gas exchange, is very vulnerable; small lesions at this site will produce disproportionately large disturbances of gas exchange and of pulmonary vascular resistance. This may well account for some of the phenomena of conditions such as centrilobular emphysema and pulmonary microembolism.