Document Detail


High fliers: the physiology of bar-headed geese.
MedLine Citation:
PMID:  20116442     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Up to half the world's population of bar-headed geese (Anser indicus) migrate between central Asia and India and fly between 5000 m and 9000 m above sea level as they cross the Himalayas. The partial pressures of oxygen at these altitudes are, respectively, about 50% and 30% those at sea level. Flapping flight is energetically expensive, so how are bar-headed geese able to migrate at such altitudes? The haemoglobin of bar-headed geese has a greater affinity for oxygen than those of lowland birds, and birds are able to hyperventilate to a greater extent than mammals during severe hypoxia. Together, these mean that the concentration of oxygen in the arterial blood at a given altitude is greater in bar-headed geese than in lowland birds and mammals. The low partial pressure of CO(2) in arterial blood (hypocapnia) that accompanies hyperventilation does not cause reduction of cerebral blood flow in birds as it does in mammals, thus there is greater oxygen delivery to the brain in hypoxic birds, including bar-headed geese, than in mammals. Captive bar headed geese could not maintain elevated aerobic metabolism during exercise at a simulated altitude of 8500 m and their cardiac stroke volume was much lower than that during exercise at sea level. This suggests that if some individuals of this species of geese do really manage to fly over Mt Everest, they may only do so if they receive assistance from vertical air movements, for example from lee waves downwind from the mountains.
Authors:
Patrick J Butler
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-01-28
Journal Detail:
Title:  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology     Volume:  156     ISSN:  1531-4332     ISO Abbreviation:  Comp. Biochem. Physiol., Part A Mol. Integr. Physiol.     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-05-17     Completed Date:  2010-11-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9806096     Medline TA:  Comp Biochem Physiol A Mol Integr Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  325-9     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier Inc. All rights reserved.
Affiliation:
Centre for Ornithology, School of Biosciences, University of Birmingham, Birmingham, B152TT, England, UK. p.j.butler@bham.ac.uk
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MeSH Terms
Descriptor/Qualifier:
Altitude*
Animals
Atmosphere / chemistry
Biological Transport
Carbon Dioxide / blood
Cerebrovascular Circulation / physiology
Flight, Animal / physiology*
Geese / blood,  physiology*
Hyperventilation / blood
Hypocapnia / blood
Mammals / physiology
Oxygen / analysis,  blood
Oxygen Consumption / physiology*
Partial Pressure
Pulmonary Ventilation / physiology
Grant Support
ID/Acronym/Agency:
BB/F015615/1//Biotechnology and Biological Sciences Research Council
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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