Document Detail


Physiology of diving of birds and mammals.
MedLine Citation:
PMID:  9234967     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This review concentrates on the physiological responses, and their control, in freely diving birds and mammals that enable them to remain submerged and sometimes quite active for extended periods of time. Recent developments in technology have provided much detailed information on the behavior of these fascinating animals. Unfortunately, the advances in technology have been insufficient to enable physiologists to obtain anything like the same level of detail on the metabolic rate and physiological adjustments that occur during natural diving. This has led to much speculation and calculations based on many assumptions concerning usable oxygen stores and metabolic rate during diving, in an attempt to explain the observed behavior. Despite their shortcomings, these calculations have provided useful insights into the degree of adaptations of various species of aquatic birds and mammals. Many of them, e.g., ducks, smaller penguins, fur seals, and Weddell seals, seem able to metabolize aerobically, when diving, at approximately the same (if not greater) rate as they do at the surface. Their enhanced oxygen stores are able to support aerobic metabolism, at what would not be considered unusually low levels, for the duration of the dives, although there are probably circulatory readjustments to ensure that the oxygen stores are managed judiciously. For other species, such as the larger penguins, South Georgian shag, and female elephant seals, there is a general consensus that they must either be reducing their aerobic metabolic rate when diving, possibly by way of regional hypothermia, and/or producing ATP, at least partly, by anaerobiosis and metabolizing the lactic acid when at the surface (although this is hardly likely in the case of the female elephant seals). Circulation is the proximate regulator of metabolism during aerobic diving, and heart rate is the best single indicator of circulatory adjustment. During voluntary dives, heart rates range from extreme bradycardia to well above resting, reflecting metabolic performance. Efferent cardiac control is largely parasympathetic. Reflex cardiorespiratory responses are modulated by conditioning and habituation, but reflexes predominate during extended dives and during recovery, when gas exchange is maximized.
Authors:
P J Butler; D R Jones
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.; Review    
Journal Detail:
Title:  Physiological reviews     Volume:  77     ISSN:  0031-9333     ISO Abbreviation:  Physiol. Rev.     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-08-15     Completed Date:  1997-08-15     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0231714     Medline TA:  Physiol Rev     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  837-99     Citation Subset:  IM; S    
Affiliation:
School of Biological Sciences, The University of Birmingham, Edgbaston, United Kingdom.
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphate / metabolism
Animals
Behavior, Animal / physiology*
Birds / physiology*
Cardiovascular Physiological Phenomena
Diving / physiology*
Ducks
Mammals / physiology*
Oxygen / metabolism
Respiration / physiology
Seals, Earless
Time Factors
Chemical
Reg. No./Substance:
56-65-5/Adenosine Triphosphate; 7782-44-7/Oxygen

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


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