| Ventilatory control in humans: constraints and limitations. | |
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MedLine Citation:
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PMID: 17234715 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Below the lactate threshold ((thetaL)), ventilation (V(E))responds in close proportion to CO(2) output to regulate arterial partial pressure of CO(2) (PaCO2). While ventilatory control models have traditionally included proportional feedback (central and carotid chemosensory) and feedforward (central and peripheral neurogenic) elements, the mechanisms involved remain unclear. Regardless, putative control schemes have to accommodate the close dynamic 'coupling' between and V(E) and V(CO2). Above (thetaL), PaCO2 is driven down to constrain the fall of arterial pH by a compensatory hyperventilation, probably of carotid body origin. When V(E) requirements are high (as in highly fit endurance athletes), V(E) can attain limiting proportions. Not only does this impair gas exchange at these work rates, but there may be an associated high metabolic cost for generation of respiratory muscle power, which may be sufficient to divert a fraction of the cardiac output away from the muscles of locomotion to the respiratory muscles, further compromising exercise tolerance. |
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Authors:
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Susan A Ward |
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Publication Detail:
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Type: Journal Article; Review Date: 2007-01-18 |
Journal Detail:
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Title: Experimental physiology Volume: 92 ISSN: 0958-0670 ISO Abbreviation: Exp. Physiol. Publication Date: 2007 Mar |
Date Detail:
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Created Date: 2007-03-15 Completed Date: 2007-05-10 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9002940 Medline TA: Exp Physiol Country: England |
Other Details:
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Languages: eng Pagination: 357-66 Citation Subset: IM |
Affiliation:
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Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK. s.a.ward@leeds.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Carbon Dioxide
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metabolism Exercise* Exercise Tolerance* Humans Hyperventilation / metabolism, physiopathology Lactic Acid / blood Models, Biological Muscle Contraction* Muscle, Skeletal / metabolism*, physiopathology Oxygen Consumption Pulmonary Gas Exchange Pulmonary Ventilation* Respiratory Center / physiopathology |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide; 50-21-5/Lactic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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