Temperature and respiratory function in ectothermic vertebrates |
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Authors: | Glauber S.F. da Silva Mogens L. Glass Luiz G.S. Branco |
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Affiliation: | 1. Department of Morphology, Physiology and Pathology, University of São Paulo–USP/FORP, Ribeirão Preto, SP, Brazil;2. Department of Physiology, University of São Paulo–USP/FMRP, Ribeirão Preto, SP, Brazil |
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Abstract: | Pulmonary ventilation is adjusted to maintain balance between O2 demands and CO2 elimination, which is essential for acid–base status in land ectothermic vertebrates. Rising temperatures cause increases in O2 consumption (Q10 effect) and decreases in the O2 affinity of hemoglobin (a rightward shift in the oxygen–hemoglobin dissociation curve). These changes in air-breathing ectotherms are not proportional, i.e., the increased ventilation is relatively smaller than the change in metabolic rate. Therefore, the ratio between ventilation and metabolic rate is reduced, and consequently blood pH changes inversely with temperature. The combination of high temperatures and hypoxia exposure results in an amplified increase of ventilation, which may be explained by the balance between increased O2-demand and decreased O2-supply as well as increased O2-chemoreceptors sensitivity. High temperature also increases pulmonary diffusing capacity. Global warming is expected to have significant impacts on the world’s climate, with temperature changes affecting living organisms, in relation to their physiology and distribution. These physiological mechanisms and their capacity to respond appropriately to temperature illustrate the complexity of the relationship between ambient temperature and the respiratory function in ectothermic vertebrates, which are particularly susceptible to change in their environment. |
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Keywords: | Pulmonary ventilation Gas exchange Blood gases Amphibians Reptiles Lungfish Climate changes |
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