scholarly journals The effect of ambient humidity and metabolic rate on the gas-exchange pattern of the semi-aquatic insect Aquarius remigis

2011 ◽  
Vol 214 (7) ◽  
pp. 1086-1091 ◽  
Author(s):  
H. L. Contreras ◽  
T. J. Bradley
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
Aquatic Insect ◽  
Aquarius Remigis ◽  
Ambient Humidity

Fluctuations in O2 stores and gas exchange with passive changes in posture

1975 ◽  
Vol 39 (1) ◽  
pp. 47-53 ◽  
Author(s):  
J. A. Loeppky ◽  
U. C. Luft
Keyword(s):  
Cardiac Output ◽  
Gas Exchange ◽  
Metabolic Rate ◽  
Blood Volume ◽  
Mass Spectrometer ◽  
Rapid Loss ◽  
Pulmonary Capillary ◽  
O2 Transfer

To clarify the role of O2 stores in the fluctuations in VO2 observed with changing posture, O2 intake (Veo2) and pulmonary capillary O2 transfer (Vpco2) were calculated breath by breath with a box-balloon sprometer and mass spectrometer. Changes in O2 stores of the lungs (O2L) and blood (O2b) were computed assuming metabolic rate (Vco2) constant (O2L = Veo2 - Vpco2; O2b = Vpco2 - Vco2). Measurements were made before, during, and after passive tilt to 60 degrees and on return to recumbency after 10 min erect. From supine to upright O2L increased rapidly and O2b dropped slowly, creating a net deficit in Veo2 of 130 ml in 10 min. Return to supine caused rapid loss in O2L and gain in O2b with a net Veo2 excess of 117 ml. Shifts in O2b were 2.5 times greater but opposite to shifts in O2L. Changes in O2b result from shifts in blood volume and flow more than from changes in cardiac output. Refilling of O2b, matching loss while upright, caused transient hypoxia with significant hyperpnea.

scholarly journals Does Amifostine Reduce Metabolic Rate? Effect of the Drug on Gas Exchange and Acute Ventilatory Hypoxic Response in Humans

2015 ◽  
Vol 8 (2) ◽  
pp. 186-195 ◽  
Author(s):  
Jaideep Pandit ◽  
Caroline Allen ◽  
Evelyn Little ◽  
Federico Formenti ◽  
Adrian Harris ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
Rate Effect ◽  
Hypoxic Response

scholarly journals Water Costs of Gas Exchange by a Speckled Cockroach and a Darkling Beetle

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 632
Author(s):  
Waseem Abbas ◽  
Philip C. Withers ◽  
Theodore A. Evans
Keyword(s):  
Body Size ◽  
Gas Exchange ◽  
Metabolic Rate ◽  
Water Loss ◽  
Evaporative Water ◽  
Factors Affecting ◽  
Darkling Beetle ◽  
Terrestrial Insects ◽  
Exchange Patterns ◽  
Respiratory Cost

Respiratory water loss during metabolic gas exchange is an unavoidable cost of living for terrestrial insects. It has been suggested to depend on several factors, such as the mode of gas exchange (convective vs. diffusive), species habitat (aridity), body size and measurement conditions (temperature). We measured this cost in terms of respiratory water loss relative to metabolic rate (respiratory water cost of gas exchange; RWL/V˙CO2) for adults of two insect species, the speckled cockroach (Nauphoeta cinerea) and the darkling beetle (Zophobas morio), which are similar in their mode of gas exchange (dominantly convective), habitat (mesic), body size and measurement conditions, by measuring gas exchange patterns using flow-through respirometry. The speckled cockroaches showed both continuous and discontinuous gas exchange patterns, which had significantly a different metabolic rate and respiratory water loss but the same respiratory water cost of gas exchange. The darkling beetles showed continuous gas exchange pattern only, and their metabolic rate, respiratory water loss and respiratory cost of gas exchange were equivalent to those cockroaches using continuous gas exchange. This outcome from our study highlights that the respiratory water cost of gas exchange is similar between species, regardless of gas exchange pattern used, when the confounding factors affecting this cost are controlled. However, the total evaporative water cost of gas exchange is much higher than the respiratory cost because cuticular water loss contributes considerably more to the overall evaporative water loss than respiratory water. We suggest that the total water cost of gas exchange is likely to be a more useful index of environmental adaptation (e.g., aridity) than just the respiratory water cost.

Metabolic rate and respiratory gas-exchange patterns in tenebrionid beetles from the Negev Highlands, Israel

2002 ◽  
Vol 205 (6) ◽  
pp. 791-798 ◽  
Author(s):  
Frances D. Duncan ◽  
Boris Krasnov ◽  
Megan McMaster
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
Water Loss ◽  
Activity Patterns ◽  
High Water ◽  
Standard Metabolic Rate ◽  
Active Species ◽  
Habitat Associations ◽  
Diel Activity ◽  
Water Vapour Pressure

SUMMARY This study correlates the pattern of external gas exchange with the diel activity of nine species of tenebrionid beetle from the Negev Desert, Israel. The study species are active throughout the summer months when daytime temperatures are high and no rain falls. There were no differences in standard metabolic rate, determined by flow-through respirometry, among the nine species. All the nocturnally active beetles exhibited a form of continuous respiration, whereas the two diurnally active and one crepuscular species exhibited a cyclic form of respiration referred to as the discontinuous gas-exchange cycle (DGC). The DGCs recorded have a long flutter period consisting of miniature ventilations, and 29–48 % of the total CO2 output occurred during this period. In this study, the flutter period played an important role in the modulation of metabolic rate, in contrast to other studies in which the burst period has been shown to be important. We suggest that the long flutter period is important in reducing respiratory water loss in arid-dwelling arthropods. This study lends support to the hypothesis that discontinuous gas exchange is important in reducing respiratory water loss from beetles that need to minimise dessication because of the high water vapour pressure gradient they experience. If the use of underground burrows were responsible for the evolution of discontinuous gas exchange, then we would expect all nine tenebrionid species to use DGCs since both the nocturnally and diurnally active species bury in the sand during periods of inactivity. We conclude that the activity patterns of the beetles are more important than their habitat associations in designating the type of respiration used.

scholarly journals Respiratory gas exchange at lungs, gills and tissues: mechanisms and adjustments.

1982 ◽  
Vol 100 (1) ◽  
pp. 5-22 ◽  
Author(s):  
J Piiper
Keyword(s):  
Gas Exchange ◽  
Metabolic Rate ◽  
High Energy ◽  
Tissue Level ◽  
High Energy Phosphates ◽  
Amphibian Skin ◽  
Physiological Adjustments ◽  
Pressure Changes ◽  
Hydrolysis Of ◽  
O2 Debt

(1) A general model for external gas exchange organs of vertebrates is presented, in which the main parameters are the ventilatory, diffusive and perfusive conductances for O2 and CO2. The relevant properties of the external medium (air or water) and of the internal medium (blood) are analysed in terms of capacitance coefficients (effective solubilities) for O2 and CO2. The models for the main types of gas exchange organs (fish gills, amphibian skin, and avian and mammalian lungs) are compared in terms of their intrinsic gas exchange efficacy. The adjustments to increased metabolic rate or to hypoxia are achieved by increasing the conductances. (2) The gas exchange at tissue level is analysed using the Krogh cylinder and a simplified model containing a diffusive and a perfusive conductance. The adjustments to increased load (exercise, hypoxia) consist in both increased local blood flow and in improvement of diffusion conditions (enlargement and recruitment of capillaries). (3) Some particular features of respiration in transitional (unsteady) states, such as occurring at the beginning of exercise and of hypoxia, are examined. The additional physical variables are the O2 (and CO2) stores acting according to their capacitances and partial pressure changes. Delayed increase in O2 uptake at the beginning of exercise is due to the limited speed of physiological adjustments. The ensuing O2 debt is energetically covered by anoxidative energy releasing processes (hydrolysis of high-energy phosphates and anaerobic glycolysis). Finally, the reduction of metabolic rate as adjustment to hypoxia is discussed.

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