Pressure cycles and the water economy of insects

1988 ◽  
Vol 318 (1190) ◽  
pp. 377-407 ◽  
Keyword(s):  
Body Temperature ◽  
Water Exchange ◽  
Vapour Phase ◽  
The Body ◽  
Tracheal System ◽  
Water Economy ◽  
Insect Wings ◽  
Pressure Cycle ◽  
Respiratory Gases

Water exchange between insects and their environment via the vapour phase includes influx and efflux components. The pressure cycle theory postulates that insects (and some other arthropods) can regulate the relative rates of influx and efflux of water vapour by modulating hydrostatic pressures at a vapour-liquid interface by compressing or expanding a sealed, gas-filled cavity. Some such cavities, like the tracheal system, could be compressed by elevated pressure in all or part of the haemocoele. Others, perhaps including the muscular rectum of flea prepupae, could be compressed by intrinsic muscles. Maddrell Insect Physiol . 8, 199 (1971)) suggested a pressure cycle mechanism of this kind to account for rectal uptake of water vapour in Thermobia but did not find it compatible with quantitative information then available. Newer evidence conforms better with the proposed mechanism. Cyclical pressure changes are of widespread occurrence in insects and have sometimes been shown to depend on water status. Evidence is reviewed for the role of the tracheal system as an avenue for net exchange of water between the insect and its environment. Because water and respiratory gases share common pathways, most published findings fail to distinguish between the conventional view that the tracheal system has evolved as a site for distribution and exchange of respiratory gases and that any water exchange occurring in it is generally incidental and nonadaptive, and the theory proposed here. The pressure cycle theory offers a supplementary explanation not incompatible with evidence so far available. The relative importance of water economy and respiratory exchange in the functioning of compressible cavities such as the tracheal system remains to be explored. Some further implications of the pressure cycle theory are discussed. Consideration is given to the possible involvement of vapour-phase transport in the internal redistribution of water within the body. It is suggested that some insect wings may constitute internal vapour-liquid exchange sites, where water can move from the body fluids to the intratracheal gas. Ambient and body temperature must influence rates of vapour-liquid mass transfer. If elevated body temperature promotes evaporative discharge of the metabolic water burden that has been shown to accumulate during flight in some large insects, their minimum threshold thoracic temperature for sustained flight may relate to the maintenance of water balance. The role of water economy in the early evolution of insect wings is considered. Pressure cycles might help to maintain water balance in surface-breathing insects living in fresh and saline waters, but the turbulence of the surface of the open sea might prevent truly marine forms from using this mechanism.

Dynamics of tracheal compression in the horned passalus beetle

2013 ◽  
Vol 304 (8) ◽  
pp. R621-R627 ◽  
Author(s):  
James S. Waters ◽  
Wah-Keat Lee ◽  
Mark W. Westneat ◽  
John J. Socha
Keyword(s):  
Dynamical Behavior ◽  
The Body ◽  
Reverse Direction ◽  
Effective Diameter ◽  
Contrast Imaging ◽  
Tracheal System ◽  
Tracheal Compression ◽  
Internal Mixing ◽  
Respiratory Gases ◽  
Opening And Closing

Rhythmic patterns of compression and reinflation of the thin-walled hollow tubes of the insect tracheal system have been observed in a number of insects. These movements may be important for facilitating the transport and exchange of respiratory gases, but observing and characterizing the dynamics of internal physiological systems within live insects can be challenging due to their size and exoskeleton. Using synchrotron X-ray phase-contrast imaging, we observed dynamical behavior in the tracheal system of the beetle, Odontotaenius disjunctus. Similar to observations of tracheal compression in other insects, specific regions of tracheae in the thorax of O. disjunctus exhibit rhythmic collapse and reinflation. During tracheal compression, the opposing sides of a tracheal tube converge, causing the effective diameter of the tube to decrease. However, a unique characteristic of tracheal compression in this species is that certain tracheae collapse and reinflate with a wavelike motion. In the dorsal cephalic tracheae, compression begins anteriorly and continues until the tube is uniformly flattened; reinflation takes place in the reverse direction, starting with the posterior end of the tube and continuing until the tube is fully reinflated. We report the detailed kinematics of this pattern as well as additional observations that show tracheal compression coordinated with spiracle opening and closing. These findings suggest that tracheal compression may function to drive flow within the body, facilitating internal mixing of respiratory gases and ventilation of distal regions of the tracheal system.

Role of the sweating from the tail in the thermal balance of the rat-kangaroo Potorous tridactylus

1975 ◽  
Vol 23 (4) ◽  
pp. 453 ◽  
Author(s):  
JW Hudson ◽  
TJ Dawson
Keyword(s):  
Body Temperature ◽  
Heat Balance ◽  
Heat Load ◽  
Thermal Balance ◽  
The Body ◽  
Thermoregulatory Response ◽  
Thermoregulatory Responses ◽  
Air Temperatures ◽  
Potorous Tridactylus

Among the marsupials the thermoregulatory response of sweating is uncommon and has only been described in the larger macropodids. Sweating in kangaroos is very unusual in that it only occurs in response to an exercise heat load. The thermoregulatory responses of a smaller, more generalized rat-kangaroo Potorous tridactylus were therefore examined to obtain a more general appreciation of sweating in macropodids. The pattern of heat balance at low and neutral temperatures was characteristic of that previously found for macropodids; body temperature was 35.9 � 0.52 (mean � se). Standard metabolism was only slightly higher than the predicted level for marsupials and minimal conductance was low, c. 1.3 W m-2 per degree Celsius. At moderate air temperatures heat was primarily lost by vasodilation and panting. The thermoregulatory responses at high air temperatures (near or above body temperature) also included copious sweating from the tail, but not from the body generally. Sweating rates of 600-650 g water per m2 per hour were obtained; these are about twice the generally reported rates for eutherians such as cows and horses.

scholarly journals Role of preoptic opioid receptors in the body temperature reduction during hypoxia

2009 ◽  
Vol 1286 ◽  
pp. 66-74 ◽  
Author(s):  
Carolina da Silveira Scarpellini ◽  
Luciane H. Gargaglioni ◽  
Luis G.S. Branco ◽  
Kênia C. Bícego
Keyword(s):  
Body Temperature ◽  
Opioid Receptors ◽  
The Body ◽  
Temperature Reduction

scholarly journals Noncontact Body Temperature Measurement: Uncertainty Evaluation and Screening Decision Rule to Prevent the Spread of COVID-19

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 346
Author(s):  
Giovanni Battista Dell’Isola ◽  
Elena Cosentini ◽  
Laura Canale ◽  
Giorgio Ficco ◽  
Marco Dell’Isola
Keyword(s):  
Body Temperature ◽  
Temperature Measurement ◽  
Decision Rule ◽  
The Body ◽  
Threshold Temperature ◽  
Uncertainty Sources ◽  
Screening Protocol ◽  
Body Temperature Measurement ◽  
Measurement Uncertainty Evaluation

The need to measure body temperature contactless and quickly during the COVID-19 pandemic emergency has led to the widespread use of infrared thermometers, thermal imaging cameras and thermal scanners as an alternative to the traditional contact clinical thermometers. However, limits and issues of noncontact temperature measurement devices are not well known and technical–scientific literature itself sometimes provides conflicting reference values on the body and skin temperature of healthy subjects. To limit the risk of contagion, national authorities have set the obligation to measure body temperature of workers at the entrance to the workplace. In this paper, the authors analyze noncontact body temperature measurement issues from both clinical and metrological points of view with the aim to (i) improve body temperature measurements accuracy; (ii) estimate the uncertainty of body temperature measurement on the field; (iii) propose a screening decision rule for the prevention of the spread of COVID-19. The approach adopted in this paper takes into account both the traditional instrumental uncertainty sources and clinical–medical ones related to the subjectivity of the measurand. A proper screening protocol for body temperature measurement considering the role of uncertainty is essential to correctly choose the threshold temperature value and measurement method to access critical places during COVID-19 pandemic emergency.

scholarly journals Role of the Preoptic Area in Sleep and Thermoregulation

2021 ◽  
Vol 15 ◽  
Author(s):  
Rebecca Rothhaas ◽  
Shinjae Chung
Keyword(s):  
Body Temperature ◽  
Molecular Identification ◽  
Brain Region ◽  
Preoptic Area ◽  
The Body ◽  
Current Understanding ◽  
Falling Asleep ◽  
Health And Disease ◽  
Key Questions

Sleep and body temperature are tightly interconnected in mammals: warming up our body helps to fall asleep and the body temperature in turn drops while falling asleep. The preoptic area of the hypothalamus (POA) serves as an essential brain region to coordinate sleep and body temperature. Understanding how these two behaviors are controlled within the POA requires the molecular identification of the involved circuits and mapping their local and brain-wide connectivity. Here, we review our current understanding of how sleep and body temperature are regulated with a focus on recently discovered sleep- and thermo-regulatory POA neurons. We further discuss unresolved key questions including the anatomical and functional overlap of sleep- and thermo-regulatory neurons, their pathways and the role of various signaling molecules. We suggest that analysis of genetically defined circuits will provide novel insights into the mechanisms underlying the coordinated regulation of sleep and body temperature in health and disease.

scholarly journals The role of body temperature in regulating brain and body sizes in hominin evolution

2020 ◽  
Author(s):  
Manasvi Lingam
Keyword(s):  
Body Temperature ◽  
Quantitative Model ◽  
The Body ◽  
Foraging Efficiency ◽  
Fire Control ◽  
Hominin Evolution ◽  
Body Sizes ◽  
Feeding Activities ◽  
The Impact

AbstractA number of models have posited that the concomitant evolution of large brains and increased body sizes in hominins was constrained by metabolic costs. In such studies, the impact of body temperature has not been sufficiently addressed despite the well-established fact that the rates of most physiological processes are manifestly temperature-dependent. Hence, the role of body temperature in modulating the number of neurons and body size is investigated in this work by means of a simple quantitative model. It is determined that modest deviations in the body temperature (i.e., by a few degrees Celsius) might bring about substantive changes in brain and body parameters. In particular, a higher body temperature might prove amenable to an increase in the number of neurons, a higher brain-to-body mass ratio and fewer hours expended on feeding activities, while the converse applies when the temperature is lowered. It is therefore argued that future studies must endeavour to explore and incorporate the effects of body temperature in metabolic theories of hominin evolution, while also accounting for other factors such as foraging efficiency, diet and fire control in tandem.

Reduced febrile responses to pyrogens after lesions of the hypothalamic paraventricular nucleus

1994 ◽  
Vol 267 (1) ◽  
pp. R323-R328 ◽  
Author(s):  
T. Horn ◽  
M. F. Wilkinson ◽  
R. Landgraf ◽  
Q. J. Pittman
Keyword(s):  
Body Temperature ◽  
Paraventricular Nucleus ◽  
Radio Telemetry ◽  
The Body ◽  
Hypothalamic Paraventricular Nucleus ◽  
Febrile Response ◽  
Normal Body Temperature ◽  
Normal Body ◽  
Pg E2

The hypothalamic paraventricular nucleus (PVN) is recognized as a major site of autonomic control, but the role of this nucleus in thermoregulation is unclear. Therefore the role of the PVN in the febrile response and in the maintenance of normal body temperature was investigated. Conscious, unrestrained rats with chronic lesions of the PVN received intracerebroventricular injections of several doses of prostaglandin (PG) E2 or intraperitoneal applications of Escherichia coli lipopolysaccharide. The body temperatures of both lesioned and sham-operated animals, monitored via radio telemetry, were compared. Intracerebroventricular PGE2 at doses of 10, 25, and 50 ng caused dose-dependent fevers in both PVN-lesioned and sham-operated animals, which at lower doses were smaller in the lesioned animals than in the sham-operated animals. Intraperitoneal lipopolysaccharide application, 50 micrograms/kg body wt, evoked a significantly lower febrile response in PVN-lesioned animals than in controls. The body temperature of PVN-lesioned animals and controls showed no difference during 300 min of exposure to heat (32 degrees C) or cold (7 degrees C). These results suggest that the PVN contributes to the complex regulation of temperature during the febrile response but not during the maintenance of normal body temperature.

scholarly journals Role of body temperature variations in bat immune response to viral infections

2021 ◽  
Vol 18 (180) ◽  
pp. 20210211
Author(s):  
Maria Rita Fumagalli ◽  
Stefano Zapperi ◽  
Caterina A. M. La Porta
Keyword(s):  
Body Temperature ◽  
Viral Infections ◽  
Point Of View ◽  
The Body ◽  
Viral Escape ◽  
Temperature Cycle ◽  
Temperature Variations ◽  
Interesting Issue ◽  
Periodic Behaviour

The ability of bats to coexist with viruses without being harmed is an interesting issue that is still under investigation. Here we use a mathematical model to show that the pattern of body temperature variations observed in bats between day and night is responsible for their ability to keep viruses in check. From the dynamical systems point of view, our model displays an intriguing quasi-periodic behaviour that might be relevant in making the system robust by avoiding viral escape due to perturbations in the body temperature cycle.

Osmoregulation in Australian Freshwater Mussels (Lamellibranchiata). I. Water and Chloride Ion Exchange in Hyridella australis (Lam.)

1953 ◽  
Vol 4 (2) ◽  
pp. 317 ◽  
Author(s):  
ID Hiscock
Keyword(s):  
Water Exchange ◽  
External Medium ◽  
Chloride Ion ◽  
Pericardial Fluid ◽  
The Body ◽  
Equilibrium Level ◽  
The Difference ◽  
Effective Seal ◽  
Australian Freshwater

The chlorinities of the blood and pericardial fluid of H. australis are similar, but always exceed those of the normal external medium. A study of blood chloride changes in mussels in media of different concentrations has shown that immediately following a change of medium there is a change in blood chlorinity, which tends to assume a new equilibrium level within 24 hr. The rapidity with which this change occurs depends upon the difference between the chlorinity of the blood and that of the external medium. A study of water exchange under identical conditions has shown that significant changes occur in the hydration of the mussel. In hypotonic media the mussel can regulate its water content; in hypertonic media it cannot, but its hydration assumes a new level within 24 hr. It is concluded that some part of the body surface is permeable to both salts and water. The urine of the mussel is hypotonic to the blood; it remains remarkably stabre in chlorinity despite changes in blood chlorinity. The role of the kidney as a regulating organ is discussed. The significance of shell movements in osmoregulation is demonstrated. Shell closure has been shown to be an effective seal from the external medium, allowing the mussel to resist desiccation.

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