A mechanism by which helium increases metabolism in small mammals

1960 ◽  
Vol 199 (2) ◽  
pp. 243-245 ◽  
Author(s):  
H. A. Leon ◽  
S. F. Cook
Keyword(s):  
Thermal Conductivity ◽  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Skin Temperature ◽  
Heat Loss ◽  
Small Mammals ◽  
Thermal Gradient ◽  
Oxygen Mixture ◽  
Ambient Temperatures ◽  
Long Evans

The oxygen consumption of male Long-Evans rats was determined at three different ambient temperatures in air and in an equivalent helium-oxygen mixture. It was found that when the ambient temperature is near the skin temperature of the rat, the effect of helium is insignificant. If the ambient temperature is lowered, helium induces an increased metabolism over air at the same temperature. Since helium has a thermal conductivity about six times greater than nitrogen, it is concluded that the accelerated metabolism is in response to the greater heat loss in the presence of helium and the magnitude of this response is proportional to the thermal gradient between the animal and the environment.

Energy savings from vocal regulation of ambient temperature by 3-day-old domestic chicks

1996 ◽  
Vol 74 (4) ◽  
pp. 599-605 ◽  
Author(s):  
Anton Espira ◽  
Roger M. Evans
Keyword(s):  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Thermal Gradient ◽  
Energy Savings ◽  
Net Energy ◽  
Natural Conditions ◽  
Ambient Temperatures ◽  
Domestic Chicks ◽  
Important Means ◽  
Cold Challenge

Precocial domestic chicks (Gallus domesticus) become endothermic at or soon after hatching, but when chilled still vocalize to solicit heat from a parent or surrogate. In this study, we examined the potential energy savings resulting from vocal solicitation of heat by comparing the oxygen consumption of 3-day-old chicks facing a cold challenge of 20 °C with and without the option of regulating ambient temperature by vocally soliciting 2-min periods of rewarming at 35 °C from a surrogate parent in the laboratory. Body temperature was unaffected by vocal regulation, but the thermal gradient between body and ambient temperature was reduced by 5.0 ± 0.4 °C (mean ± SE). Mass-specific oxygen consumption [Formula: see text] increased by 62.5% to a near steady state mean of 3.64 mL∙g−1∙h−1 during constant chilling at 20 °C, but increased by only 48.1%, to 3.08 mL∙g−1∙h−1, during vocal regulation. Relative to chilled controls, vocally regulating chicks had a mean net energy saving of 15.4% during the final, stable 15 min of testing. Vocal solicitation of heat from a brooding parent seems likely to be an important means of saving energy expended in thermoregulation in some precocial species when young chicks are exposed to low ambient temperatures under natural conditions.

Thermoregulation of African and European Honeybees during Foraging, Attack, and Hive Exits and Returns

1979 ◽  
Vol 80 (1) ◽  
pp. 217-229 ◽  
Author(s):  
HEINRICH BERND
Keyword(s):  
Metabolic Rate ◽  
Ambient Temperature ◽  
Heat Loss ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thoracic Temperature

1. While foraging, attacking, or leaving or returning to their hives, both the African and European honeybees maintained their thoracic temperature at 30 °C or above, independent of ambient temperature from 7 to 23 °C (in shade). 2. Thoracic temperatures were not significantly different between African and European bees. 3. Thoracic temperatures were significantly different during different activities. Average thoracic temperatures (at ambient temperatures of 8–23 °C) were lowest (30 °C) in bees turning to the hive. They were 31–32 °C during foraging, and 36–38 °C in bees leaving the hive, and in those attacking. The bees thus warm up above their temperature in the hive (32 °C) before leaving the colony. 4. In the laboratory the bees (European) did not maintain the minimum thoracic temperature for continuous flight (27 °C) at 10 °C. When forced to remain in continuous flight for at least 2 min, thoracic temperature averaged 15 °C above ambient temperature from 15 to 25 °C, and was regulated only at high ambient temperatures (30–40 °C). 5. At ambient temperatures > 25 °C, the bees heated up during return to the hive, attack and foraging above the thoracic temperatures they regulated at low ambient temperatures to near the temperatures they regulated during continuous flight. 6. In both African and European bees, attack behaviour and high thoracic temperature are correlated. 7. The data suggest that the bees regulate thoracic temperature by both behavioural and physiological means. It can be inferred that the African bees have a higher metabolic rate than the European, but their smaller size, which facilitates more rapid heat loss, results in similar thoracic temperatures.

The metabolic rates of newborn pigs in relation to floor insulation and ambient temperature

1971 ◽  
Vol 13 (2) ◽  
pp. 303-313 ◽  
Author(s):  
D. B. Stephens
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Regression Coefficients ◽  
Metabolic Rates ◽  
Similar Treatment ◽  
Concrete Floor ◽  
Ambient Temperatures ◽  
Newborn Pigs ◽  
Floor Material

SUMMARY1. The metabolic rates of 58 individual piglets kept either on a straw or on a concrete floor at ambient temperatures near to 10°, 20° or 30°C have been measured with ages ranging from newborn to 9 days, and body weight from 1·0 to 3·2 kg. The oxygen consumption was measured on each floor material at the chosen ambient temperature thus allowing paired comparisons for each animal.2. In comparison with the concrete floor, oxygen consumption on straw was reduced by 18% at 10°C, 27% at 20°C and by 12% at 30°C for pigs 2 to 9 days old. The regression coefficients of mean log (oxygen consumption) on log (body weight) were around 0·66 at 10° and 20°C. At 30°C the value was 0·99 ± 0·14. The regression coefficients were not significantly affected by the presence of a straw floor showing that its effect did not vary with body weight. Corresponding values foi piglets below 24 hours of age were 17% at 10°C, 27% at 20°C and 22% at 30°C ambient temperature.3. Moving a piglet on to a straw floor at 10°C had the same thermal effect as raising the ambient temperature to 18°C. Similar treatment at 30°C was equivalent to raising the ambient temperature to 32°C.4. Lowering ambient temperature to increase the temperature gradient between the homeothermic body of the piglet and the environment progressively increased heat loss in all cases. There was a concomitant decrease in the calculated conductance between core and environment which was more pronounced for the piglets lying on the concrete floor.

Temperature regulation and cold acclimation in the golden hamster

1965 ◽  
Vol 20 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Hermann Pohl
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Ambient Temperature ◽  
Cold Acclimation ◽  
Heat Production ◽  
Golden Hamster ◽  
Thermal Conductance ◽  
Muscular Activity ◽  
The Body ◽  
Ambient Temperatures

Characteristics of cold acclimation in the golden hamster, Mesocricetus auratus, were 1) higher metabolic rate at -30 C, 2) less shivering when related to ambient temperature or oxygen consumption, and 3) higher differences in body temperature between cardiac area and thoracic subcutaneous tissues at all ambient temperatures tested, indicating changes in tissue insulation. Cold-acclimated hamsters also showed a rise in temperature of the cardiac area when ambient temperature was below 15 C. Changes in heat distribution in cold-acclimated hamsters suggest higher blood flow and heat production in the thoracic part of the body in the cold. The thermal conductance through the thoracic and lumbar muscle areas, however, did not change notably with lowering ambient temperature. Marked differences in thermoregulatory response to cold after cold acclimation were found between two species, the golden hamster and the thirteen-lined ground squirrel, showing greater ability to regulate body temperature in the cold in hamsters. hibernator; oxygen consumption— heat production; body temperature — heat conductance; muscular activity — shivering; thermoregulation Submitted on July 6, 1964

Thermal comfort in relation to mean skin temperature

1970 ◽  
Vol 48 (2) ◽  
pp. 98-101 ◽  
Author(s):  
E. D. L. Topliff ◽  
S. D. Livingstone
Keyword(s):  
Thermal Comfort ◽  
Ambient Temperature ◽  
Skin Temperature ◽  
Incident Radiation ◽  
Mean Skin Temperature ◽  
Ambient Temperatures ◽  
The Mean ◽  
Per Se

Nude men were exposed to a range of ambient temperatures and were brought to a condition of thermal comfort by adjustment of the incident radiation. The mean skin temperature associated with comfort was found to be different for each combination of ambient temperature and incident radiation. It was evident that mean skin temperature, per se, was not a dependable criterion of thermal comfort.

Hand-Skin Temperature and Dexterity

1979 ◽  
Vol 23 (1) ◽  
pp. 183-187
Author(s):  
Michael W. Riley ◽  
Denise M. Allison
Keyword(s):  
Ambient Temperature ◽  
Skin Temperature ◽  
Research Study ◽  
Measurement Methods ◽  
Industrial Worker ◽  
Male And Female ◽  
Assembly Task ◽  
Ambient Temperatures ◽  
Better Than ◽  
Female Subjects

This research study examined the dexterity performance of both male and female subjects at ambient temperatures of 35°, 55° and 75°F. Subjects wore typical industrial worker apparel without gloves. Four dexterity measurement methods were used. These were 1) Purdue Pegboard, 2) pencil point tapping, 3) an assembly task, and 4) a fine manipulative task. The subject's performance scores at the various tasks were correlated with the ambient temperature and the hand-skin temperature. Results indicate that females scored better than males on the Purdue Pegboard and a fine manipulative task at all temperatures, while males scored better in pencil point tapping and an assembly task.

Shorn and unshorn Awassi sheep IV. Skin temperature and changes in temperature and humidity in the fleece and its surface

1963 ◽  
Vol 60 (2) ◽  
pp. 183-193 ◽  
Author(s):  
E. Eyal
Keyword(s):  
Ambient Temperature ◽  
Skin Temperature ◽  
Vapour Pressure ◽  
The Sun ◽  
Direct Sunlight ◽  
Ambient Temperatures ◽  
Awassi Sheep ◽  
Break Points ◽  
Environmental Temperatures ◽  
Skin Temperatures

1. A comparison was made between the skin temperature, humidity and temperature within and on the surface of the fleece of unshorn and shorn sheep. This study was conducted during various seasons of the year, at different environmental temperatures, while sheep were maintained in the shade or subjected to direct sunlight.2. Accompanying the rise of ambient temperature (in the shade) from 10 to 43° C. there was an increase in skin temperature from 34 to 40° C. and from 28 to 40° C. of the unshorn and shorn sheep, respectively.3. The relationship between the rise in skin temperature and that of ambient temperature was not linear, but showed a stepwise pattern in which the ‘breaks’ occurred at similar environmental temperatures for both groups, although skin temperatures of shorn sheep were lower than the unshorn.4. The diurnal change in skin temperature of the shorn sheep was similar to that of the ambient temperature. The decrease in skin temperature of unshorn sheep sometimes lagged behind the fall in environmental temperature. The seasonal variations between summer and winter were more significant in shorn than in unshorn sheep.5. Fleece surface temperatures measured at the same ambient temperatures ranged between 13 and42° C. and 16·5–39·5° C. in the unshorn and shorn sheep, respectively. In the break points of the rise in skin temperature, there occurred a drop in temperature gradients between the skin and fleece surface. This probably indicates a rise in thermal conductivity of the fleece at these points.6. The temperature gradient per unit of fleece thickness is inversely related to the depth of fleece and is greater the nearer to the skin.7. With exposure to the sun, skin temperatures of both groups greatly increased and occasionally reached 47° C. Under these conditions the differences between shorn and unshorn groups were not consistent.8. Fleece temperatures of unshorn sheep increased greatly upon exposure to the sun. The maximal temperatures were recorded midway between the fleece surface and skin. These temperatures generally reached 55° C. and sometimes even exceeded 60° C.9. At ambient temperatures of 30–35° C. the vapour pressure close to the skin of unshorn sheep ranged between 35–40 mm. Hg. With shorn sheep, however, the vapour pressure close to the skin was similar to that of the environment. In Yotvata there was a rise in vapour pressure close to the skin when the ambient temperature increased to 40–43° C. This rise in humidity was paralleled by a rise of vapour pressure throughout the wool. It was not linear but rather showed a ‘step-wise’ pattern.10. The vapour pressure in fleece and near the skin of sheep subjected to direct sunlight increased considerably (up to 80 mm. Hg). This rise showed a wave-like curve with various degrees of persistency. Appearance of fluid on the skin of Awassi sheep was observed on several occasions.

scholarly journals A revised method to predict skin’s thermal resistance

2018 ◽  
Vol 22 (4) ◽  
pp. 1795-1802
Author(s):  
Lijuan Wang ◽  
Ding Chong ◽  
Yuhui Di ◽  
Hui Yi
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Low Temperature ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Skin Temperature ◽  
Heat Loss ◽  
Human Body ◽  
New Formula ◽  
Sweat Evaporation

Human body can adjust heat loss by vasoconstriction, vasodilatation, and other methods. The purpose of this research is to investigate whether the thermal resistance of skin reflects vasoconstriction and vasodilatation. For this aim, the ambient temperature was controlled as 18.1, 21.6, 24.9, 27, and 30.5?C, respectively. In each temperature, the skin temperature and heat flux in the forearm were recorded. Based on tested data, the thermal resistance was calculated by a common method. The results showed that the thermal resistance at low temperature was less than that at high temperature, which was contrary to the rule of vasoconstriction and vasodilatation. So a new formula for thermal resistance was presented based on skin diffusion, sweat evaporation, and mass transformation. The results showed that the new method could predict vasoconstriction and vasodilatation. The revised equation is a useful index for physiological thermoregulation.

scholarly journals ENDOTHERMY IN THE SOLITARY BEE ANTHOPHORA PLUMIPES: INDEPENDENT MEASURES OF THERMOREGULATORY ABILITY, COSTS OF WARM-UP AND THE ROLE OF BODY SIZE

1993 ◽  
Vol 174 (1) ◽  
pp. 299-320 ◽  
Author(s):  
G. N. Stone
Keyword(s):  
Ambient Temperature ◽  
Heat Loss ◽  
Body Mass ◽  
Thermal Power ◽  
Thermal Conditions ◽  
Energetic Cost ◽  
Solitary Bee ◽  
Warm Up ◽  
Ambient Temperatures ◽  
Thoracic Temperature

1. This study examines variation in thoracic temperatures, rates of pre-flight warm-up and heat loss in the solitary bee Anthophora plumipes (Hymenoptera; Anthophoridae). 2. Thoracic temperatures were measured both during free flight in the field and during tethered flight in the laboratory, over a range of ambient temperatures. These two techniques give independent measures of thermoregulatory ability. In terms of the gradient of thoracic temperature on ambient temperature, thermoregulation by A. plumipes is more effective before flight than during flight. 3. Warm-up rates and body temperatures correlate positively with body mass, while mass-specific rates of heat loss correlate negatively with body mass. Larger bees are significantly more likely to achieve flight temperatures at low ambient temperatures. 4. Simultaneous measurement of thoracic and abdominal temperatures shows that A. plumipes is capable of regulating heat flow between thorax and abdomen. Accelerated thoracic cooling is only demonstrated at high ambient temperatures. 5. Anthophora plumipes is able to fly at low ambient temperatures by tolerating thoracic temperatures as low as 25 sC, reducing the metabolic expense of endothermic activity. 6. Rates of heat generation and loss are used to calculate the thermal power generated by A. plumipes and the total energetic cost of warm-up under different thermal conditions. The power generated increases with thoracic temperature excess and ambient temperature. The total cost of warm-up correlates negatively with ambient temperature.

TEMPERATURE REGULATION IN PREMATURE INFANTS

PEDIATRICS ◽  
1964 ◽  
Vol 33 (4) ◽  
pp. 487-495
Author(s):  
Forrest H. Adams ◽  
Tetsuro Fujiwara ◽  
Robert Spears ◽  
Joan Hodgman
Keyword(s):  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Respiratory Rate ◽  
Premature Infants ◽  
Rectal Temperature ◽  
Age Groups ◽  
Carbon Dioxide Production ◽  
High Ambient Temperature ◽  
Ambient Temperatures ◽  
The Mean

Sixteen serial observations of oxygen consumption, carbon dioxide production, R.Q., respiratory rate, rectal temperature, and skin blood flow were made on six premature infants ranging in age from 3 hours to 12 days and weighing from 1.14 to 1.94 kg, utilizing a specially designed climatized chamber at neutral (32-34°C), low (21-23°C), and high (36-38°C) ambient temperatures. Ten premature infants ranging in age from 2½ hours to 18 days were studied at high (36-38°C) ambient temperature. At low ambient temperature, there was a mean increase of 63% in oxygen consumption even in infants under 24 hours of age. At the end of the rewarming period, rectal temperature, which had been lowered during a 20-minute exposure to 21-23°C, nearly recovered to the original level in infants in both of the age groups of 0 to 24 hours and 2 to 5 days, whereas in the 6 to 12 day old group, it returned faster than the former two and it was increased by 0.32 to 1.9°C (mean 0.9°C). At 36-38°C, ambient temperature, the mean oxygen consumption increased 18% in infants ages 2½ to 7½ hours, whereas there was no significant increase in infants ages 10 to 18 days. Sweating and significant vasodilatation generally did not occur even in the older infants. The respiratory rate was increased in most infants. It is suggested that heat loss through the respiratory tract might be important to the premature infant who has a lack of evaporative means at high ambient temperature.

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