Human skin wettedness and evaporative efficiency of sweating

1979 ◽  
Vol 46 (3) ◽  
pp. 522-528 ◽  
Author(s):  
V. Candas ◽  
J. P. Libert ◽  
J. J. Vogt
Keyword(s):  
Sweat Rate ◽  
The Body ◽  
Body Temperatures ◽  
Skin Wettedness ◽  
Evaporative Heat Transfer ◽  
Evaporative Heat Transfer Coefficient ◽  
The Relationship ◽  
Male Subjects ◽  
Skin Temperatures ◽  
Different Levels

Rates of evaporation and sweating were recorded for three acclimatized male subjects in hot humid conditions, the ambient parameters of which were set so that the various imposed evaporative rates required the same skin wettedness at different levels of sweating. Rectal and skin temperatures were measured. Results showed that during steady state occurring during the 2nd h of exposure each subject reached the required evaporative rate by means of increases in skin wettedness regardless of the level of sweating; the sweat evaporative efficiency, defined as the ratio between evaporative rate and sweat rate, decreased as skin wettedness increased, in a range between 0.74 and 1.0 Sweat efficiency fell to 0.67 for fully wet skin. The body temperatures did not increase with time if skin wettedness was less than unity. Evaporative heat transfer coefficient (he), maximum evaporative capacity, and wettedness were estimated on the basis of the observed decrease of sweat efficiency. The relationship between skin wettedness and sweat efficiency was interpreted as a combined effect of differences in local he as well as in local sweat rates.

Effects of modafinil on heat thermoregulatory responses in humans at rest

2002 ◽  
Vol 80 (8) ◽  
pp. 796-803 ◽  
Author(s):  
Jean-Claude Launay ◽  
Yves Besnard ◽  
Angélique Guinet ◽  
Germain Bessard ◽  
Christian Raphel ◽  
...  
Keyword(s):  
Heat Storage ◽  
Sweat Rate ◽  
Heat Exposure ◽  
Body Temperatures ◽  
Metabolic Heat ◽  
Thermoregulatory Responses ◽  
The Central Nervous System ◽  
Male Subjects ◽  
Skin Temperatures ◽  
Body Heat

The effects of modafinil on heat thermoregulatory responses were studied in 10 male subjects submitted to a sweating test after taking 200 mg of modafinil or placebo. Sweating tests were performed in a hot climatic chamber (45°C, relative humidity <15%, wind speed = 0.8 m·s–1, duration 1.5 h). Body temperatures (rectal (Tre) and 10 skin temperatures (Tsk)), sweat rate, and metabolic heat production (Mdot) were studied as well as heart rate (HR). Results showed that modafinil induced at the end of the sweating test higher body temperatures increases (0.50 ± 0.04 versus 0.24 ± 0.05°C (P < 0.01) for deltaTre and 3.64 ± 0.16 versus 3.32 ± 0.16°C (P < 0.05) for deltaTbarsk (mean skin temperature)) and a decrease in sweating rate throughout the heat exposure (P < 0.05) without change in Mdot, leading to a higher body heat storage (P < 0.05). DeltaHR was also increased, especially at the end of the sweating test (17.95 ± 1.49 versus 12.52 ± 1.24 beats/min (P < 0.01)). In conclusion, modafinil induced a slight hyperthermic effect during passive dry heat exposure related to a lower sweat rate, probably by its action on the central nervous system, and this could impair heat tolerance. Key words: modafinil, heat, human, thermoregulation.

Sweating and body temperatures following abrupt changes in environmental temperature

1962 ◽  
Vol 17 (1) ◽  
pp. 103-106 ◽  
Author(s):  
H. S. Belding ◽  
B. A. Hertig
Keyword(s):  
Skin Temperature ◽  
Environmental Temperature ◽  
Sweat Rate ◽  
Human Subjects ◽  
Body Temperatures ◽  
Hypothalamic Temperature ◽  
Abrupt Changes ◽  
Consistent Change ◽  
Different Levels ◽  
Skin Receptors

Human subjects were transferred between environments imposing different levels of heat stress. Analyses of measurements obtained after a reasonably steady state had been achieved in each of several environments revealed equally good correlation between a) sweat rate and ear temperature (tympanic membrane), and b) sweat rate and calculated deep skin temperature (hypothetical). The correlations are consistent with adjustment of sweating in response to either hypothalamic temperature or temperature of skin receptors or some combination of the two. However, during the first 20 min after transfer, changes in sweat rate and skin temperature occurred together and in the same direction, but were not accompanied by any consistent change in ear temperature. Thus, to the extent that ear temperature represents hypothalamic temperature, an hypothesis of control of sweating based on hypothalamic temperature alone is not tenable. Alternative physiological explanations are given for data developed elsewhere and used in support of an hypothesis of sweat control solely from the hypothalamus. Submitted on August 14, 1961

scholarly journals TMJ Dysfunction and Systemic Correlation

2020 ◽  
Vol 5 (1) ◽  
pp. 20 ◽  
Author(s):  
Luca Fiorillo ◽  
Giuseppe Musumeci
Keyword(s):  
The Body ◽  
Mixed Dentition ◽  
Dental Occlusion ◽  
Sports Performance ◽  
Muscular System ◽  
Medical Field ◽  
Starting Point ◽  
A Site ◽  
The Relationship ◽  
Different Levels

In recent years it has been conclusively shown how the position of the mouth in relation to the body affects the way of walking and standing. In particular, occlusion, the relationship between skull and jaw, swallowing and convergence of the eyes are in neuro-muscular relationship with the control and maintenance system of posture, integrating at different levels. This manuscript aims to be a summary of all the oral, occlusal and articular dysfunctions of TMJ with systemic and postural–muscular repercussions. Recent articles found in the literature that are taken into consideration and briefly analyzed represent an important starting point for these correlations, which are still unclear in the medical field. Posturology, occlusal and oral influences on posture, spine and muscular system are still much debated today. In the literature, there are articles concerning sports performance and dental occlusion or even the postural characteristics of adolescents or children in deciduous and mixed dentition. The temporomandibular joint, as the only joint of the skull, could therefore represent a site to pay particular attention to, and in some cases an ATM dysfunction could be a clue for the diagnosis of systemic pathologies, or it could be the repercussion.

Changing physiological relationships in men under acute cold stress

1970 ◽  
Vol 48 (1) ◽  
pp. 1-10 ◽  
Author(s):  
James F. O'Hanlon Jr. ◽  
Steven M. Horvath
Keyword(s):  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Heat Content ◽  
Body Temperatures ◽  
Older Subjects ◽  
Skin Temperatures ◽  
Different Levels ◽  
Body Heat ◽  
Thigh Temperature

Thirty-four men were exposed to 8 °C for 2 h. Their reactions were studied to indicate how physiological relationships change during exposure to cold. Measurements of various body temperatures, MST, MBT, body heat content (BHC), [Formula: see text], heat production, and heart rate (HR) were made before the onset of and periodically during cold exposure. Various skin temperatures fell to different levels while rectal temperature rose slightly, then fell 0.3 °C by the end of the exposure. BHC declined by 6%, [Formula: see text] nearly doubled, [Formula: see text] and heat production increased by 66 and 75% respectively, and HR changed little during cold exposure. Relationships which changed most significantly during cold exposure were those between MST and rectal temperature, certain skin temperatures and rectal temperature, [Formula: see text] (also heat production) and BHC, [Formula: see text] and rectal temperature, and finally, those between every body temperature and the age of the subjects. Relationships which also changed were those between finger and toe temperature as well as those between [Formula: see text] (also heat production) and each of the following: [Formula: see text], rectal temperature, thigh temperature, HR, and age. These results indicated that (1) temperature in the upper extremities was actively maintained at a higher level than temperature in the lower extremities, (2) increased metabolism became a progressively more effective adaptation than redistribution of blood volume, (3) subjects with the lowest BHC tended to increase their metabolism the most, (4) [Formula: see text] was inversely related to core temperature after the latter fell below normal, (5) HR was unrelated to the increase in [Formula: see text], (6) the usual inverse relationship between age and metabolism was not found in the cold, and finally, (7) older subjects generally tended to maintain higher body temperatures than younger subjects.

scholarly journals Thermal biology of Amphisbaena munoai (Squamata: Amphisbaenidae)

2018 ◽  
Vol 35 ◽  
pp. 1-9 ◽  
Author(s):  
Nathalia Rocha Matias ◽  
Laura Verrastro
Keyword(s):  
Body Temperature ◽  
Ambient Temperature ◽  
Thermal Environment ◽  
Rio Grande ◽  
The Body ◽  
Rio Grande Do Sul ◽  
Body Temperatures ◽  
Physiological Mechanisms ◽  
Thermal Biology ◽  
The Relationship

Studies on the thermal biology of fossorial reptiles that examine the relationship between the body temperature and thermal environment are needed to determine the extent of their thermoregulation abilities. This study assessed the thermal biology of Amphisbaena munoai Klappenbach, 1969 in the rocky fields of the Rio Grande do Sul and in the laboratory. The body temperature of most individuals was between 24 and 30 °C, both in the field (n = 81) and laboratory (n = 19). More individuals were caught in winter (n = 55) and spring (n = 60) than in summer (n = 25) and fall (n = 45), and in spring, individuals showed similar nocturnal and diurnal activities. In the laboratory, we found individuals with body temperatures up to 5 °C higher than the ambient temperature (n = 4), suggesting that some physiological mechanisms participate in the thermoregulation of these animals. Amphisbaena munoai is a thigmothermic species that is capable of actively regulating its temperature by selecting microhabitats such that its various activities occur within an ideal temperature range. This study is the first to evaluate the effect of seasonality and diurnal and nocturnal variations on the thermoregulation of an amphisbaenid.

Some aspects of body temperature regulation in sheep

1968 ◽  
Vol 71 (1) ◽  
pp. 61-66 ◽  
Author(s):  
M. E. D. Webster ◽  
K. G. Johnson
Keyword(s):  
Body Temperature ◽  
Surface Area ◽  
Cold Water ◽  
The Body ◽  
Body Temperatures ◽  
Mean Body Temperature ◽  
Merino Sheep ◽  
Infra Red ◽  
Heat Increment ◽  
Skin Temperatures

SummarySkin temperatures, deep body temperatures and respiratory rates have been measured in Southdown and Merino sheep following feeding, and during infra-red irradiation, rumen infusions of hot and cold water, and cold exposure induced by shearing. The increases in respiratory rate and skin temperatures induced by infra-red heating and the heat increment of feeding were reversed by addition of iced water to the rumen and were suppressed by shearing. These responses could not be systematically related to particular body temperatures in the sheep and appeared to be continuously variable rather than ‘all-or-none’ phenomena. Considerable overlap was observed between respiratory and vasomotor mechanisms of thermoregulation. Measurements of the surface area and weight of ears and legs showed that these regions contribute approximately 23% of the surface area and 8% of the body weight in Merino sheep. Calculations suggested that up to 70% of the additional heat produced in the 2 h after feeding in sheep may be stored in the tissues through increase in mean body temperature. Sheep kept in short wool throughout the winter appeared to establish a new thermoregulatory ‘set-point’ associated with lower rectal temperatures than those in sheep with a full fleece.

Physical performance and peak aerobic power at different body temperatures

1979 ◽  
Vol 46 (5) ◽  
pp. 885-889 ◽  
Author(s):  
U. Bergh ◽  
B. Ekblom
Keyword(s):  
Physical Performance ◽  
Aerobic Power ◽  
Pulmonary Ventilation ◽  
Time To Exhaustion ◽  
Body Temperatures ◽  
Performance Time ◽  
Peak Vo2 ◽  
Leg Exercise ◽  
Male Subjects ◽  
Skin Temperatures

In eight male subjects we studied the effect of different core (esophageal, (Tes 34.9--38.4 degrees C) and muscle (Tm 35.1--39.3 degrees C) temperature on 1) physical performance (time to exhaustion at a standard maximal rate of work, WT), 2) aerobic power (VO2), 3) heart rate (HR), and 4) blood lactate (LA) concentration during exhaustive combined arm and leg exercise. In three subjects the effects at different mean skin temperatures (Tsk 27 and 31 degrees C, respectively) were also studied. Peak VO2 was positively correlated to both Tes (r = 0.88) and Tm (r = 0.91). None of the subjects attained control VO2max at Tes and Tm lower than 37.5 and 38.0 degrees C, respectively. HR was correlated to both Tes (r = 0.97) and Tm (r = 0.95). Different Tsk did not affect peak VO2 and HR at subnormal body temperatures. Pulmonary ventilation was independent of Tes and Tm in all experimental situations. LA was significantly higher at Tes 37.5 degrees C compared to both Tes 34.9 and 38.5 degrees C, respectively. At Tes less than 37.5 degrees C and Tm less than 38.0 degrees C, there was a linear reduction in WT (20%.degrees C-1), peak VO2 (5--6%.degrees C-1), and HR (8 beats.min-1.degrees C-1) with lowered Tes and Tm.

Calculation of mean body temperature

1968 ◽  
Vol 46 (1) ◽  
pp. 15-17 ◽  
Author(s):  
S. D. Livingstone
Keyword(s):  
Skin Temperature ◽  
Initial Period ◽  
Young Male ◽  
Heat Losses ◽  
The Body ◽  
Body Temperatures ◽  
Mean Body Temperature ◽  
Constant Coefficients ◽  
Environmental Temperatures ◽  
Male Subjects

Four young male subjects were exposed for 1 h to environmental temperatures of 8.5 °C, 14.0 °C, and 20.0 °C while lying on a rope mesh cot. During exposure they wore swimming trunks only. Heat production, skin temperature at seven locations, and rectal temperature were measured. Mean body temperatures (MBT) and heat debts were calculated from Burton's equations and also from equations determining radiative, convective, and evaporative heat losses. It was found that a linear equation with constant coefficients, such as Burton's, for measuring MBT does not allow for the fact that in the non-steady state the body continues to lose heat even though the skin temperature is relatively constant. During the initial period of cold exposure the coefficient of skin temperature when calculating MBT should be much smaller than at later stages in the cooling.

Physiological index of strain and body heat storage in hyperthermia

1960 ◽  
Vol 15 (6) ◽  
pp. 1027-1030 ◽  
Author(s):  
John F. Hall ◽  
J. W. Polte
Keyword(s):  
Heat Storage ◽  
Sweat Rate ◽  
Individual Variability ◽  
Physiological Strain ◽  
Strain Index ◽  
Stress Levels ◽  
Group Variation ◽  
The Relationship ◽  
Male Subjects ◽  
Body Heat

Individual variability of a modified Craig index of physiological strain and body heat storage was determined, and the relationship between these parameters defined for five healthy, nonacclimatized male subjects exposed five times to each of three heat stress levels: 38°C, 54°C and 71°C at a vapor pressure of 10 mm Hg. This index contains the variables of heart rate, sweat rate and rate of rectal temperature change, measured by EKG, nude pre- and post-experimental weighings, and a rectal thermistor, respectively. Body heat storage was calculated from initial and terminal weighted mean skin and rectal temperatures. Subjects were sitting and wore 1 clo of body insulation. Individual and group variation for strain index and body heat storage was determined. The data show a linear relationship between these expressions over the thermal stress range investigated although individual variability was considerable at the higher stress levels. A statistically significant correlation between strain index and body heat storage is shown. Submitted on May 16, 1960

Effects of carbon dioxide inhalation on sweating

1964 ◽  
Vol 19 (1) ◽  
pp. 137-141 ◽  
Author(s):  
Robert W. Bullard
Keyword(s):  
Carbon Dioxide ◽  
Body Temperature ◽  
Tympanic Membrane ◽  
Sweat Gland ◽  
Recovery Period ◽  
Body Temperatures ◽  
Ambient Temperatures ◽  
Effector Activity ◽  
Male Subjects ◽  
Skin Temperatures

Inhalation of 6% carbon dioxide by male subjects exposed to three different ambient temperatures resulted in increased sweating as measured by resistance hygrometry. The increase, which occurred in all body areas studied, reached approximately 100% over the control levels. All measured body temperatures decreased during or immediately following the carbon dioxide period. In the recovery period a marked depression of sweating occurred which ended as skin temperatures increased. body temperature; thermal effector activity (cyclic sweat gland activity); skin temperature; tympanic membrane and hypothalamus temperatures; resistance hygrometry responses to heat Submitted on April 24, 1963

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