Role of skin and of core temperatures in man's temperature regulation

1965 ◽  
Vol 20 (1) ◽  
pp. 31-36 ◽  
Author(s):  
C. H. Wyndham
Keyword(s):  
Skin Temperature ◽  
Rectal Temperature ◽  
Temperature Regulation ◽  
Passive Control ◽  
Sweat Rate ◽  
Heat Conductance ◽  
Response Characteristics ◽  
Highly Nonlinear ◽  
The Right ◽  
Skin Temperatures

The response characteristics have been studied of the curves relating heat conductance and sweat rate to change in rectal temperature at different levels of skin temperature, and vice versa. The increase in these responses with deviation in rectal temperature from the “neutral” setting is highly nonlinear; the neutral point and the curve shift to the right and the slope decreases with lowering of skin temperature and vice versa when it is raised. With further deviation of rectal temperature these responses reach maximum values, i.e., become “saturated.” All of these features are analogous to servomechanisms with negative feedback, giving sensitive and stable control. Control of these responses by skin temperature is more linear, characterizing passive control systems which are insensitive and less stable. Quantitatively, the effect at skin temperature of 26 C of 1 C rise in rectal temperature on heat conductance and sweat rate is 10 times greater than the same rise in skin temperature; at a neutral skin temperature of 33–34 C, a rise of 1 C in rectal temperature is 6–7 times greater; at a high skin temperature of 36 C, a rise in rectal temperature of 1 C is 4–5 times greater. relationship between heat conductance and a change in either rectal or skin temperatures; relationship between sweat rate and a change in either rectal or skin temperatures; response characteristics of curves relating heat conductance to change in either rectal or skin temperatures; response characteristics of curves relating sweat rate to change in either rectal or skin temperatures; assessment of the contribution of skin and rectal temperatures to man's temperature regulation Submitted on October 22, 1963

Effects of sodium salicylate on physiological responses to work in heat

1964 ◽  
Vol 19 (1) ◽  
pp. 33-36 ◽  
Author(s):  
Eugene D. Jacobson ◽  
David E. Bass
Keyword(s):  
Skin Temperature ◽  
Pulse Rate ◽  
Rectal Temperature ◽  
Temperature Regulation ◽  
Sodium Salicylate ◽  
Sweat Rate ◽  
High Dose ◽  
Desert Environment ◽  
Ambient Conditions ◽  
Hot Environments

The hypothesis was tested that men given sodium salicylate would work in the heat at a lower level of temperature regulation. Healthy young volunteers were exposed to a standardized workload consisting of a 100-min walk at 3.5 mph on a level treadmill. Two ambient conditions were studied: a) simulated desert (120 F D.B., 80 F W.B.) and b) simulated jungle (92 F D.B., 87 F W.B.). Rectal temperature (Tr), skin temperature (Ts), sweat rate ( SR), and pulse rate ( PR) were measured in the subjects during work in the heat under three drug regimens: no drug (control), 0.6 g (low dose), and 7.8 g (high dose). It was found that sodium salicylate had no effect on Ts or PR compared with control; this finding applied to both doses in both hot environments. There was, however, a higher Tr and SR in men who received the high dose of the drug in the tropic environment and an increased SR in the desert climate. There was no decrease in Tr in the desert environment during salicylate administration. The results of this investigation do not confirm the original hypothesis; to the contrary, they suggest that high doses of sodium salicylate potentiates the hyperthermia of unacclimatized men working in the heat. body temperature regulation; exercise; simulated desert environment; simulated jungle environment; hyperthermia; rectal temperature, skin temperature, sweat rate, and pulse rate in hot environments; antipyretics Submitted on August 26, 1963

Criteria for physiological limits for work in heat

1965 ◽  
Vol 20 (1) ◽  
pp. 37-45 ◽  
Author(s):  
C. H. Wyndham ◽  
N. B. Strydom ◽  
J. F. Morrison ◽  
C. G. Williams ◽  
G. A. G. Bredell ◽  
...  
Keyword(s):  
Rectal Temperature ◽  
Temperature Regulation ◽  
Sweat Rate ◽  
Human Sciences ◽  
Laboratory Studies ◽  
Physiological Strain ◽  
Saturated Control ◽  
Physiological Limits ◽  
Upper Limit

New physiological criteria are put forward for setting the limits for men at work in hot conditions. They are based upon the fact that the curves relating rectal temperatures to conductances and rectal temperatures to sweat rates have two components. One is where the increases in the sweat rates and conductances, with rise in rectal temperature, are relatively large, i.e., there is a “sensitive” range of control; the second is where the curves of sweat rates and conductances against rectal temperatures reach asymptotes, i.e., become “saturated.” The upper limit of the sensitive range is a rectal temperature of 100.5 F (38.1 C), and the saturated range begins at rectal temperatures of 102.5 F (39.4 C). These concepts explain the “easy,” “difficult,” or “excessive” ranges of conditions of the Fort Knox and Human Sciences Laboratory studies. The great advantage of these criteria over others proposed is that the extent of the physiological strain on the workmen can be assessed, directly and simply, by a measurement of oral or rectal temperatures during the shift, and from these results limits for work can be set for work at specific hot jobs. assessment of the extent of physiological strain on workmen in heat; determination of physiological limits for work in hot conditions; sensitive and saturated control ranges in man's temperature regulation; relationships between rectal temperature and conductance and rectal temperature and sweat rate Submitted on March 20, 1964

Effect of cerebrospinal fluid hyperosmolality on sweating in the heat-stressed patas monkey

1989 ◽  
Vol 67 (1) ◽  
pp. 128-133 ◽  
Author(s):  
M. D. Owen ◽  
R. D. Matthes ◽  
C. V. Gisolfi
Keyword(s):  
Cerebrospinal Fluid ◽  
Rectal Temperature ◽  
Sweat Rate ◽  
Recovery Period ◽  
Erythrocebus Patas ◽  
Artificial Cerebrospinal Fluid ◽  
Skin Temperatures ◽  
Central Stimulation ◽  
Osmotic Stimuli

Dehydration increases the osmolality of body fluids and decreases the rate of sweating during thermal stress. By localizing osmotic stimuli to central nervous system tissues, this study assessed the role of central stimulation on sweating in a heat-stressed nonhuman primate. Lenperone-tranquilized patas monkeys (Erythrocebus patas n = 5), exposed to 41 +/- 2 degrees C, were monitored for calf sweat rate, rectal and mean skin temperatures, oxygen consumption, and heart rate during infusions (255–413 microliters) of hypertonic artificial cerebrospinal fluid (ACSF) into the third cerebral ventricle. ACSF made hypertonic with NaCl to yield osmolalities of 800 and 1,000 mosmol/kgH2O significantly decreased sweat rate compared with control ACSF (285 mosmol/kgH2O), achieving maximal reductions during infusion of 37 and 53%, respectively. Rectal temperature significantly increased during the recovery period, reaching elevations of 0.69 and 0.72 degrees C, respectively, at 20 min postinfusion. In contrast, ACSF made hypertonic with sucrose (800 mosmol/kgH2O) failed to change sweat rate or rectal temperature during infusion in three animals. Thus, intracerebroventricular infusions of hypertonic ACSF mimicked dehydration-induced effects on thermoregulation. The reduction in heat loss during infusion appeared to depend on an elevation in cerebrospinal fluid [Na+] and not osmolality per se.

Age and sex difference in response to short exposure to extreme dry heat

1978 ◽  
Vol 44 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Y. Shoenfeld ◽  
R. Udassin ◽  
Y. Shapiro ◽  
A. Ohri ◽  
E. Sohar
Keyword(s):  
Skin Temperature ◽  
Rectal Temperature ◽  
Short Exposure ◽  
Large Individual ◽  
Elderly Male ◽  
Dry Heat ◽  
Heat Response ◽  
Male Subjects ◽  
Skin Temperatures ◽  
Age And Sex

Sixty volunteers, 33 males and 27 females (18–63 yr), were divided according to age and sex. They were exposed for 10 min to extreme dry heat: 80–90 degrees C dry bulb temperature and 3–4% relative humidity. Their rectal temperature, skin temperature at eight different points, weight, and heart rate were recorded prior to and immediately following the exposure. A mean rise of only 0.5 degrees C in rectal temperature was recorded following exposure as compared to a mean rise of 5.2 degrees C in mean weighted skin temperature (MWST). Female subjects showed a significantly higher rise in MWST than the male subjects. Similarly, a significantly higher rise in MWST was observed in elderly male subjects as compared to the youngest male group (P less than 0.05). The differences in MWST possibly resulted from differences in mean skin blood flow causing differences in skin conductance. Large individual variation in heat response was recorded in rectal temperature, as well as in weighted skin temperatures. The increase in skin temperature during the first 10 min of exposure to extreme dry heat may serve as an indicator for heat tolerance time, and may help predicting heatstroke susceptible individuals.

Observations on the effect of salicylate in fever and the regulation of body temperature against cold

1976 ◽  
Vol 54 (2) ◽  
pp. 101-106 ◽  
Author(s):  
Q. J. Pittman ◽  
W. L. Veale ◽  
K. E. Cooper
Keyword(s):  
Body Temperature ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Intravenous Infusion ◽  
Sodium Salicylate ◽  
Single Injection ◽  
Continuous Intravenous Infusion ◽  
Skin Temperatures

Prostaglandins appear to be mediators, within the hypothalamus, of heat production and conservation during fever. We have investigated a possible role of prostaglandins in the nonfebrile rabbit during thermoregulation in the cold. Shorn rabbits were placed in an environment of 20 °C, and rectal and ear skin temperatures, shivering and respiratory rates were measured. A continuous intravenous infusion of leucocyte pyrogen was given to establish a constant fever of approximately 1 °C, and after observation of a stable febrile temperature for 90 min, a single injection of 300 mg of sodium salicylate, followed by a 1.5 mg/min infusion was then given. After the salicylate infusion was begun, rectal temperature began to fall, and reached nonfebrile levels within 90 min. Shivering activity ceased, respiratory rates increased, and in two animals, ear skin temperature increased. When these same rabbits were placed in an environment of 10 °C, at a time they were not febrile, and an identical amount of salicylate was given, rectal and ear skin temperatures, shivering and respiratory rates did not change. These results indicate that prostaglandins do not appear to be involved in heat production and conservation in the nonfebrile rabbit.

Responses of Zebu, Jersey, and Zebu X Jersey crossbred heifers to rising temperature, with particular reference to sweating

1962 ◽  
Vol 13 (1) ◽  
pp. 165 ◽  
Author(s):  
TE Allen
Keyword(s):  
Skin Temperature ◽  
Air Temperature ◽  
Rectal Temperature ◽  
Temperature Regime ◽  
Linear Increase ◽  
The Other ◽  
Sweating Rate ◽  
Respiration Rates ◽  
Breed Differences ◽  
Skin Temperatures

Zebu, Jersey, and Zebu x Jersey crossbred heifers were subjected to a rising temperature regime over the range 65 to 105°F. Sweating rates, respiration rates, skin temperatures, and rectal temperatures were measured. All breeds showed similar responses in skin temperature and rectal temperature to increase in air temperature. The increase in skin temperature was approximately linear with rise in air temperature. Rectal temperature did not commence to rise until an air temperature of 90°F and a skin temperature of 98° was reached. Breed differences in sweating and respiratory rates with increase in air and skin temperature were observed. The Jersey heifers showed an early and almost linear increase in sweating rate with rise in air and skin temperature, whereas the sweating rate of the Zebu heifers did not increase until air temperature had risen to at least 85°F and skin temperature to 95°. Two crossbreds began to increase their sweating rates at temperatures intermediate between those recorded for Zebus arid Jerseys. The remaining two behaved similarly to Jerseys. All three breeds showed similar maximum sweating rates in response to this rising temperature regime. The respiratory rate of' the Jerseys was higher than that of the Zebus at all temperatures, and particularly at high temperatures. Crossbreds respired at rates comparable to the Jerseys until an air temperature of 90°F and a skin temperature of 97°F were exceeded, when their respiration rates became intermediate between the other two breeds. The significance of these differences is discussed.

Effects of salicylate on acclimatization to work in the heat

1965 ◽  
Vol 20 (1) ◽  
pp. 70-72 ◽  
Author(s):  
David E. Bass ◽  
Eugene D. Jacobson
Keyword(s):  
Rectal Temperature ◽  
Sodium Salicylate ◽  
Sweat Rate ◽  
Drug Regimen ◽  
Control Group ◽  
Heat Acclimatization ◽  
Acute Response ◽  
Hot Environments ◽  
Qualitative Responses ◽  
Skin Temperatures

Some effects of daily large doses of sodium salicylate were studied on the pattern of acclimatization to work in the heat. Acclimatization was induced by daily walks of 100 min on a level treadmill at 3.5 mph at 120/80 F (dry bulb/wet bulb). Two matched groups of six men each were acclimatized in this manner and one group received 5.9–7.8 g of sodium salicylate daily over a period of 10 days. Men treated with salicylate exhibited the same qualitative responses as the control group in terms of the acclimatization process, i.e., their rectal temperatures, skin temperatures, and pulse rates during work in the heat were lower on the later days. Quantitatively, the degree of acclimatization (as measured by rectal temperature) was less in the men receiving salicylate than in the control group. This difference was more apparent than real, however, in that when the salicylate group were taken off the drug regimen, they exhibited the same degree of acclimatization in terms of rectal temperature as did the control group. The acclimatization process did not abolish the acute response to salicylate. body temperature regulation; exercise; simulated desert environment; simulated jungle environment; hyperthermia; rectal temperature, skin temperature, sweat rate, and pulse rate in hot environments; antipyretics Submitted on June 15, 1964

Physical regulation of temperature in Eskimos

1962 ◽  
Vol 17 (2) ◽  
pp. 326-332 ◽  
Author(s):  
Donald W. Rennie ◽  
Benjamin G. Covino ◽  
Murray R. Blair ◽  
K. Rodahl
Keyword(s):  
Rectal Temperature ◽  
Temperature Regulation ◽  
Cold Adaptation ◽  
Subcutaneous Fat ◽  
Water Bath ◽  
Controlled Conditions ◽  
Average Skin ◽  
Skin Temperatures ◽  
Cutaneous Vasoconstriction

Temperature regulation of Eskimos and non-Eskimos, exclusive of shivering, was compared over a range of controlled conditions that produced near-maximal sweating (room temp., 35 C) to maximal cutaneous vasoconstriction (23 C air or 33 C water bath). The Eskimos consistently produced 15-20 kcal/m2/hr more heat at rest. This may or may not be cold adaptation. In air warmer than 28 C their surfeit of heat resulted in higher tissue conductances, warmer skin, and greater sweating. In cooler air and 33 C water, the physical conductance of heat through tissues of the Eskimos remained 60% greater and resulted in warmer skin or a greater fall of rectal temperature. This can be accounted for on physical grounds, since the Eskimos had 1 cm less subcutaneous fat than did non-Eskimos. The value of high metabolism and high tissue conductance to fully clothed Eskimos would appear to be reflex vascular convection of heat to distal extremities, since average skin temperatures under their clothing are comparable to those of unclothed Eskimos in room temperatures exceeding 28 C. Submitted on August 17, 1961

Heat Strain in Protective Clothing Following Hot-Wet or Hot-Dry Heat Acclimation

1996 ◽  
Vol 21 (2) ◽  
pp. 90-108 ◽  
Author(s):  
Tom M. McLellan ◽  
Yukitoshi Aoyagi
Keyword(s):  
Heart Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Protective Clothing ◽  
Intermittent Exercise ◽  
Sweat Rate ◽  
Heat Acclimation ◽  
Heat Strain ◽  
Mean Skin Temperature ◽  
Time Required

The purpose of the present study was to compare the heat strain while wearing nuclear, biological, and chemical (NBC) protective clothing following a hot-wet (HW) or hot-dry (HD) heat acclimation protocol. Twenty-two males were assigned to groups HW (n = 7), HD (n = 8), or control (C, n = 7). Subjects were evaluated during continuous treadmill walking while wearing lightweight combat clothing and during intermittent exercise while wearing the NBC protective clothing. While wearing Combat clothing, greater decreases in rectal temperature (Tre), mean skin temperature [Formula: see text], and heart rate were observed for both acclimation groups. For the NBC clothing trials, lower Tre, [Formula: see text], and heart rates were observed only for group HW. The time required for Tre to increase 1.0 °C and 1.5 °C was significantly delayed for groups HW and HD. Sweat evaporation increased for HW, whereas no change was found for HD. The most significant changes in Tre, [Formula: see text], and heart rate while wearing the NBC protective clothing occur following heat acclimation that involves wearing the clothing during exercise. Key words: rectal temperature, mean skin temperature, heart rate, sweat rate

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