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Neuroscience Letters Mar 2019Maintenance of mammalian core body temperature within a narrow range is a fundamental homeostatic process to optimize cellular and tissue function, and to improve... (Review)
Review
Maintenance of mammalian core body temperature within a narrow range is a fundamental homeostatic process to optimize cellular and tissue function, and to improve survival in adverse thermal environments. Body temperature is maintained during a broad range of environmental and physiological challenges by central nervous system circuits that process thermal afferent inputs from the skin and the body core to control the activity of thermoeffectors. These include thermoregulatory behaviors, cutaneous vasomotion (vasoconstriction and, in humans, active vasodilation), thermogenesis (shivering and brown adipose tissue), evaporative heat loss (salivary spreading in rodents, and human sweating). This review provides an overview of the central nervous system circuits for thermoregulatory reflex regulation of thermoeffectors.
Topics: Animals; Body Temperature; Body Temperature Regulation; Humans; Neural Pathways; Shivering; Skin Temperature; Thermogenesis
PubMed: 30586638
DOI: 10.1016/j.neulet.2018.11.027 -
Handbook of Clinical Neurology 2018Sleep in mammals is accompanied by a decrease in core body temperature (CBT). The circadian clock in the hypothalamic suprachiasmatic nucleus regulates daily rhythms in... (Review)
Review
Sleep in mammals is accompanied by a decrease in core body temperature (CBT). The circadian clock in the hypothalamic suprachiasmatic nucleus regulates daily rhythms in both CBT and arousal states, and these rhythms are normally coupled. Reductions in metabolic heat production resulting from behavioral quiescence and reduced muscle tone along with changes in autonomic nervous system activity and thermoeffector activity contribute to the sleep-related fall in CBT. Reductions in sympathetic tone to the peripheral vasculature resulting in heat loss through the skin are reflected in a sleep-related increase in distal skin temperature that is a prominent feature of sleep onset in humans. Within a sleep episode, patterns of autonomic nervous system and thermoeffector activity and the ability to defend against heat and cold exposure differ during nonrapid eye movement (NREM) and rapid eye movement sleep. Anatomic and functional integration of the control of arousal states and thermoregulation occur in the preoptic/anterior hypothalamus. Subsets or warm-sensing neurons in the preoptic/anterior hypothalamus implicated in CBT regulation are spontaneously activated during sleep onset and NREM sleep compared to waking and may underlie sleep-related changes in autonomic nervous system and thermoeffector activity.
Topics: Animals; Body Temperature; Body Temperature Regulation; Humans; Sleep
PubMed: 30454599
DOI: 10.1016/B978-0-444-63912-7.00020-5 -
Annals of the Academy of Medicine,... Apr 2008This review discusses human thermoregulation during exercise and the measurement of body temperature in clinical and exercise settings. The thermoregulatory mechanisms... (Review)
Review
This review discusses human thermoregulation during exercise and the measurement of body temperature in clinical and exercise settings. The thermoregulatory mechanisms play important roles in maintaining physiological homeostasis during rest and physical exercise. Physical exertion poses a challenge to thermoregulation by causing a substantial increase in metabolic heat production. However, within a non-thermolytic range, the thermoregulatory mechanisms are capable of adapting to sustain physiological functions under these conditions. The central nervous system may also rely on hyperthermia to protect the body from "overheating." Hyperthermia may serve as a self-limiting signal that triggers central inhibition of exercise performance when a temperature threshold is achieved. Exposure to sub-lethal heat stress may also confer tolerance against higher doses of heat stress by inducing the production of heat shock proteins, which protect cells against the thermolytic effects of heat. Advances in body temperature measurement also contribute to research in thermoregulation. Current evidence supports the use of oral temperature measurement in the clinical setting, although it may not be as convenient as tympanic temperature measurement using the infrared temperature scanner. Rectal and oesophagus temperatures are widely accepted surrogate measurements of core temperature (Tc), but they cause discomfort and are less likely to be accepted by users. Gastrointestinal temperature measurement using the ingestible temperature sensor provides an acceptable level of accuracy as a surrogate measure of Tc without causing discomfort to the user. This form of Tc measurement also allows Tc to be measured continuously in the field and has gained wider acceptance in the last decade.
Topics: Body Temperature; Body Temperature Regulation; Exercise; Humans; Monitoring, Physiologic
PubMed: 18461221
DOI: No ID Found -
Anesthesiology Aug 2008Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably... (Review)
Review
Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in patients not undergoing general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients undergoing general anesthesia exceeding 30 min in duration and in patients undergoing major operations during neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature, triggering cold defenses, including arteriovenous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, with the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extent than does general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.
Topics: Anesthesia, General; Body Temperature; Body Temperature Regulation; Humans; Hypothermia; Monitoring, Intraoperative; Shivering; Skin Temperature; Sweating
PubMed: 18648241
DOI: 10.1097/ALN.0b013e31817f6d76 -
Advances in Physiology Education Sep 2015Thermoregulation is the maintenance of a relatively constant core body temperature. Humans normally maintain a body temperature at 37°C, and maintenance of this... (Review)
Review
Thermoregulation is the maintenance of a relatively constant core body temperature. Humans normally maintain a body temperature at 37°C, and maintenance of this relatively high temperature is critical to human survival. This concept is so important that control of thermoregulation is often the principal example cited when teaching physiological homeostasis. A basic understanding of the processes underpinning temperature regulation is necessary for all undergraduate students studying biology and biology-related disciplines, and a thorough understanding is necessary for those students in clinical training. Our aim in this review is to broadly present the thermoregulatory process taking into account current advances in this area. First, we summarize the basic concepts of thermoregulation and subsequently assess the physiological responses to heat and cold stress, including vasodilation and vasoconstriction, sweating, nonshivering thermogenesis, piloerection, shivering, and altered behavior. Current research is presented concerning the body's detection of thermal challenge, peripheral and central thermoregulatory control mechanisms, including brown adipose tissue in adult humans and temperature transduction by the relatively recently discovered transient receptor potential channels. Finally, we present an updated understanding of the neuroanatomic circuitry supporting thermoregulation.
Topics: Adaptation, Physiological; Adult; Body Temperature; Body Temperature Regulation; Female; Fever; Humans; Hypothermia; Male; Sensitivity and Specificity; Shivering; Skin Temperature; Sweating; Thermoreceptors; Thermosensing
PubMed: 26330029
DOI: 10.1152/advan.00126.2014 -
Exercise and Sport Sciences Reviews Apr 2019Thermoregulation is accomplished via autonomic and behavioral responses. Autonomic responses may influence decisions to behaviorally thermoregulate. For instance, in... (Review)
Review
Thermoregulation is accomplished via autonomic and behavioral responses. Autonomic responses may influence decisions to behaviorally thermoregulate. For instance, in addition to changes in body temperature, skin wettedness and involuntary muscle contraction, which occur subsequent to sweating and shivering, likely modulate thermal behavior. This autonomic-behavioral interaction provides the rationale for our hypothesis that thermoregulatory behavior decreases the requirement for autonomic responses.
Topics: Autonomic Nervous System; Body Temperature; Body Temperature Regulation; Humans; Shivering; Skin Physiological Phenomena; Sweating
PubMed: 30632999
DOI: 10.1249/JES.0000000000000180 -
Neuroscience and Biobehavioral Reviews May 1998Emotional hyperthermia, circadian variations and the rise of body temperature related to exercise, have all been attributed to setpoint temperature shifts. The accepted... (Review)
Review
Emotional hyperthermia, circadian variations and the rise of body temperature related to exercise, have all been attributed to setpoint temperature shifts. The accepted theory holds that core temperature is regulated by corrective thermoregulatory responses opposing the core temperature deviations from the setpoint level. However, in fever and anapyrexia the thermoregulatory responses appear to be not corrective but helping, that is in the same direction as the core temperature deviation. A supplementary ad hoc hypothesis that setpoint level shifts explains why the thermoregulatory responses still could be considered "corrective" in spite of being in the same direction as the core temperature deviation. But supplementary ad hoc hypotheses immunize a theory to experimental challenges and therefore can no longer be considered a scientific theory. The present work shows that most of the arguments adduced to explain almost every biothermal phenomenon as being due to setpoint shifts cannot withstand a critical analysis.
Topics: Animals; Body Temperature; Body Temperature Regulation; Physical Exertion; Rats; Reference Values
PubMed: 9579330
DOI: 10.1016/s0149-7634(97)00051-1 -
Clinical and Experimental Pharmacology... Feb 19981. The effects of ethanol on body temperature (Tb) and on the regulator of Tb are reviewed. 2. The first section considers how ethanol affects cellular function and how... (Review)
Review
1. The effects of ethanol on body temperature (Tb) and on the regulator of Tb are reviewed. 2. The first section considers how ethanol affects cellular function and how temperature modifies these effects. 3. The next section reviews the effects of ethanol on Tb, covering both disruptive effects and effects on regulatory elements. 4. The final section covers recent work that has made use of genetic techniques to elucidate specific aspects of how ethanol affects temperature regulation.
Topics: Animals; Body Temperature; Body Temperature Regulation; Central Nervous System Depressants; Ethanol; Humans
PubMed: 9493506
DOI: 10.1111/j.1440-1681.1998.tb02195.x -
IEEE Journal of Biomedical and Health... May 2022Accurate and continuous measurement of the human core body temperature by a wearable device is of great significance for human health care and disease monitoring. The...
Accurate and continuous measurement of the human core body temperature by a wearable device is of great significance for human health care and disease monitoring. The current wearable thermometers ignore the physiological differences between individuals and the role of blood perfusion in thermoregulation, resulting in insufficient accuracy and limitations in terms of the measurement sites. This study proposed a novel personal model for measuring core body temperature by taking dynamic tissue blood perfusion and individual differences into consideration. The technique facilitates possible accurate core body temperature measurements from the skin surface of the wrist and forehead. First, the personal core body temperature model was established based on the thermal equilibrium between the human body and the measurement device, in which the tissue blood perfusion changes dynamically with tissue temperature. Then, the parameters of the personal model that imply individual physiological differences were obtained based on personal data collected daily. The results show that with the developed personal model, the accuracy of the measured body temperature from the wrist is close to that of the forehead model. The wrist model and the forehead model have a mean absolute error of 0.297 (SD = 0.078)°C and 0.224 (SD = 0.071)°C, respectively, which meets the accuracy and robustness requirements of practical applications. The personal models significantly improve the accuracy compared with that of the group model, especially for the wrist model.
Topics: Body Temperature; Humans; Individuality; Perfusion; Skin Temperature; Thermometers; Wearable Electronic Devices
PubMed: 34727042
DOI: 10.1109/JBHI.2021.3124551 -
Comparative Biochemistry and... May 2010Fever is an adaptive physiological response that animals use to fight infections by microorganisms. Although used routinely by veterinary and medical doctors for...
Fever is an adaptive physiological response that animals use to fight infections by microorganisms. Although used routinely by veterinary and medical doctors for assessment of health status, there are hardly any studies of fever in free-living animals. Body temperature in a sample of more than 500 adult barn swallows Hirundo rustica varied considerably, but was consistent among capture events. Body temperature increased during the day, and reached a minimum in the middle of the breeding season. A normal quantile plot revealed that 4.5% of adults constituted a separate population that had fever. There were only marginal effects of handling on body temperature. Body temperature increased by 2.6 standard deviations following injection with LPS, showing that body temperature indeed increased with an immune challenge. Body temperature was negatively related to abundance of feather mites, but was not related to abundance of other ectoparasites or size of the uropygial gland. Barn swallows with high body temperatures also had large body mass and showed weak stress responses as reflected by their tonic immobility. Barn swallows in large colonies had lower body temperatures than solitary or less colonial individuals. Body temperature was not related to arrival date, timing of breeding, annual fecundity or adult survival. However, individuals that were easier to catch had higher body temperatures. These findings suggest that body temperature is a consistent physiological parameter of individuals, a small fraction of individuals has fever, and that febrile individuals have specific parasite loads, body mass, social environment and ability to escape capture.
Topics: Animal Migration; Animals; Body Temperature; Body Temperature Regulation; Fever; Swallows
PubMed: 20188208
DOI: 10.1016/j.cbpb.2010.02.006