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Temperature and Chemicals
Published in Sue Binkley, Biological Clocks, 2020
Warm-blooded animals (the birds and mammals, homeotherms) maintain body temperatures around 37°C. There are circadian fluctuations in body temperature (about 1°C in a human, as much as 5°C in a house sparrow). Birds have higher body temperatures than mammals. Some homeotherms are able to drop their body temperatures on a nightly (daily torpor) or a seasonally (hibernation).85
Evolutionary Aspects
Published in Shojiro Inoué, Biology of Sleep Substances, 2020
The evolution of sleep has differentiated the sleep-like state in lower vertebrates into slow-wave sleep (SWS) and paradoxical sleep (PS) in homeotherms.4 The immobilization and remobilization processes of PS seem to be closely related to the archaic type of sleep. Deep sleep, especially the deep stages of nonrapid-eye-movement (non-REM) sleep, might be required to restitute the highly developed cerebrum as a specially differentiated pattern of cerebral rest.5 Since higher vertebrates have established warm-bloodedness, rest-activity rhythms may not be absolutely dependent on the environmental temperature. Rather, the rhythms should be controlled by the internal environmental situation depending on the various physiological, psychological, and ecological conditions. Since homeotherms cannot drastically lower their body temperature, temperature regulation, coupled with sleep regulation, has become vitally important for controlling energy expenditure. Thus, the function of sleep has become more and more specialized and diversely differentiated. It seems likely that the multivariate functions of sleep may require multiple humoral factors in addition to the hierarchical organization of the central nervous system.
Effects of Heat on Blood Flow
Published in Leopold J. Anghileri, Jacques Robert, Hyperthermia in Cancer Treatment, 2019
There is a rich literature developed by scientists of many disciplines concerning systemic thermal regulation in response to both high and low temperature environments.56,57 Certainly their insights would aid any investigator attempting to formulate a strategy for the optimal use of therapeutic hyperthermia. As a homeotherm, it is necessary that man respond to local or systemic heating with a physiological response capable of dissipating enough heat to return the body to its normal temperature. Man’s thermal regulatory response to systemic heating is directed from the hypothalamus and involves sweating and an increase of cardiac output accompanied by a shunting of blood to peripherally vasodilated cutaneous vessels. While sweating is essentially a centrally mediated phenomenon, a significant degree of vasodilation can occur after transection of afferent and efferent neuro pathways.58
Preoptic bombesin-like receptor-3 neurons heat it up
Published in Temperature, 2022
Ramón A. Piñol, Marc L. Reitman
The POABRS3 neurons are involved in the thermoregulatory functions of BAT and the cardiovascular system. Since the discovery of functional BAT in humans, there is increased interest in central pathways that regulate BAT. While infants rely on BAT for thermogenesis, later in life there is little BAT thermogenesis in most people. BAT activation is potentially beneficial in obese patients, since it can improve glucose regulation and cardiovascular health, in addition to increasing energy expenditure. Therefore, BAT activation is a conceivable therapy in patients with obesity or diabetes. Hence, detailed knowledge of central circuits of BAT and Tb regulation in mice contributes to better understanding our own physiology in health and disease. The newly identified functions of the POABRS3 neurons provide a glimpse into the complexity of neural circuitry network controlling Tb and BAT. It is exciting to apply modern tools of neurobiology to study this ancient, conserved physiology. These insights will contribute to the understanding of homeothermy, a defining characteristic of mammalian biology.
Human thermal perception and time of day: A review
Published in Temperature, 2021
Marika Vellei, Giorgia Chinazzo, Kirsi-Marja Zitting, Jeffrey Hubbard
Humans, like nearly all mammals and avian species, are homeotherms (warm-blooded), meaning that their internal body temperature remains stable irrespective of environmental influence [26]. This is in contrast to poikilotherms (cold-blooded), such as fish, reptiles, and amphibians, whose internal temperature fluctuates widely depending on different factors, and can both influence metabolic rate and radically alter cellular processes (i.e. protein denaturing at high temperature) [27]. In the past, thermoregulation was thought to be exclusively under the control of the preoptic hypothalamus, a brain region located posterior to the optic nerve, and ventral to cortical structures [28]. Generally speaking, the hypothalamus is responsible for the regulation of a wide array of autonomic functions, including appetite and sleep initiation, and forms a critical part of the hypothalamic-pituitary-adrenal axis, which controls among others, stress reactions. In recent years, however, its role in regards to being the sole controller of thermoregulation in the brain has been redefined [29]. For example, thermoreceptors have been found in other areas, including the brain stem, and indeed in other central nervous system structures such as the spinal cord [30], underscoring the fact that the thermoregulatory system is diffuse [31].
Effect of regular swimming exercise to duration-intensity on neurocognitive function in cerebral infarction rat model
Published in Neurological Research, 2019
Min-Keun Song, Eun-Jong Kim, Jung-Kook Kim, Hyeng-Kyu Park, Sam-Gyu Lee
The photothrombotic cerebral infarction rat model was set up as previously described by Watson and colleagues [12]. Each rat was anesthetized with 5% isoflurane, and anesthesia was maintained with 2% isoflurane in a 70% nitrous oxide and 30% oxygen mixture during the experimental procedure. The operation was performed on a homeothermic plate (Harvard Apparatus, South Natick, USA) in order to maintain body temperature at 37.5 ± 0.5°C. The anesthetized rat was put in prone position on a stereotactic frame (Stoelting, Wood Dale, USA). Following exposure of the scalp, 50 mg/kg Rose Bengal dye (Sigma-Aldrich Co, St. Louis, USA) was administered into the left femoral vein, and light exposure (KL 1500 LCD, SCHOTT; Hattenbergstrasse, Germany; 3300 K, 150 W) was applied for 20 min to the left parietal area corresponding to the forelimb area of the primary sensorimotor cortex.