Bioheat Transfer Basis of Human Thermoregulation: Principles and Applications

Abstract Thermoregulation is a process that is essential to the maintenance of life for all warm-blooded mammalian and avian species. It sustains a constant core body temperature in the face of a wide array of environmental thermal conditions and intensity of physical activities that generate internal heat. A primary component of thermoregulatory function is the movement of heat between the body core and the surface via the circulation of blood. The peripheral vasculature acts as a forced convection heat exchanger between blood and local peripheral tissues enabling heat to be conducted to the skin surface where is may be transferred to and from the environment via conduction, convection, radiation, and/or evaporation of water as local conditions dictate. Humans have evolved a particular vascular structure in glabrous (hairless) skin that is especially well suited for heat exchange. These vessels are called arteriovenous anastomoses (AVAs) and can vasodilate to large diameters and accommodate high flow rates. We report herein a new technology based on a physiological principle that enables simple and safe access to the thermoregulatory control system that allow manipulation of thermoregulatory function. The technology operates by applying a small amount of heating local to control tissue on the body surface overlying the cerebral spine that upregulates AVA perfusion. Under this action, heat exchangers can be applied to glabrous skin, preferably on the palms and soles, to alter the temperature of elevated blood flow prior to its return to the core. Therapeutic and prophylactic applications are discussed.

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Thermal Comfort and Energy Use with Local Heaters

Energies ◽

10.3390/en13112912 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2912

Author(s):

Jan Kaczmarczyk ◽

Joanna Ferdyn-Grygierek

Keyword(s):

Thermal Comfort ◽

Energy Use ◽

Human Subjects ◽

Local Heating ◽

Internal Heat ◽

Thermal Conditions ◽

Heating System ◽

Local Conditions ◽

Heating Systems ◽

Low Efficiency

This paper presents the investigation of a local heating system consisting of three heating mats incorporated within a sedentary workplace. Thermal comfort and individual power settings for the heating mats were studied in experiments with 41 human subjects. Experiments were performed in a climate chamber at two operative temperatures: 16 and 18 °C. Results showed that local heating systems improved occupants’ comfort and were able to create acceptable thermal conditions under both temperatures. The power settings identified were used to study the applicability of heating mats in an industrial hall. Multi-variant analysis of energy consumption for heating was carried out using an ESP-r (Environmental Systems Performance–Research) simulation program. The analysis results demonstrate that in some cases, the installation of local heating mats in industrial halls may reduce energy usage compared to having to heat the entire hall. However, the benefits depend on numerous parameters. Local heating is most advantageous when installed in halls with a small number of workstations, small internal heat gains, and low-efficiency central heating systems. In reality for the satisfactory implementation of local heating systems for a particular application, it is advised to perform analysis for the specific local conditions. In order to improve the effectiveness of local heating systems, an advanced heating control strategy should be considered.

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Thermal conditions experienced during differentiation affect metabolic and contractile phenotypes of mouse myotubes

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00148.2016 ◽

2016 ◽

Vol 311 (3) ◽

pp. R457-R465 ◽

Cited By ~ 8

Author(s):

Alex G. Little ◽

Frank Seebacher

Keyword(s):

Body Temperature ◽

Cold Exposure ◽

Metabolic Flux ◽

Core Body Temperature ◽

Thermal Conditions ◽

Glycolytic Flux ◽

Peripheral Tissues ◽

Atp Production ◽

Metabolic Role ◽

Core Body

Central pathways regulate metabolic responses to cold in endotherms to maintain relatively stable internal core body temperatures. However, peripheral muscles routinely experience temperatures lower than core body temperature, so that it would be advantageous for peripheral tissues to respond to temperature changes independently from core body temperature regulation. Early developmental conditions can influence offspring phenotypes, and here we tested whether developing muscle can compensate locally for the effects of cold exposure independently from central regulation. Muscle myotubes originate from undifferentiated myoblasts that are laid down during embryogenesis. We show that in a murine myoblast cell line (C2C12), cold exposure (32°C) increased myoblast metabolic flux compared with 37°C control conditions. Importantly, myotubes that differentiated at 32°C compensated for the thermodynamic effects of low temperature by increasing metabolic rates, ATP production, and glycolytic flux. Myotube responses were also modulated by the temperatures experienced by “parent” myoblasts. Myotubes that differentiated under cold exposure increased activity of the AMP-stimulated protein kinase (AMPK), which may mediate metabolic changes in response cold exposure. Moreover, cold exposure shifted myosin heavy chains from slow to fast, presumably to overcome slower contractile speeds resulting from low temperatures. Adjusting thermal sensitivities locally in peripheral tissues complements central thermoregulation and permits animals to maintain function in cold environments. Muscle also plays a major metabolic role in adults, so that developmental responses to cold are likely to influence energy expenditure later in life.

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Pathophysiology of Fever and Application of Infrared Thermography (IRT) in the Detection of Sick Domestic Animals: Recent Advances

Animals ◽

10.3390/ani11082316 ◽

2021 ◽

Vol 11 (8) ◽

pp. 2316

Author(s):

Daniel Mota-Rojas ◽

Dehua Wang ◽

Cristiane Gonçalves Titto ◽

Jocelyn Gómez-Prado ◽

Verónica Carvajal-de la Fuente ◽

...

Keyword(s):

Body Temperature ◽

Infrared Thermography ◽

Core Body Temperature ◽

The Body ◽

Farm Animals ◽

Economic Losses ◽

Febrile Response ◽

Temperature Range ◽

Stable Temperature ◽

Core Body

Body-temperature elevations are multifactorial in origin and classified as hyperthermia as a rise in temperature due to alterations in the thermoregulation mechanism; the body loses the ability to control or regulate body temperature. In contrast, fever is a controlled state, since the body adjusts its stable temperature range to increase body temperature without losing the thermoregulation capacity. Fever refers to an acute phase response that confers a survival benefit on the body, raising core body temperature during infection or systemic inflammation processes to reduce the survival and proliferation of infectious pathogens by altering temperature, restriction of essential nutrients, and the activation of an immune reaction. However, once the infection resolves, the febrile response must be tightly regulated to avoid excessive tissue damage. During fever, neurological, endocrine, immunological, and metabolic changes occur that cause an increase in the stable temperature range, which allows the core body temperature to be considerably increased to stop the invasion of the offending agent and restrict the damage to the organism. There are different metabolic mechanisms of thermoregulation in the febrile response at the central and peripheral levels and cellular events. In response to cold or heat, the brain triggers thermoregulatory responses to coping with changes in body temperature, including autonomic effectors, such as thermogenesis, vasodilation, sweating, and behavioral mechanisms, that trigger flexible, goal-oriented actions, such as seeking heat or cold, nest building, and postural extension. Infrared thermography (IRT) has proven to be a reliable method for the early detection of pathologies affecting animal health and welfare that represent economic losses for farmers. However, the standardization of protocols for IRT use is still needed. Together with the complete understanding of the physiological and behavioral responses involved in the febrile process, it is possible to have timely solutions to serious problem situations. For this reason, the present review aims to analyze the new findings in pathophysiological mechanisms of the febrile process, the heat-loss mechanisms in an animal with fever, thermoregulation, the adverse effects of fever, and recent scientific findings related to different pathologies in farm animals through the use of IRT.

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Growth and development of children under 5 years of age with tetralogy of Fallot in a Chinese population

Scientific Reports ◽

10.1038/s41598-021-93726-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xin Li ◽

Jin Zhu ◽

Jun An ◽

Yuqing Wang ◽

Yili Wu ◽

...

Keyword(s):

Body Weight ◽

Tetralogy Of Fallot ◽

Growth Retardation ◽

Growth And Development ◽

Heart Defects ◽

Body Height ◽

Child Growth ◽

The Body ◽

Early Age ◽

Local Conditions

AbstractCongenital Heart Defects (CHDs) are associated with different patterns of malnutrition and growth retardation, which may vary worldwide and need to be evaluated according to local conditions. Although tetralogy of Fallot (TOF) is one of the first described CHDs, the etiology outcomes in growth and development of TOF in early age child is still unclear in most cases. This study was designed to investigate the growth retardation status of Chinese pediatric TOF patients under 5 years old. The body height, body weight and body mass index (BMI) of 262 pediatric patients (138 boys and 124 girls) who underwent corrective surgery for TOF between 2014 and 2018 were measured using conventional methods. The average body height, body weight and BMI of the patients were significantly lower than WHO Child Growth Standards, while the most affected was body height. Meanwhile, higher stunting frequency and greater deterioration of both the body height and weight happened in elder age (aged 13–60 months) rather than in infant stage (aged 0–12 months) among these patients. Our results confirmed that intervention should be given at early age to prevent the growth retardation of TOF patients getting severer.

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A Computational Study on the Role of Parameters for Identification of Thyroid Nodules by Infrared Images (and Comparison with Real Data)

Sensors ◽

10.3390/s21134459 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4459

Author(s):

José R. González ◽

Charbel Damião ◽

Maira Moran ◽

Cristina A. Pantaleão ◽

Rubens A. Cruz ◽

...

Keyword(s):

Heat Transfer ◽

Thyroid Nodules ◽

Numerical Study ◽

Computational Study ◽

Internal Heat ◽

Heat Transfer Process ◽

The Body ◽

Physical Parameters ◽

Infrared Sensors ◽

Wide Range

According to experts and medical literature, healthy thyroids and thyroids containing benign nodules tend to be less inflamed and less active than those with malignant nodules. It seems to be a consensus that malignant nodules have more blood veins and more blood circulation. This may be related to the maintenance of the nodule’s heat at a higher level compared with neighboring tissues. If the internal heat modifies the skin radiation, then it could be detected by infrared sensors. The goal of this work is the investigation of the factors that allow this detection, and the possible relation with any pattern referent to nodule malignancy. We aim to consider a wide range of factors, so a great number of numerical simulations of the heat transfer in the region under analysis, based on the Finite Element method, are performed to study the influence of each nodule and patient characteristics on the infrared sensor acquisition. To do so, the protocol for infrared thyroid examination used in our university’s hospital is simulated in the numerical study. This protocol presents two phases. In the first one, the body under observation is in steady state. In the second one, it is submitted to thermal stress (transient state). Both are simulated in order to verify if it is possible (by infrared sensors) to identify different behavior referent to malignant nodules. Moreover, when the simulation indicates possible important aspects, patients with and without similar characteristics are examined to confirm such influences. The results show that the tissues between skin and thyroid, as well as the nodule size, have an influence on superficial temperatures. Other thermal parameters of thyroid nodules show little influence on surface infrared emissions, for instance, those related to the vascularization of the nodule. All details of the physical parameters used in the simulations, characteristics of the real nodules and thermal examinations are publicly available, allowing these simulations to be compared with other types of heat transfer solutions and infrared examination protocols. Among the main contributions of this work, we highlight the simulation of the possible range of parameters, and definition of the simulation approach for mapping the used infrared protocol, promoting the investigation of a possible relation between the heat transfer process and the data obtained by infrared acquisitions.

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Cortisol – inspection in the physiology and stress

Diagnostyka Laboratoryjna ◽

10.5604/01.3001.0013.7553 ◽

2018 ◽

Vol 54 (1) ◽

pp. 29-36

Author(s):

Nikola Musiała ◽

Iga Hołyńska-Iwan ◽

Dorota Olszewska-Słonina

Keyword(s):

Wide Spectrum ◽

Hormone Secretion ◽

Laboratory Diagnosis ◽

The Body ◽

Stress Hormone ◽

Renal Handling ◽

Peripheral Tissues ◽

Neurotransmitter Secretion ◽

Fatty Acids Metabolism ◽

System Functioning

Cortisol, also called “the” stress hormone is a glucocorticoid secreted by the adrenal cortex. This hormone plays a significant role in maintaining homeostasis, according to the body’s total stress. Cortisol interferes with many organs, affects glucose and fatty acids metabolism and neurotransmitter secretion. Predominantly, cortisol influences the carbohydrate metabolism, stimulating gluconeogenesis in the liver and inhibiting glucose utilization in peripheral tissues. As it is an element “fight or flight” it also stimulates central nervous system and enhances blood flow. To some extent cortisol influences also the renal handling of electrolytes, namely: increasing sodium resorption, and renal excretion of potassium, calcium and phosphates. Through its anti-inflammatory and immunosuppressive character this glucocorticoid modulates the immune system functioning. Cortisol has a circadian rhythm following ACTH (adrenocorticotropic hormone) secretion. Increased cortisol levels are observed physiologically during stress and pathologically in Cushing’s syndrome. Chronic hypercortisolism is harmful or the body, and its effects present an extremely wide spectrum, including insulin resistance, obesity, insomnia and even depression. Thus, laboratory diagnosis of cortisol level is important for the diagnosis, monitoring and evaluate the effectiveness of hypercortisolism treatment.

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Tree-Ring Growth of Larch (Larix decidua Mill.) in the Polish Sudetes—The Influence of Altitude and Site-Related Factors on the Climate–Growth Relationship

Forests ◽

10.3390/f9110663 ◽

2018 ◽

Vol 9 (11) ◽

pp. 663 ◽

Cited By ~ 2

Author(s):

Małgorzata Danek ◽

Monika Chuchro ◽

Adam Walanus

Keyword(s):

Tree Ring ◽

Climatic Factors ◽

Negative Relationship ◽

Thermal Conditions ◽

Cambial Activity ◽

Negative Influence ◽

Larix Decidua ◽

Related Factors ◽

Local Conditions ◽

Negative Effect

In this paper, the first study of a regional character on the influence of climatic factors on the tree-ring growth of European larch (Larix decidua Mill.) growing in the Polish Sudetes is presented. The obtained results indicate the relatively high diversity of the climatic signal observed in the tree rings of larches growing in the Sudetes. The most significant differentiating factor is altitude. The results suggest that the possible influence of local conditions (e.g., summit proximity, soil and bedrock characteristics, and exposure to strong winds) could also be of importance. A positive relationship between tree-ring growth and May temperatures was noted throughout the area; this indicates the principal importance of thermal conditions during the initial stage of cambial activity and tree-ring formation in larches from the Sudetes. The negative effect of the temperatures in the previous summer upon the tree-ring growth of larch in the subsequent year was also observed. The studies also indicate the negative influence of the water stress in summer (particularly in July of the previous year) upon the growth of trees. The negative relationship between tree-ring growth and the previous November temperature could be explained by the need for a late-autumn cooling, which affects the development of assimilation apparatus in spring of the subsequent year, which indirectly affects the tree-ring growth in the same year.

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Comparison of Tympanic and Tail Temperatures in Angus and Brahman Steers

Journal of Animal Science and Research ◽

10.16966/2576-6457.147 ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Dikmen S ◽

Davila KMS ◽

Rodriquez E ◽

Scheffler TL ◽

Oltenacu PA ◽

...

Keyword(s):

Body Temperature ◽

Repeated Measures ◽

Core Body Temperature ◽

The Body ◽

Tympanic Temperature ◽

Repeated Measure ◽

Important Indicator ◽

Significant Difference ◽

Brahman Steers ◽

Core Body

In cattle, core body temperature can be used as an important indicator of heat stress level. However, accurately recording core body temperature can be difficult and labor intensive. The objectives of the current study were 1) to compare the recorded tympanic and tail body temperature measurements in steers and 2) to determine the body temperature change of Angus and Brahman steers in a hot and humid environment. Data was analyzed using a repeated measure model where repeated measures were hourly tympanic and tail temperatures and their difference for individual steers during the day of the experiment. There was a significant breed effect (P=0.01), hour (P<0.0001) and breed by hour interaction (P<0.0001) for the tympanic temperature. Brahman steers, which are known to have superior thermotolerance, maintained a lower body temperature than the Angus steers during the afternoon under grazing conditions. In the Brahman steers there was only a minimal increase in the body temperature throughout the day, an evidence of the thermotolerance ability of the breed. In the Angus steers, which experienced an increase in their body temperature from hour to hour with a peak around 1600 hour; there was a significant difference between the tympanic and tail temperature during the times when the body temperature as measured by the tympanic recordings was the highest (1300 to 1700 hour). Our results indicate that the tympanic temperature can be used to accurately and continuously monitor core body temperature in a natural environment for up to several days and without disturbing the animal.

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Field Study Of A Radiant Heating System For Sleep Thermal Comfort And Potential Energy Saving

10.32920/ryerson.14654967 ◽

2021 ◽

Author(s):

Christopher L. K. Wang

Keyword(s):

Potential Energy ◽

Thermal Comfort ◽

Energy Saving ◽

Energy Savings ◽

Thermal Environment ◽

Residential Buildings ◽

Thermal Conditions ◽

Heating System ◽

The Body ◽

Radiant Temperature

As sleep is unconscious, the traditional definition of thermal comfort with conscious judgment does not apply. In this thesis sleep thermal comfort is defined as the thermal condition which enables sleep to most efficiently rejuvenate the body and mind. A comfort model was developed to stimulate the respective thermal environment required to achieve the desired body thermal conditions and a new infrared sphere method was developed to measure mean radiant temperature. Existing heating conditions according to building code conditions during sleeping hours was calculated to likely overheat a sleeping person and allowed energy saving potential by reducing nighttime heating set points. Experimenting with existing radiantly and forced air heated residential buildings, it was confirmed that thermal environment was too hot for comfortable sleep and that the infrared sphere method shows promise. With the site data, potential energy savings were calculated and around 10% of energy consumption reduction may be achieved during peak heating.

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A Case Report on Osborn Waves of Hypothermia Induced LV Systolic Dysfunction

International Journal of Pharmaceutical Sciences Review and Research ◽

10.47583/ijpsrr.2021.v70i02.004 ◽

2021 ◽

Vol 70 (2) ◽

Author(s):

Rajnandini Singha ◽

Amazing Grace Siangshai ◽

Jashlyn Lijo

Keyword(s):

Body Temperature ◽

Sinus Bradycardia ◽

Core Body Temperature ◽

Systolic Dysfunction ◽

Left Ventricular ◽

The Body ◽

Qrs Complex ◽

Pr Interval ◽

Gradual Expansion ◽

Core Body

Hypothermia, described as a core body temperature of < 95%, is associated with ECG alteration abnormalities. Sinus bradycardia occurs when the body temperature drops below 90°F, and is correlated with gradual prolongation of the PR interval, QRS complex, QT interval. It can progress to ventricular and atrial fibrillation at a temperature reaching 89°F, which can lead to left ventricular dysfunction. Hypothermia is connected to the osborn waves, which at the end of the QRS complex consist of additional deflection. The inferior and lateral precordial leads are seen by Osborn waves, also known as J waves, Camel hump waves and hypothermic waves. As the body temperature decreases, it becomes more pronounced and a gradual expansion of the QRS complex raises the likelihood of ventricular fibrillation causing ventricle dysfunction.

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