Human thermoregulation: separating thermal and nonthermal effects on the body's capacity to dissipate heat

人体体温调节：区分对身体散热能力的热效应和非热效应

• 批准号: RGPIN-2014-06313
• 负责人: Kenny, Glen
• 金额: $ 6.56万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=655332
• 关键词: Human; thermoregulation; separating; thermal; nonthermal

Temperature regulation is a vital aspect of human survival as relatively small deviations in internal body temperature can lead to profound disruptions in whole-body heat balance. Prolonged exposure to hot environments/processes and/or performing strenuous exercise can heat the body causing significant increases in internal body temperature. To offset this increase powerful and highly developed behavioral and autonomic thermoregulatory responses are activated to enhance whole-body heat loss. Inherent to this response is the concept of set-point about which internal body temperature is regulated. The body's temperature regulatory center is located in the hypothalamus of the central nervous system. Input to this center comes from temperature sensitive receptors in both the skin and the internal core regions of the body. Changes in skin and/or core temperature initiates a series of physiological actions aimed at enhancing heat dissipation. This heat is lost by contact with cool air and by sweat production, which cools your body as the sweat evaporates. However, when the body is unable to cool itself by sweating, several heat-induced illnesses such as heat stress or heat exhaustion and the more severe heat stroke can occur, and can result in death. Independent of thermal control (i.e., by changes in skin and/or core temperatures) of heat loss responses, there is increasing evidence demonstrating that nonthermal factors can have profound consequences on the body's ability to dissipate heat during heat stress. These nonthermal factors include those associated with the activation of the body's sensory receptors (i.e., baroreceptors, metaboreceptors, mechanoreceptors, etc.) as well as personal factors such as sex, aging, acclimation, etc. However, little is known about the mechanism underlying the nonthermal influence on human heat dissipation. My proposed study program is directed at understanding the separate and combined contribution of these factors during thermal challenges to human heat balance associated with elevations in environmental and metabolic (exercise) heat load. To achieve an advanced understanding of the role that nonthermal factors may play, we will study the mechanisms underlying the nonthermal modulation of the body's heat loss response from both a local and whole-body perspective. We will use the world's only whole-body calorimeter (a device for measuring heat emitted by the body) to precisely measure changes in the body's capacity to dissipate heat as function of these different factors. Moreover, in order to acquire a better understanding of the integration and coordination (interplay) of the human response to heat stress, the evaluation of thermoregulatory function will also be paralleled by the simultaneous measures of different physiological systems. By understanding the precise combination of environmental and metabolic heat loads where physiological differences in the body's capacity to dissipate heat occur in relation to these nonthermal factors, we can begin to develop a better understanding of how heat stress develops. Such information will have important practical benefits for many sectors of our society including the military, industry, sporting organizations and the general public. By understanding the interplay between thermal and nonthermal controllers on human thermoregulation, we can develop/improve management tools to control or eliminate heat stress conditions and protect the health and safety of individuals/workers during heat-stress conditions. Moreover, this knowledge can be used to stimulate the development of new technologies and solutions that will improve industry process efficiencies (e.g. ventilation and refrigeration, spot cooling techniques, new clothing designs, etc.).

温度调节是人类生存的重要方面，因为内体温度相对较小的偏差会导致全身热平衡的严重破坏。长时间暴露于热环境/过程和/或进行剧烈运动会加热人体，从而导致体内温度显着升高。 为了抵消这种增加的强大且高度发达的行为和自主神经调节反应，以增强全身热量损失。 这种响应固有的是对哪种内部体温进行调节的设定点的概念。人体的温度调节中心位于中枢神经系统的下丘脑中。 该中心的输入来自人体皮肤和内部核心区域的温度敏感受体。皮肤和/或核心温度的变化启动了一系列旨在增强热量耗散的生理作用。 通过与凉爽的空气接触和汗水产生，这种热量会损失，这会随着汗水蒸发而冷却您的身体。 但是，当人体无法通过出汗来冷却时，可能会出现几种热诱导的疾病，例如热应激或热量耗尽，并且可能会发生更严重的热中风，并可能导致死亡。与热损失反应的热控制无关（即，通过皮肤和/或核心温度的变化），有越来越多的证据表明，非热因素可能会对人体在热应激期间散发热量的能力产生深远的影响。 这些非热因素包括与人体感觉受体激活相关的因素（即，压力感受器，体形感受器，机械感受器等）以及性别，性，衰老，适应等的个人因素。但是，关于潜在机制的知识知之甚少对人类散热的非热影响。 我提出的研究计划旨在理解这些因素在热挑战对与环境和代谢（运动）热负荷高度相关的人类热量平衡时这些因素的单独和综合贡献。为了深入了解非热因素可能发挥的作用，我们将研究从局部和全身的观点上对人体热量丧失反应的非热调节的基础机制。 我们将使用世界上唯一的全身量热仪（用于测量人体发出的热量的设备）来精确衡量人体散发热量作为这些不同因素的功能的能力的变化。 此外，为了更好地了解人类对热应激的反应的整合和协调（相互作用），同时测量不同生理系统的评估，对热应力功能的评估也将平行。通过了解环境和代谢热负荷的精确组合，与这些非热因素有关，人体散发热量的生理差异就会出现，我们可以开始更好地了解热应激的发展方式。 这些信息将对我们社会的许多部门（包括军事，工业，体育组织和公众）具有重要的实际利益。 通过了解人类温度调节的热控制器和非热控制器之间的相互作用，我们可以开发/改善管理工具，以控制或消除热应激状况，并保护在热应激条件下个人/工人的健康和安全。 此外，这些知识可用于刺激新技术和解决方案的开发，以提高行业过程效率（例如通风和冷藏，现货冷却技术，新服装设计等）。