Abstract This work aims to develop a mathematical model for computing the distribution of temperature, O2, and CO2 in the human body, depending on the ambient conditions. The body is divided into segments, including layers of tissues and blood compartments, where mass and energy balances are applied. The inclusion of O2 and CO2 transfer mechanisms throughout all segments and tissues of the human body is one of the great novelties of this work. It also includes the exothermic metabolic reactions in the tissues, the transportation of O2 and CO2 by the blood, and the energy exchanged with the environment through the skin and by ventilation. The model also includes the regulation of metabolism, circulation, ventilation, and sweating, depending on the body temperature and the concentrations of O2 and CO2 in the blood. The lungs are represented by alveolar and blood compartments, with diffusion between them. Comparisons with experimental data from the existing literature show that the proposed model is suitable for representing transient exposure to cold and warm ambient temperatures, low concentration of O2, and high concentrations of CO2. In the end, some results demonstrate the effect of ambient temperature on the distribution of temperature, O2, and CO2 across segments, blood, and tissues. Shivering in a cold environment reduces the concentration of O2 and increases the concentration of CO2 in the muscles, which results in increased ventilation and blood circulation. The concentration of gases in the skin depends mainly on variations in the skin's circulation with the environment, which alters the availability of O2 and the elimination of CO2. Small variations were found in the concentrations of O2 and CO2 in the brain and lungs.

中文翻译：

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人体体温调节和呼吸系统的综合模型

摘要 这项工作旨在开发一种数学模型，用于根据环境条件计算人体内温度、O2 和 CO2 的分布。身体分为多个部分，包括组织层和血液隔室，在那里应用质量和​​能量平衡。在人体的所有部分和组织中包含 O2 和 CO2 传输机制是这项工作的一大创新。它还包括组织中的放热代谢反应，血液对O2和CO2的运输，以及通过皮肤和通风与环境交换的能量。该模型还包括根据体温和血液中 O2 和 CO2 浓度对新陈代谢、循环、通风和出汗的调节。肺由肺泡和血液室代表，它们之间有扩散。与现有文献中的实验数据进行比较表明，所提出的模型适用于表示对冷暖环境温度、低浓度 O2 和高浓度 CO2 的瞬态暴露。最后，一些结果证明了环境温度对温度、O2 和 CO2 跨节段、血液和组织的分布的影响。在寒冷的环境中发抖会降低 O2 的浓度并增加肌肉中的 CO2 浓度，从而增加通风和血液循环。皮肤中气体的浓度主要取决于皮肤循环随环境的变化，这会改变 O2 的可用性和 CO2 的消除。