Mechanisms of Heat Exchange: Biophysics and Physiology

Abstract

The sections in this article are: 1 Human Heat Balance Equation 2 Independent Variables Affecting the Thermal Environment 2.1 Ambient Temperature 2.2 Dew Point Temperature and Ambient Vapor Pressure 2.3 Air and Fluid Movement 2.4 Mean Radiant Temperature and Effective Radiant Field 2.5 Clothing Insulation 2.6 Barometric Pressure 3 Peripheral Factors to Heat Exchange 3.1 Mean Skin Temperature 3.2 Skin Wettedness 3.3 Body Heat Storage and Rate of Change of Mean Body Temperature 3.4 Metabolic Energy 4 Sensible Heat Exchange by Radiation and Convection 4.1 Operative Temperature 4.2 Clothing Properties Effective in Sensible Heat Exchange 5 Radiation Exchange 5.1 Mean Radiant Temperature and Effective Radiant Field 6 Convective Heat Exchange 6.1 Heat Transfer Theory 6.2 Measurement of the Convective Heat Transfer Coefficient 6.3 Effect of Altitude (Barometric Pressure) on Convective Heat Loss 7 Evaporative Heat Exchange 7.1 Direct Measurement of Evaporative Heat Loss 7.1.1 Maximum Evaporative Heat Loss from the Human Skin Surface 8 Psychrometrics of the Human Heat Balance Equation 8.1 Lewis Relation: Interpretation of Wet-Bulb Temperature and Enthalpy 8.2 Generalization to Energy Transfer between Humans and the Environment 8.3 Enthalpy of the Human Environment 8.4 Enthalpy and the Rational Indices of the Human Environment 9 Pierce Two-Node Model of Thermoregulation 9.1 The Passive State 9.2 The Control System 9.3 Initial Warm and Cold Signals 9.4 Control of Skin Blood Flow 9.5 Control of the Whole-Body Sweating Drive 9.6 Control of the Skin Shell Properties 9.7 Control of Shivering 10 Heat Loss Factors in Warm and Cold Environments: Physiology 10.1 Heat and Mass Transfer from the Body to the Environment 10.2 Body Motion 10.2.1 Homeothermy 10.3 Thermal Aspects 10.3.1 Structural Modifications for Optimal Heat Loss 10.3.2 Characteristics of the Homeostatic Response 10.4 Thermoregulatory Control Relative to Heat Loss Factors 10.4.1 Metabolic Consequences 10.4.2 Central and Peripheral Nervous Systems 10.4.3 Thermoregulatory Changes 10.4.4 Exchange by Conduction-Convection and Adaptive Properties 10.4.5 Convective and Respiratory Heat Transfer and Adaptive Response 10.4.6 Evaporative Heat Loss and Adaptive Response 10.5 Physiological Responses of Heat Loss by Thermal Radiation and Adaptive Response 11 Heat Loss in Special Environments 11.1 Hypobaric Environments 11.2 Hyperbaric Environments 11.3 Aquatic Environments 11.4 Heat Exchange in Spacecraft