Human temperature regulation under heat stress in health, disease, and injury

Abstract

The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.

Skin-Interfaced Superhydrophobic Insensible Sweat Sensors for Evaluating Body Thermoregulation and Skin Barrier Functions

“…Stable core temperature homeostasis is essential for regulating metabolic rates and functions of the major organ systems . Key in the thermoregulation process, sweating with a large specific heat capacity can absorb and transfer body heat to the surrounding environment , by evaporative cooling − when the core body temperature exceeds the hyperthermic threshold. Compared with the sensible (liquid) sweat from the sweat glands during intensive activities/exercise, insensible (vapor) sweat is secreted through the skin at a much smaller rate under mild conditions (e.g., resting or low-intensity exercise). , Although skin-interfaced microfluidic devices with colorimetric or electrical components have been developed to detect sweat rate and loss, − they are limited to working with sensible sweat only and are not suitable for the insensible sweat in a vapor state. , Besides informing on the body’s thermoregulation status, the insensible sweat rate and loss can also help evaluate the skin barrier functions and nervous system activity. , The skin barrier function prevents excessive water evaporation to keep the skin hydrated. − Affected by emotional stimuli from the activities of sympathetic excitation, the insensible sweat can also be used to reflect underlying health status (e.g., chronic psychological stress, anxiety, or pain) .…”

Exertional heat stroke: pathophysiology and risk factors

“…Ageing in humans is accompanied by a decrease in sudomotor function, cardiovascular function, immune function, and behavioural thermoregulation. 15 These factors contribute to the increased risk of heat related morbidity and mortality. 109 Elderly people typically have a higher incidence of classic heat stroke than EHS because of decreased activity levels, and many older individuals also have pre-existing cardiovascular insufficiencies, as observed by a lower…”

Relationship between Fever Level and Leukocyte Levels in Children with Typhoid Fever

“…The hypothalamus, whose job it is to regulate the equilibrium between the body's heat production and heat loss, is the organ that is in charge of ensuring that the temperature of the body remains steady within a narrow band of acceptable variation. The hypothalamus is the part of the brain that is in charge of ensuring that the temperature of the human body remains at a steady 370 degrees Celsius when circumstances are normal (Cramer et al, 2022). In the event that there is a disparity between the pace at which the body generates heat and the rate at which it loses heat, this might result in a rise in set point that is too high.…”