Thermoregulation refers to all the regulatory processes involved in maintaining body temperature. Warm-blooded animals maintain a constant temperature, regardless of outside temperatures. The center of thermoregulation is the hypothalamus.
What is thermoregulation?
Thermoregulation refers to all the regulatory processes involved in maintaining body temperature. Warm-blooded animals must maintain their body temperature because the various systems and bodily processes in their organism are directed toward a specific ideal temperature. Humans have a body temperature of 37 degrees Celsius relatively independent of outside temperatures. At these temperatures, an ideal temperature environment exists for his body processes. Like all other warm-blooded organisms, humans rely on regulatory processes to maintain constant body temperatures. These processes are summarized as thermoregulation or heat regulation. Depending on external temperatures, the organism initiates different processes as part of thermoregulation, such as cold shivering, sweating, metabolic adjustments, or fat burning. Heat regulation is not subject to voluntary control and is completely automated. A physiological control circuit is available for this purpose. Its first instance is represented by the thermoreceptors. The detected temperature information is transmitted by the receptors to the thalamus in the central nervous system. The hypothalamus connected to it is the actual center of thermoregulation. From this part of the central nervous system, commands are sent out into the body that have a regulatory effect on body temperature.
Function and task
The human body is in constant heat exchange with the environment through conduction, convection, radiation, and evaporation. The individual exchange mechanisms simultaneously initiate heat loss and passive heating. When the two are no longer in balance, the organism must respond with regulation to maintain a constant body temperature. The human body constantly produces heat in the thermogenesis of muscles and metabolism. It is relatively well insulated from the environment by subcutaneous fat tissue. In addition, it has the ability to lower its temperature, which is a mandatory requirement of the constantly occurring thermogenesis. The thermoreceptors bind permanently and involuntarily to temperature stimuli. The sensory cells of the sense of touch are located not only on the superficial skin, but also in the tissues and especially the mucous membranes. They project the measured temperatures via the thalamus to the hypothalamus, where they are evaluated and, if necessary, responded to with regulatory processes. When outside temperatures are low, the hypothalamus increases the tone of the sympathetic nervous system, which results in a wide variety of processes with the effect of heat conservation and heat production. For example, a temperature gradient is initiated. From the core of the body and the organs of the head, thoracic cavity and abdominal cavity, the temperature in the peripheral tissues drops with respect to the environment, so especially in the muscles of the periphery. Within the outer layer of the body, the blood supply decreases. Thus, the supply of heat with blood from metabolically active tissues is reduced. In this way, the periphery insulates the core of the body, so to speak. Peripheral blood vessels become less perfused to minimize heat loss through the blood. The skin pores contract for the same purpose. They also initiate goose bumps. The erect hairs create a small insulating layer of air through which radiating body heat escapes more slowly. In extreme cold, muscle tremors are also initiated. Muscle work causes heat to build up. For this reason, muscles are involuntarily stimulated to contract. However, cold shivering is only efficient in moderation. For this reason, it usually only starts when there is an acute risk of hypothermia. Significantly more efficient is the burning of brown adipose tissue initiated by cold. Therefore, heat-blooded animals primarily use combustion processes as regulatory measures in cold conditions. Outdoor temperatures also show effects on metabolic activity, which is primarily hormonally influenced by the hypothalamus. Metabolism is automatically increased in cold temperatures because increased metabolic rates produce heat. In heat, the hypothalamus reduces the tone of the sympathetic nervous system.Metabolism is then down-regulated to avoid producing additional heat. The vessels dilate to stimulate heat loss via the blood. However, the most important heat regulation for humans in hot outdoor temperatures is sweat evaporation. The sweat glands are automatically stimulated to increase fluid secretion in hot conditions, and the evaporation of sweat exhibits a cooling effect on the body.
Diseases and ailments
Heat regulation can be affected by disorders due to medications and deficiencies. Inappropriate sweating in cold temperatures and cold shivering despite heat can be the result. In addition, various diseases of the nervous system can disrupt the regulatory chain, especially in the case of injuries to the thalamus, hypothalamus or their projection pathways. Lesions in the area of the sympathetic nervous system can also be responsible for dysregulations in the metabolism or in the muscles, which affect the processes of thermoregulation. Diseases of sweat glands or metabolic diseases can be equally guilty of dysregulation. The same applies to diseases of endocrine glands, such as the anterior pituitary lobe. In phenomena such as heat stroke, temperature regulation fundamentally fails. The balance of heat regulation is thrown out of whack by heat damage to cells and organelles. Heat stroke is often preceded by increased heat production, e.g. through extreme sports in hot temperatures. In heat stroke with core body temperatures of 40 degrees Celsius, the enzyme system is damaged. The thermoregulatory mechanisms usually fail completely in this phenomenon. This often results in an uncontrolled rise in temperature, which in the final consequence may even cause necrosis or multi-organ failure. In general, abnormal temperature sensation is not directly equivalent to disorders of thermoregulation. Temperature sensation is individual and depends on many factors that are not necessarily associated with disease value.
