The Temperature sensation (med. Thermal reception) of the skin and the mucous membranes is guaranteed by thermoreceptors. These thermal receptors are specialized nerve endings that project perceived temperature stimuli via chemical processes onto nerve fibers in the spinal cord, from where the stimuli reach the hypothalamus.
The hypothalamus is the center of temperature regulation in the brain, where thermosensitive nerve cells receive the peripheral temperature information from the thermoreceptors and integrate it into the central information about the prevailing body temperature in order to initiate protective adaptations such as shivering or sweating.
The temperature sensation can be disturbed as a result of various neurological diseases, in particular with multiple sclerosis, polyneuropathies, strokes, borreliosis and dementia.
What is the temperature sensation?
The human temperature perception is also known as thermoception and relates to the perceived ambient temperature. Free nerve endings, so-called receptors, give the dermis and epidermis of the skin and the mucous membranes of the intestines a specific surface sensitivity to external stimuli. These external stimuli include touch stimuli, pain stimuli and temperature stimuli.
Medicine understands the epicritical sensitivity of the skin to be touch sensitivity through mechanoreceptors. Together with the pain receptors, on the other hand, the thermoreceptors are responsible for potopathic sensitivity.
Thermal and pain-related stimuli are absorbed by the receptors of the potopathic system and transmitted to fibers of the central nervous system. These nerve fibers or cord cells lie in the contralateral side of the posterior horn spinal cord, which extends over the anterior and lateral spinothalamic tract into the anterior cord tract. From the spinal cord, the perceived temperatures are finally passed on to the hypothalamus.
The perceived temperature differs from person to person and is never the same as the actual ambient temperature. This means that perceived temperatures are always subjective perceptions that are particularly related to the cultural origin and the overall physiological and psychological state of the person.
Function & task
The perception of temperature plays a role in particular for the protective reflexes and the body's heat regulation. The skin's receptors each have a specific sensitivity to irritation. Depending on this stimulus sensitivity, the receptors are differentiated into cold and warm receptors.
The cold receptors react to temperature ranges from 20 to 32 degrees Celsius, i.e. to temperatures below body temperature. They react to falling temperatures by increasing the discharge frequency. Warm receptors, on the other hand, are responsible for the range between 32 and 42 degrees Celsius and perceive temperature changes within this range.
The nerve endings generate certain action potentials depending on the temperature involved. Through chemical reactions, these action potentials are passed on via the synapses to the nerve fibers of the spinal cord, from where they are passed on to the thermosensitive nerve cells of the brain via neuronal switching points.
This is where the center of human thermoregulation lies in the hypothalamus. The body temperature is adapted to the outside temperature via this center. The thermoregulatory center of the brain compares the thermal information of the periphery with the central temperature information of the body.
On the basis of this comparison, the brain gives a thermoregulatory response and initiates, for example, heat losses through peripheral vasodilatation or sweating at hot temperatures. On the other hand, the response to the transmitted temperature stimuli can also correspond to a heat production or heat saving in the case of perceived cold, for example in the form of cold skin, increased metabolic activity or shivering.
The body prevents overheating and cooling down by responding to temperature perception. Human wellbeing is closely linked to the activity of thermoregulation, which in turn is closely related to blood circulation. Both heat stress and cold stress stress the blood circulation, as in both cases an adjustment of the body temperature must take place via changes in the blood flow.
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The sensation of temperature through the skin's warm and cold receptors can be disturbed or even absent as a result of various, mostly neurological phenomena. We are then talking about a sensitivity disorder. For example, polyneuropathies can damage nerve fibers in various locations. If sensitive nerve fibers, onto which the skin's thermoreceptors project, are damaged, then correspondingly disturbed temperature perceptions can arise.
Sensory disorders of the skin can, however, also be symptomatic of the autoimmune disease multiple sclerosis, in which there is permanent immunological inflammation in the central nervous system. In this case, an inflammation of the spinal cord areas for the transmission of thermal information can be responsible for a disturbed temperature sensation, as can an inflammation of the thermal center in the hypothalamus. However, the disturbed temperature sensation in multiple sclerosis is usually accompanied by general sensory disturbances such as persistent numbness.
Apart from that, diabetes can also be associated with a disturbed temperature sensation, especially in the area of the feet. Sensitivity disorders caused by diabetes are often accompanied by a loss of muscle reflexes and are usually limited to a sock-shaped area of the foot.
The list of diseases that can be related to incorrect temperature perception is long.In addition to the above, borreliosis, an incident on the sciatic nerve, dementia, a stroke or a migraine can also trigger the sensitivity disorder.
On the other hand, disturbed temperature sensation does not have to have a physical or pathological cause in all cases. For example, exhaustion can also confuse the perception of temperature. The same goes for mental stress and mental illness.
Disturbances in the perception of temperature are usually more worrying if they are restricted to a definable area of skin and do not affect the entire body. If the localization can be precisely defined, the impaired sensitivity is usually not related to exhaustion or psychological stress, but actually to a disease.
