Sensitivity: Function, Tasks, Role & Diseases

By sensitivity, medicine understands the perceptive ability of humans. This includes feeling and sensitivity.

What is sensitivity?

By sensitivity, medicine understands the perceptive ability of human beings. This includes feeling and sensitivity. Medical professionals refer to sensitivity as the ability to perceive various sensations. This ability primarily includes feeling. In addition, the term sensitivity is also commonly used for the basic sensitivity of the body’s mental and physical systems. If there is an increased sensitivity, it is called idiosyncrasy. The term sensitivity comes from the Latin word “sensibilis”. Translated, it means something like “connected with perception, sensation and senses” or “capable of sensation” when the term refers to humans. Since every human being is born with sentience, he or she is a fundamentally sensitive being. Ultimately, the psychological ability to feel depends on how the person perceives his environment and how his perceptual filters within the brain are developed. Highs and lows in life can also play a role.

Function and task

Sensitivity is a complex performance of the human nervous system. Sensory perceptions can be divided into quality and quantity. In higher centers of the central nervous system (CNS), they result in subjective sensations. Sensitivity is influenced by intraindividual and interindividual variations. This means that people perceive the same stimuli in different ways. According to physiological and anatomical aspects, sensitivity is divided into different ranges. However, there is sometimes considerable overlap. For example, the subdivision is based on the location of the stimulus origin. This includes the perception of external stimuli through skin and mucosa (see also exteroception) and the perception of internal stimuli (interoception). The latter perception can be subdivided into the perception of stimuli originating from the internal organs (visceroception) and the perception of movement and tension states of the musculoskeletal system (proprioception). Other criteria include the location of stimulus reception, such as surface and depth sensitivity, as well as the type of stimuli transmitted, such as the fine perception of touch, pressure and vibration (epicritic sensitivity) or the coarse perception of temperature and pain (protopathic sensitivity). Furthermore, a differentiation is made between the type of receptors such as thermoreception of cold and heat, mechanoreception of pressure, touch and strain, chemoreception of carbon dioxide partial pressure, oxygen partial pressure or pH, nociception of pain or direction of perception. This can in turn be divided into haptic and tactile perception. In haptic perception, an object is actively felt, while tactile perception involves the passive perception of touch. These roughly divided forms of sensibility can be attributed to leading anatomical structures as well as special physiological processes. Sensory stimuli are received by certain nerve endings, including Merkel cells, muscle spindles and Ruffini corpuscles. Via the nerves, the transmission of the stimuli takes place towards the posterior root of the spinal ganglion. From this location, the sensitive stimuli travel through the spinal cord to higher centers such as the cerebral cortex and thalamus. Various spinal cord tracts are responsible for transmitting the sensory stimuli from the external area to the central nervous system. These include the tractus spinocerebellaris anterior, the tractus spinocerebellaris posterior, the tractus spinothalamicus anterior, the tractus spinothalamicus lateralis, and the funiculus posterior.

Diseases and disorders

If pathological failures of sensibility occur, physicians speak of sensory disorders. This refers to neurological symptoms that cause partial or complete loss of sensibility. Sensitivity disorders can manifest themselves in very different ways. Thus, it is possible that the sensation of pain, touch, temperature, movement, vibration, position and force is impaired. The most common sensitivity disorders include qualitative changes.This term is used to refer to insensations such as an electrifying sensation, tingling, or furriness. The disorders usually appear in the supply areas of individual nerves or bluntly at the ends of the limbs. Responsible for this form of sensitivity disorders is mostly an overexcitability of nerve fibers or sensitive receptors. Qualitative changes are divided into dysesthesia and paresthesia. In dysesthesia, the affected person feels the perceptions as unpleasant. In paresthesia, unpleasant or even painful sensations occur without a specific triggering stimulus. Sensory perception may also be reduced or completely absent. In this case, patients no longer perceive any sensations in the affected areas. Total loss is referred to as anesthesia, which in turn can be subdivided into analgesia (abolition of pain sensitivity), thermanesthesia (abolition of temperature sensitivity), and pallanesthesia (loss of vibration perception). Disorders in which there is a weakening of sensitivity perception are called hypesthesia or decreased tactile perception. Subforms known are hypalgesia (reduction of pain perception), thermhypesthesia (reduced temperature sensitivity), or pallhypesthesia (reduction of vibration perception). In dissociated sensitivity disorder, there is an impairment of pain and temperature sensation in a specific area of the skin. In this case, the affected person perceives pain only as touch or pressure. However, it is also possible for sensitivity disorders to lead to increased perception. This includes, for example, allodynia. In this case, the affected person suffers from pain caused by stimuli that do not normally lead to pain. In hyperalgesia, there is an increased sensitivity to pain, so that even minor stimuli cause pain. In hyperpathia, the patient perceives touch stimuli as unpleasant. If there is increased sensitivity to touch, we are talking about hyperesthesia.