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Sensitivity

Sensitivity - the body's ability to perceive irritation emanating from the environment or from its own organs and tissues. In physiology, the entire totality of afferent systems is united by the concept of reception. Sensitivity is a special case of reception, when afferent impulses lead to the formation of sensations. Not everything that undergoes reception is felt. For example: the Govers and Flexig afferent pathways to the cerebellum do not reach the cortex, the proprioreceptive impulses conducted along these pathways are not felt, although they cause responses to muscles due to the automatism of the cerebellar system.

Environmental irritants are perceived by a person with the help of specific functional systems - analyzers.

Analyzers are functional associations of peripheral and central nervous system structures that perceive and analyze information about the phenomena of the external and internal environment. I.P. Pavlov structurally divided the analyzer into three main departments:

16. Receptor formations that perceive and transform specific irritations (peripheral section).

17. A conduction system with switching neurons transmitting a centripetal impulse (conductive section).

18. The cortical end of the analyzer, in which the higher analysis and synthesis of the resulting excitations takes place (cortical department).

Receptors (and in accordance with them sensitivity) are divided into general and special (associated with the sensory organs). The first, in turn, are divided into:

• Exteroreceptors - pain, temperature (Krause bulbs, Ruffini bodies), tactile (Fater-Pacini bodies, Meissner, Merkel, Golgi-Mazzoni bodies).

• Proprioreceptors - located in the muscles, tendons, ligaments, joints.

• Interoreceptors - baro- and chemoreceptors located in the internal organs.

Pathways of deep and superficial sensitivity.

A) Conductors of pain and temperature sensitivity.

The first neuron is located (as in other tracts of general sensitivity) in the spinal ganglia and is represented by a pseudo-unipolar neuron. The peripheral process in the composition of the spinal nerve, plexus, peripheral nerve goes to the receptors of the corresponding dermatome. Axons form the spinal nerve and the posterior root. Entering the substance of the spinal cord, these fibers pass through the marginal zone, the gelatinous substance and form a synapse with the second neuron at the base of the horn. The cells of the second neuron make up the so-called native nuclei - a column of nerve cells that runs along the spinal cord (Clark's pillar). Even before the synapse, the axon of the first neuron gives up the collateral for the arc of the corresponding segmental reflex. The axon of the second neuron goes obliquely and upward and 1–2 segments higher in the region of the anterior commissure passes to the opposite side. Entering the lateral cord of the opposite side, the axon of the second neuron is directed upward along with similar fibers that have entered the lateral cord below. A bundle is formed that passes through the entire spinal cord and brain stem. In the bridge and midbrain, it adjoins the lemniscus medialis from the dorsal side and ends in the ventrolateral nucleus of the thalamus. At the place of beginning and end, this path was called the Spino-Thalamic. Axons of the third neuron (thalamic) through the posterior third of the posterior leg of the inner capsule as part of the thalamo-cortical pathway are sent to the postcentral gyrus and superior parietal lobe.

Fibers of the lateral spinal thalamic pathway are distributed very peculiarly. From the dermatomes located below (for example, legs), the fibers lie outside, and from those located higher (arms) inside. This pattern of arrangement of long conductors, or the law of the eccentric arrangement of long conductors (Auerbach-Flattau law), is important for topical diagnostics.
In an extramedullary tumor, the area of ​​superficial sensitivity disorder begins with the distal parts of the leg, and with further growth it spreads upward (an ascending type of sensitivity disorder). With an intramedullary tumor, the zone of sensitivity disorders, on the contrary, spreads from top to bottom (descending type).



B) Conductors of deep and tactile sensitivity.

The first neuron of this pathway, like other types of general sensitivity, is represented by a cell of the spinal ganglion. Axon enters the posterior cord of his side, giving up a branch to form an arc of a segmental reflex, then rises up to the medulla oblongata. The combination of these ascending fibers forms thin and wedge-shaped bundles (Gaulle and Burdach bundles). In the course of the fibers of the posterior cords, there is the following feature - the newly arrived fibers lie outside of the existing ones. Therefore, fibers from the lower limb pass in the medially located thin bundle, and in the lateral wedge-shaped from the trunk and arm.

The axons of the first neurons at the level of the caudal regions of the medulla oblongata terminate in the nuclei of the same name. Here are the bodies of the second neurons. Their axons go to the opposite side and take an upward direction, in the bridge of the brain they are joined by fibers of pain and temperature sensitivity. This path has two names: bulbo-thalamic or, according to the old nomenclature, the medial loop. The third neuron of this pathway is located in the thalamus, its axon through the posterior third of the posterior leg of the inner capsule goes to the postcentral gyrus and the superior parietal lobe.

Sensory Disorders.

A) Types of disorders of sensitivity.

Anesthesia is the loss of one kind or another of sensitivity. There are tactile, thermal anesthesia (thermoanesthesia), pain (analgesia);

Hypesthesia is not a complete loss, but only a decrease in sensitivity, a decrease in the intensity of sensations. It can relate to all sensitivity, as well as its individual types;

Hyperesthesia - hypersensitivity;

Hyperpathy - characterized by an increase in the threshold of perception. The patient does not feel single injections, but a series of injections (5-6 or more) causes intense and painful pain, which arises after a certain hidden period, as if suddenly. The patient cannot indicate the location of the injection. Single irritations are perceived as multiple, the zone of these sensations expands. Perception of sensations remains after the termination of the application of irritation (aftereffect);

Dysesthesia is a perversion of the perception of irritation: a touch is perceived as pain, cold as heat;

Polyesthesia - a single irritation is perceived as multiple.

Synesthesia - a sensation of irritation not only at the site of application, but also in some other area;

Alloheiria - the patient's irritation is not localized where it was applied, but on the opposite side of the body, usually on a symmetrical site.

Sensitive phenomena that occur without the application of external stimuli, such as pain and paresthesia, differ from the types of sensitivity disorders identified during the examination considered above.

Paresthesia - pathological sensations experienced without irritation from the outside can be extremely diverse: creeping crawls, heat or cold, tingling, burning.

Pain is a real subjective sensation caused by an applied (too intense) irritation or pathological process in the body. The pains are local, projective, radiating and reflected.
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Sensitivity

  1. Sensitivity and types of sensory impairment
    Sensitivity is the body's ability to perceive irritations emanating from the environment or from its own tissues and organs. The analyzer consists of three departments: the receptor, the conductor, and the cortical. Receptors are the terminal formations of sensitive nerve fibers that perceive changes in the body or outside it and transmit it in the form of impulses.
  2. RESTORE SENSITIVITY
    When reading this section, one should take into account the fact that we are talking about the possibility of restoration of sensitivity, and not about its normalization. With anatomical damage to the spinal cord, restoration of sensitivity proceeds in a certain sequence. The first to restore surface skin sensitivity. The gradually appearing foci of skin sensitivity expand and
  3. Sensitivity
    The primary perception of all stimuli in the human body is carried out by receptors - specific cells that perceive the effects of the external and changes in the internal environment of the body. Receptors-Exteroreceptors Proprioreceptors Interoreceptors General features of the three-neuronal paths of surface and deep sensitivity • The first neuron is located in the intervertebral node.
  4. SENSITIVITY STUDY
    In the study of sensitivity, they are based on the testimony of patients in response to certain stimuli. However, the study of sensitivity in children presents great difficulties, since a child cannot always clearly differentiate irritation, correctly analyze his feelings and adequately describe them. In young children, often have to be limited to research only
  5. SENSITIVITY STUDY
    In the study of sensitivity, they are based on the testimony of patients in response to certain stimuli. However, the study of sensitivity in children presents great difficulties, since a child cannot always clearly differentiate irritation, correctly analyze his feelings and adequately describe them. In young children, often have to be limited to research only
  6. SENSITIVITY VIOLATION
    Pain syndrome occurred in 87 patients (100%). Local soreness in the area of ​​trauma and pain symptoms accompanying spastic convulsive events were noted in 87 patients (100%); phantom pains - in 13 patients (14.9%); radicular pain - in 87 patients (100%); causalgia was observed in 17 patients (19.5%). In addition to pain, a violation of all types of sensitivity was observed below
  7. SENSITIVITY VIOLATION
    In the clinic, it is customary to distinguish between types and types of sensitive disorders. The following types of sensory impairment exist, which are distinguished depending on a qualitative or quantitative change in sensations. Anesthesia - the complete loss of any kind of sensitivity - is due to the fact that, due to some obstacles, the pulses do not reach the corresponding cortical paths
  8. Sensitivity and its disorders
    Sensitivity is the body's ability to perceive irritations emanating from the environment or from its own tissues and organs. Teaching I.P. Pavlova on analyzers laid the foundation for a natural understanding of the nature and mechanisms of sensitivity. Each analyzer consists of a peripheral (receptor) department, a conductor part and a cortical department. Receptors - Special
  9. Hearing sensitivity
    Our auditory organ is very sensitive. With normal hearing, we are able to distinguish sounds that cause negligible (calculated in fractions of a micron) vibrations of the eardrum. The sensitivity of the auditory analyzer to sounds of different heights is not the same. The human ear is most sensitive to sounds with a frequency of oscillation from 1000 to 3000. As you decrease or
  10. SENSITIVITY TYPES
    The nervous system developed during the body’s interaction with the environment. This process is dynamic, the nervous system changes and is constantly improved in phylogenesis and ontogenesis. When signals from the external and internal environment arrive, the nervous system provides supportive reactions and maintains homeostasis. A complex of afferent systems that receives information at
  11. PARTICULAR SYMPTOMATOLOGY OF SENSITIVITY DISORDERS
    Damage to the trunk of the peripheral nerve causes a violation of all types of sensitivity in the area of ​​its innervation, i.e., according to the peripheral mononeuric type. This is because nerve fibers pass through the nerve trunk for various types of sensitivities. The defeat of individual nerve fibers can be more or less deep, which leads to unequal violation of certain types
  12. SENSITIVITY STUDY METHODOLOGY
    Tactile (tactile) sensitivity, with which a person recognizes tangential irritations, is examined, suggesting the researcher with closed eyes to record each irritation applied to various parts of the body surface in the form of touches with a thin paper or a piece of cotton wool. The study of pain sensitivity is to recognize the irritation caused by the tip
  13. Polyneuritic type of sensitivity disorder
    The zone and nature of sensory impairment detected in a patient can help to resolve the issue of localization of his pathological focus. Topical diagnosis will undoubtedly become more reliable if, at the same time, information about other changes in the neurological status associated with sensitivity disorders is taken into account. With the defeat of various levels of the system
  14. Cortical Type Disorder
    (Internet) Sensitivity - the body's ability to perceive irritation emanating from the environment or from its own organs and tissues. In physiology, the entire totality of afferent systems is united by the concept of reception. Sensitivity is a special case of reception, when afferent impulses lead to the formation of sensations. Not everything that undergoes reception is felt. For example:
  15. Sensitivity
    Under the sensitivity refers to the ability to the elementary form of mental reflection - sensation. Unlike irritability, the concept of “Ch.” Uses the criterion of signaling: Ch. - reflection by the body of such influences that are not directly biologically significant (eg, due to their energy weakness), but can signal the presence (change) of other conditions environment
  16. PARTICULAR SYMPTOMATOLOGY OF SENSITIVITY DISORDERS
    Damage to the trunk of the peripheral nerve causes a violation of all types of sensitivity in the area of ​​its innervation, i.e., according to the peripheral mononeuric type. The defeat of the nerve plexus (cervical, brachial, lumbar, sacral) causes sensitive, motor and autonomic disorders in the area innervated by the nerves, combined with pain and paresthesias and relate to
  17. SENSITIVITY SYNDROMES AND SENSITIVITY FUNCTIONS
    Three main types of sensitivity disorders are distinguished depending on the distribution borders: peripheral - in the area of ​​nerve innervation, segmental - in the area of ​​innervation of the segment of the spinal cord, posterior (sensitive) root or intervertebral ganglion, conductor - below the level of damage to the conductors of sensitivity in the spinal cord or brain. Depending on the level of lesions
  18. Adenosine Sensitive VT
    Adenosine does not directly affect the ventricular contractile fibers and Purkinje fibers, however, it counteracts the positive inotropic and electrophysiological effects of catecholamines on these structures. B. Lerman et al. (1986) reported cases of VT, sensitive to adenosine. In 4 patients (3 men and 1 woman; age - 25 to 32 years) without signs of heart disease
  19. Level of undifferentiated sensitivity
    The lowest, germinal level of development of the mental, corresponding, according to A.N. Leont'ev, undifferentiated sensitivity, follows immediately the dopsychic form of life and the dopsychic form of reflection. Accordingly, the phase of background activity (always responding, as shown in Section 3 of Chapter 1, to the previous level of development) is carried out here at the pre-mental level and
  20. Syndromes of impaired sensory and sensory functions
    Three main types of sensitivity disorders are distinguished depending on the distribution borders: peripheral - in the area of ​​nerve innervation, segmental - in the area of ​​innervation of the segment of the spinal cord, posterior (sensitive) root or intervertebral ganglion, conductor - below the level of damage to the conductors of sensitivity in the spinal cord or brain. Depending on the level of lesions
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