Sensitivity (we consider the concept in the framework of physiology) is one of the most important properties that both a person and any other living organism possess. Therefore, it requires detailed consideration. In the article, we will present the types of sensitivity according to a number of classifications, as well as the types of its violations.
What is this?
All types of sensitivity in physiology are:
- Part of the reception perceived by the psyche. Reception - afferent impulses entering the departments of the central nervous system.
- The ability of a living organism to perceive various irritations that come from both its own organs and tissues, and from the environment.
- Ability of the body preceding a differentiated response to a stimulus - reactivity.
And now - the classification of types of sensitivity.
Total Sensitivity
Several groups stand out here at once - let's present their contents separately.
Exteroceptive type (superficial sensitivity)internally divided into:
- tactile (rough);
- pain;
- temperature (cold and heat).
Proprioceptive type (deep sensitivity) - a sense of being in space, the position of your body, limbs relative to each other. This view has the following categories inside it:
- sense of own body weight, pressure;
- vibrating;
- feeling of touch (tactile light);
- articular-muscular;
- kinesthesia
Complex types of sensitivity:
- The feeling is two-dimensional-spatial - with its help we determine the place of touch to our body. It helps to find out what symbol, number or letter is "written" on the skin with the finger of another person.
- Interoceptive - this sensitivity is caused by irritation of internal organs.
- Discriminatory - helps to distinguish between touches, skin injections that are applied at a close distance to each other.
- Stereognost - this kind of sensitivity helps to recognize this or that object by touch.
As for the above examples, their identification will be possible only with further receipt and processing of the impulse from the primary cortical layer of the analyzer (it will be the central posterior gyrus) into associative or secondary cortical fields. The latter are predominantly located in the parieto-postcentral zones, in the lower and upper parietal lobes.
Go to the next classification.
Total andspecial sensitivity
The same concepts are used here, only for a slightly different classification.
General sensitivity is divided into simple and complex.
Special sensitivity is represented by the following categories:
- visual;
- tasty;
- olfactory;
- auditory.
Difficult sensitivity
In this classification, we will consider different types of sensitivity - characteristic not only for humans, but for all living beings in general.
This is the following:
- Vision is the body's perception of light.
- Echolocation, hearing - the perception of sounds by living systems.
- Smell, taste, stereochemical sense (typical of insects and hammerhead sharks) - chemical sensitivity of the body.
- Magnitoreception - the ability of a living being to feel the magnetic field, which allows you to navigate the terrain, determine the height, plan the movement of your own body. Some sharks have a type of sensitivity.
- Electroreception - the ability to sense the electrical signals of the surrounding world. Used to search for prey, orientation, various forms of biocommunication.
According to phylogenetic criteria of formation
Classification was proposed by the scientist G. Head. There are two kinds of sensitivity of a human being, a living being:
- Protopathic. A primitive form that has its center in the thalamus. Notcan give an accurate definition of the localization of the source of irritation - neither external nor inside one's own body. It no longer reflects objective states, but subjective processes. Protopathic sensitivity ensures the perception of the strongest, coarsest forms of stimuli, pain and temperature, which are dangerous to the body.
- Epicritical. Has a cortical center, is more differentiated, objectified. Phylogenetically considered younger than the first. Allows the body to perceive more subtle stimuli, assess their degree, quality, localization, nature, etc.
By location of receptors
This classification was proposed in 1906 by the English physiologist C. Sherrington. He suggested dividing all sensitivity into three categories:
- Exteroceptive. Here information is perceived by the body with the help of the so-called exteroceptors, which are located in the mucous membranes and skin. These are temperature, pain, tactile forms of sensitivity.
- Proprioceptive. In this case, information is perceived by proprioceptors. They are found in tendons, muscles, labyrinth, joints, semicircular canals.
- Interoceptive. Here, irritation will be perceived by interceptors (otherwise they are called visceroceptors). They are found in blood vessels, internal organs, and so on.
Varieties of skin sensitivity
Classical physiology distinguishes the following types of skinsensitivity:
- Pain. Occurs under the influence of stimuli that are destructive in their strength and nature. She will talk about a direct danger to the body.
- Thermal (temperature) sensitivity. It allows us to determine hot, warm, cold, icy. Its greatest importance is for the reflex regulation of the body.
- Touch and pressure. These feelings are connected. Pressure, in fact, is a strong touch, so there are no special receptors for it. Experience (with the participation of vision, muscle feeling) allows you to accurately localize the area affected by the stimulus.
In some classifications, the varieties of skin sensitivity will be divided as follows:
- Pain.
- Feeling cold.
- Touch.
- Feeling warm.
Types of sensation thresholds
Now consider the classification of types of sensitivity thresholds:
- The absolute lower threshold of sensation. This is the smallest strength or magnitude of the stimulus, at which its ability to cause nervous excitation in the analyzer is sufficient for the occurrence of one or another sensation.
- The absolute upper threshold of sensation. On the contrary, the maximum value, the strength of the stimulus, beyond which the body already ceases to perceive it.
- Discrimination threshold (or differential sensation threshold) - the smallest difference in the intensity of two identical stimuli that a living organism can feel. Notethat not every difference will be felt here. It needs to reach a certain size or strength.
Varieties of Disorders
And now - the types of sensitivity disorders. The following stands out here:
- Anesthesia is the name given to the complete loss of any type of sensation. There is thermal (thermoanesthesia), tactile, pain (analgesia). There may be a loss of a sense of stereognosis, localization.
- Hypesthesia - this is the name of a decrease in sensitivity, a decrease in the intensity of certain sensations.
- Hyperesthesia is the opposite of the previous phenomenon. Here the patient has an increased sensitivity to certain stimuli.
- Hyperpathy - cases of perversion of sensitivity. The quality of sensation changes - point irritations crumble, some qualitative differences between the stimuli in the patient are erased. The sensation is painted in painful tones, it can be purely unpleasant. The aftereffect is also diagnosed - the sensation continues to remain after the stimulus has ceased.
- Paresthesia - a person experiences any sensations without the presence of their stimuli. For example, "goosebumps", a sharp sensation - "as if thrown into a fever", burning, tingling, etc.
- Polyesthesia - with such a violation, a single sensation will be perceived by the patient as multiple.
- Dysesthesia is a perverted perception of a certain irritation. For example, touch feels like a blow, cold feels likeheat.
- Synesthesia - a person will perceive the stimulus not only in the location of its direct impact, but also in a different zone.
- Allocheiriya - a violation, something related to the previous one. The difference is that a person feels the impact of the stimulus not in the location of its impact, but in a symmetrical area of the opposite part of the body.
- Thermalgia - cold, heat are painfully perceived by the patient.
- Dissociated sensory disorder - a case in which a certain sensation is disturbed, but all others are preserved.
Types of disorders
Types of sensory impairment can be divided into the following categories:
- Cork type. This is a sensory disorder that will be seen on the opposite side of the body.
- Conductor type. Defeat of the conducting ways of sensitivity. Disorders will be found downstream of the location of the given lesion.
- Dissociated (segmental). It will be observed in case of damage to the sensitive nuclei of the cranial nerve of the brain stems, as well as in case of damage to the sensitive apparatus related to the spinal cord.
- Distal (polyneuric) type. Multiple lesions affecting peripheral nerves.
- Peripheral type. It is characterized by damage to the peripheral nerves and their plexuses. There is a disorder of all kinds of sensations here.
Sensitivity is a fairly broad phenomenon in understanding. Evidence of this is the large numberclassifications that internally subdivide it into multiple groups. Also today, a variety of types of sensitivity disorders have been established, the gradation of which is associated with the localization of the lesion, the manifestation of sensations in the patient.
