Somatosensory system. Tactile sensitivity

Tactile sensitivity (Latin tactilis - tangible, from tango - I touch)

a sensation that occurs when various mechanical stimuli act on the skin surface. Including - a type of touch (See Touch) ; depends on the type of impact: touch, pressure, vibration (rhythmic touch). Tactile stimuli are perceived by free nerve endings, nerve plexuses around hair follicles, and Pacinian corpuscles ( rice. 1 And 2 ), Meissner and Merkel discs (see Meissner corpuscles, Merkel cells), etc. Several Merkel discs or Meissner corpuscles can be innervated by one nerve fiber, forming a kind of tactile formation. Encapsulated Receptors (such as Pacinian and Meissner corpuscles) determine the threshold of T. h.: they are excited by touch and vibration and quickly adapt. The sensation of pressure occurs when slowly adapting receptors (such as free nerve endings) are stimulated. Compared to other skin sensations, tactile sensitivity quickly decreases with prolonged irritation, since in general adaptation processes in tactile receptors develop very quickly. The most differentiated T. occurs when the tips of the fingers, lips, and tongue are irritated, where a large number of different mechanoreceptor structures are located. The cortical part of the tactile analyzer a is represented in the postcentral and anterior ectosylvian gyri (see Organs of touch).

Lit.: Ilyinsky O. B., Physiology of skin sensitivity, in the book: Physiology of sensory systems, part 2, L., 1972 (Manual of Physiology); Esakov A. I., Dmitrieva T. M., Neuro-physiological foundations of tactile perception, M., 1971.

O. B. Ilinsky.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what “Tactile sensitivity” is in other dictionaries:

TACTIL SENSITIVITY- (English tactile sensitivity) a type of skin sensitivity that is associated with mechanical stimuli. Sensations of touch (see Tangoreceptors), pressure, and partially vibration (see Vibra ...) are associated with T. Great psychological encyclopedia

- (from lat. tactilis tangible, from tango I touch, I touch), a sensation that occurs when acting on the skin surface of decomposition. mechanical irritants; a type of touch. Tactile receptors are located on the surface of the skin and certain mucous membranes... ... Biological encyclopedic dictionary

TACTIL SENSITIVITY- (from lat. tactilis touch...) a type of skin sensitivity, which is associated with sensations of touch, pressure and partly vibration. A set of human organs (skin receptors, nerve pathways, corresponding centers in the cortex... ... Encyclopedic Dictionary of Psychology and Pedagogy

Tactile sensitivity- a type of touch that distinguishes the shape and size of an object, the nature of its surface, associated with the sensation of touching the object. Possible due to the presence of tactile exteroceptors. The largest number of tactile... ... Physical Anthropology. Illustrated explanatory dictionary.

TACTIL SENSITIVITY- [from lat. tactilis tactile] a type of touch; reflection in consciousness of certain mechanical properties of an object acting on the corresponding receptors of the skin surface as one of the types of irritations of touch, pressure,... ... Psychomotorics: dictionary-reference book

Tactile sensitivity- A type of skin sensitivity associated with sensations of touch, pressure and partly vibration... Adaptive physical culture. Concise encyclopedic dictionary- SENSITIVITY, the ability of animals and humans to perceive irritations from the external environment and from their own tissues and organs. In animals with a nervous system, specialized sensory cells (receptors) have a highly selective... ... Modern encyclopedia

Sensitivity is the body’s ability to perceive irritations emanating from the environment or from its own tissues and organs, and respond to them with differentiated forms of reactions. Types of sensitivity General sensitivity Superficial... ... Wikipedia

Skin receptors are responsible for our ability to sense touch, heat, cold and pain. Receptors are modified nerve endings that can be either free, unspecialized or encapsulated complex structures that are responsible for a certain type of sensitivity. Receptors perform a signaling role, so they are necessary for a person to interact effectively and safely with the external environment.

Main types of skin receptors and their functions

All types of receptors can be divided into three groups. The first group of receptors is responsible for tactile sensitivity. These include Pacinian, Meissner, Merkel and Ruffini corpuscles. The second group is
thermoreceptors: Krause flasks and free nerve endings. The third group includes pain receptors.

The palms and fingers are more sensitive to vibration: due to the large number of Pacinian receptors in these areas.

All types of receptors have different zones of sensitivity, depending on the function they perform.

Skin receptors:
. skin receptors responsible for tactile sensitivity;
. skin receptors that respond to temperature changes;
. nociceptors: skin receptors responsible for pain sensitivity.

Skin receptors responsible for tactile sensitivity

There are several types of receptors responsible for tactile sensations:
. Pacinian corpuscles are receptors that quickly adapt to pressure changes and have wide receptive fields. These receptors are located in the subcutaneous fat and are responsible for gross sensitivity;
. Meissner's corpuscles are located in the dermis and have narrow reception fields, which determines their perception of fine sensitivity;
. Merkel bodies - adapt slowly and have narrow receptor fields, and therefore their main function is the sensation of surface structure;
. Ruffini's corpuscles are responsible for sensations of constant pressure and are located mainly in the area of ​​​​the soles of the feet.

Also separately identified are receptors located inside the hair follicle, which signal the deviation of the hair from its original position.

Skin receptors that respond to temperature changes

According to some theories, there are different types of receptors for the perception of heat and cold. Krause flasks are responsible for the perception of cold, and free nerve endings are responsible for hot. Other theories of thermoreception claim that it is free nerve endings that are designed to sense temperature. In this case, thermal stimulation is analyzed by deep nerve fibers, and cold stimulation by superficial ones. Between themselves, temperature sensitivity receptors form a “mosaic” consisting of cold and heat spots.

Nociceptors: skin receptors responsible for pain sensitivity

At this stage, there is no final opinion regarding the presence or absence of pain receptors. Some theories are based on the fact that free nerve endings located in the skin are responsible for the perception of pain.

Prolonged and severe painful stimulation stimulates the emergence of a stream of outgoing impulses, and therefore adaptation to pain slows down.

Other theories deny the presence of separate nociceptors. It is assumed that tactile and temperature receptors have a certain threshold of irritation, above which pain occurs.

The somatosensory system includes the skin sensitivity system and the sensitive system of the musculoskeletal system, the main role in which belongs to proprioception.

1) Receiving information from receptors.

2) Processing information about various stimuli.

Mechanoreceptors

Nocireceptors

Thermoreceptors

Propriorectors

Rapidly adapting: hair follicle receptors, Pacinian corpuscles, Meissner corpuscles, Krause cones, Free n. endings of type Aδ.

Slowly adapting: Merkel discs, Taurus Rufini, free n. endings like C.

Hair follicle receptors

Location: in the inner layer of the skin, surrounding the hair follicle

Adaptation: fast. The discharge stops 50-500 ms after the stimulus is turned on

Reception: for movement, twitching of hairs, but not for the degree of their displacement

Innervation: one nerve fiber can serve several hundred follicles, and each follicle can be innervated by many receptors

Pacinian corpuscles (lamellar corpuscle, Vater-Pacini corpuscle)

Structure: has the structure of an onion or matryoshka doll. Enclosed in mucous membranes of connective tissue. Inside there is an elliptical nerve window.

Size: 0.5 – 0.7 mm in diameter and about 1-2 mm in length

Location: both in hairy and smooth skin, deep in the skin (in the adipose tissue of the subcutaneous layers, deeper than other solutions), little in the lips, fingertips

Reception: strong and sudden changes in pressure on the skin. They do not respond to constant pressure. Vibration: respond to vibration from 70 to 1000 Hz. However, the greatest sensitivity is at a vibration frequency of 200-400 Hz; in this case, they are able to respond to skin deformation of only 1 micron.

Pacinian corpuscles do not turn off during local anesthesia

Meissner's corpuscles

Located in the superficial layers of smooth skin (papillary dermis) and on the mucous membranes. Most of them are on the lips, palms, fingers, soles

They are analogues of hair follicle receptors for smooth skin.

Structure: oval-shaped connective tissue capsule (length 40-180 µm, width 30-60 µm)

The nerve endings form a spiral inside the capsule, the branches of which are isolated from each other by the membranes of Schwann cells.

The capsule is attached to the overlying layers of the epithelium by collagen fibers (which increases the mechanical connection between it and the surface of the skin)

Reception: responds to touch or pressure

Quickly adaptable. The discharge stops 50-500 ms after the stimulus is turned on

They respond to low-frequency vibration of 10-200 Hz, with a maximum frequency of 30 Hz.

Have small receptive fields

Krause cones (Terminal Krause flasks, Krause bulbs)

Location: smooth skin epidermis and mucous membranes. Only found in non-primate mammals (not in humans)

Structure: similar to Meissner's corpuscles. Lamellar capsule containing a spiral or rod-shaped nerve ending inside

Reception: For a long time it was believed that these were cold solutions, but this is not so. Krause flasks respond to low frequency vibration of 10-100 Hz.

Slowly adapting tactile receptors

1) Merkel discs

2) Ruffini Taurus

3) Free nerve endings (type C)

Illusion of sensory contrast

Merkel discs

Location: on areas of smooth skin they are located in small groups in the lowest layers of the epidermis, from where they are directed to the papillae of the dermis. In hairy areas they are located in special tactile discs (Pincus-Iggo bodies) - small elevations of the skin.

Structure: capsules with large, irregularly shaped nuclei and microvilli

Innervation: three tactile discs may have one nerve fiber, and inside the tactile discs, all Merkel discs (30-50 pcs) are served by the 1st nerve branch.

Reception: respond to touch or pressure. Stimulus – flexion of the epidermis under the action of a mechanical stimulus. Slowly adapt.r-ry. Continue to generate potentials even when pressure is maintained for a long time. They have small receptive fields.

Ruffini corpuscles (Ruffini cylinders, Ruffini endings)

Location: lower layer of dermis and mucous membrane

Reception: They were thought to respond to heat, but this is not the case. React to prolonged skin displacement and pressure.

Slowly adapt, continue to generate potentials even when pressure is maintained for a long time.

They have large receptor fields.

Free nerve endings

Location: in the epidermis and dermis, the most common solutions. Found in almost all areas of the skin.

Structure: do not have specialized detector cells. Type A delta (myelinated) or type C (unmyelinated) fibers extend from the endings.

Reception: excited by very weak, near-threshold stimulation. They react only to 1 gradation of stimulus (yes-no). Can detect weak mechanical stimuli, movement on the skin (crawling insect)

Adaptation: type A delta fibers... ?

Anterior spinothalamic tract - see photo

· The first neuron - axons in the dorsal roots enter the dorsal horn of the SPM, the body is in the SPM ganglion, the dendrite ends in mechanoreceptors of the skin

· The second neuron - axons move to the other side of the SPM and form the anterior spinothamic tract, body and dendrites in the cells of the gelatinous substance (posterior horn of the SPM)

· Third neuron - axons: part in the postcentral gyrus, part in the superior parietal lobule, body and dendrites in the posterior ventrolateral nuclei of the thalamus

Proprioception.

Proprioception is the perception of the posture and movement of our own body. Posture is determined by the angle of the bones at each joint, set either passively (by external forces) or actively (by muscle contraction). Their work combines signals from the vestibular organ, which makes it possible to determine the position of the body in the field of gravity. Proprioceptors are also involved in our conscious and unconscious motor activity. The afferent and efferent systems combine to create conscious proprioceptive sensations. If a sensation, for example, movement in a joint, persists after one of the components of the system is eliminated, it does not necessarily follow that it does not normally participate in the formation of this sensation. This corresponds to the principle of redundancy of the nervous system. Afferent information can be modulated at synapses by descending inhibition.
At the synapses through which the activity of afferents is transmitted to the central somatosensory neuron, it can change the magnitude of the receptive field of that neuron if afferents coming from the peripheral part of the receptive field are inhibited.

Types of proprioceptors

Mammals:

1) Muscle spindles

Mammalian muscle fibers

1) Extrafusal. Do all the work of muscle contraction

2) Intrafusal. They lack actin and myosin. They are designed to detect tension using solutions called muscle spindles

· Static. They react with constant muscle tension. Contraction force is detected

· Dynamic. They respond to on-off muscle stretching. Contraction speed is detected

2) Golgi tendon organs

IN tendons- part of the muscle, which is a connective tissue formation, through which the muscle is attached to the bone.

SOG – cluster-shaped sensory endings (2-3 mm in length and 1-1.5 mm in width). They are excited by muscle contraction due to tension in the tendons.

3) Joint receptors

In articular capsules: endings like Ruffini's corpuscles. Slow to adapt. Each has its own “excitation angle”

· In articular ligaments: endings like Golgi corpuscle and Pacinian corpuscle. They are activated when the joint moves to extreme positions or when its rotation is outside the normal range.

Nerve pathways

1) Cortical proprioceptive pathway– precisely localized conscious proprioceptive sensations

· Burdach's path

· Gaulle's path

His defeats:

1. Loss of sense of position and locomotion. With eyes closed, the patient cannot determine the position of his limbs

2. Astereognosis. With eyes closed, the patient can recognize and describe an object by touch.

2) Cerebellar pathways– unconscious coordination of movements

Flexing Path

Govers Way

Lesions of these pathways: movement coordination disorder. It becomes impossible to perform even the simplest movements without visual control without making gross mistakes. For example, touch the tip of your nose.

Body diagram

Body diagram– unconscious ideas about the position of one’s own body and its parts in space, about its boundaries and dynamic characteristics.

Properties of the body diagram (according to Haggard and Wolpert)

1) Spatial coding

3-dimensional spatial coordinates of the body and objects around it. The idea of ​​the boundaries of the body may not correspond to its real boundaries (tennis - the representation of the body as the end of a racket).

2) Modularity

The body diagram is not represented in any single region of the brain. Different parts of the body are in different areas of the cortex.

3) Adaptability

Ideas about one's own body diagram develop over the course of life.

Somatosensory plasticity

4) Updating while moving

After performing the movements, the body diagram changes according to the new body position

5) Interpersonality

St with mirror neurons.

6) Supramodality

Oliver Sacks. “The Man Who Fell Out of Bed” The body schema is not related to the primary sensory modality. It includes proprioception, vision, tactile information, etc. Sensory information is recoded into an abstract, supramodal form.

7) Coherence

When forming a body diagram, information from different senses is integrated.

Related information.

Human skin has tactile (tactile), temperature and pain receptors. Different types of receptors differ in their structure and are distributed in the skin in the form of a kind of mosaic.

Tactile receptors perceive mechanical stimulation, accompanied by a sense of touch and pressure. They have the shape of elongated bulbs, to which nerve endings approach. Tactile receptors include: tactile corpuscles (Meissner's corpuscles) having the appearance of one winding nerve ending, dressed in a capsule; lamellar corpuscles (Pacini corpuscles), consisting of a nerve ending surrounded by connective tissue plates; Merkel tactile discs located near the hair follicles, in the epidermis, as well as near the vessels and in the deep layers of the skin on the surface of the hand, in the palms of the hands, as well as on the tips of the fingers, lips, tendons, peritoneum and mesentery of the intestines, etc.. On average There are 25 tactile receptors per 1 cm2 of skin.

There are more receptors in the skin of the palms, at the ends of the fingers, on the lips and the tip of the tongue; least of all - in the skin of the back and abdomen. The threshold for irritation of the most sensitive areas is 50 mg, and in the least sensitive areas - up to 10 g. Based on their functional characteristics, tactile receptors are divided into phase and static. Phase tactile receptors are excited by dynamic stimulation, they have high sensitivity, a short latent period and quickly adapt. Static tactile receptors are excited mainly by static stimuli; they are less sensitive, but have a longer latent period and adapt more slowly.

The excitation that occurs in tactile receptors when the skin contacts objects enters the brain center of the tactile analyzer, localized in the area I of the somato-sensory zone of the cerebral cortex (posterior central twist of the cerebral cortex), where it is transformed into a sensation of touch or pressure. The differentiation of this sensation depends on the adaptive abilities of the tactile receptors of the skin: as stated above, phasic tactile receptors are easily adaptable and they respond only to changes in stimulus intensity and give a short-term sensation of touch, even if the pressure stimulus acts for a long time. Static tactile receptors adapt slowly and are excited only by prolonged exposure to a mechanical stimulus, which provides the sensation of pressure. By the mechanism of touch, irritation in the form of vibration can also be perceived. Thanks to tactile sensitivity, a person feels the shape, size and nature of the surface of surrounding objects. Contact is also characterized by spatial sensation, which consists in the ability to distinguish and perceive as separate, two simultaneously irritated points of the body.

Thermoreceptors, or temperature receptors, include two types of nerve endings. Some of them (Krause cones) perceive mainly cold stimuli, and the second (Ruffini corpuscles) perceive thermal stimuli. Thermoreceptors are located in the skin, as well as in the mucous membrane of the nose, mouth, larynx, esophagus, stomach and intestines. Structurally, thermoreceptors are glomeruli of thin nerve endings contained in connective tissue capsules. irritates the thermoreceptors of the skin and causes sensations of heat or cold in the cork part of the analyzer. As a result, the lumen of the blood vessels of the skin reflexively changes, due to which its blood supply and temperature change.

There are about 250 thousand cold receptors in the body, up to 30 thousand thermal receptors. Cold receptors are located at a depth of 0.17 mm, and thermal ones - 0.3 mm from the surface of the skin. Due to this, thermal receptors are excited relatively slowly, while cold receptors react very quickly, both to stimulation with a temperature below 18-20 ° C and to stimulation with a temperature above 40-45 ° C (for example, the “goose bumps” effect when immersing the body in hot water ). Thermoreceptors constantly inform the body about the state and changes in environmental temperature and are the most important link in maintaining body temperature (thermostasis). In children, the feeling of temperature manifests itself from the first days after birth.

Pain is a specific feeling, qualitatively different from any other feeling. It occurs when an irritant acts on one or another part of the body and is destructive. In this case, a whole series of defensive reactions arises aimed at preserving parts of the body or the whole organism.

Painful stimuli are perceived by pain receptors, or free nerve endings. Pain receptors are located not only in the skin, but also in muscles, bones, and internal organs. On the surface of 1 cm2 there are about 100 pain points, and on the entire surface of the skin there are about a million of them. There is almost no area on the skin where there are no pain receptors, but they are located unevenly: most in the armpit and groin areas and least on the soles, palms, and ears. Excitations arising in pain receptors as a result of the action of the stimulus are transmitted along the centripetal nerves to the higher cortical and subcortical (in the thalamus and hypothalamus) pain centers, where pain sensations are formed. The strength of pain largely depends on the state of the nervous system. Pain receptors respond to significant fluctuations in temperature, pressure, and the concentration of prostaglandins released by damaged body cells. The entry of information about the location and intensity of pain into the centers of the brain stimulates the release of endorphins into the blood, which are pain blockers.

When painful stimulation occurs, the normal functioning of the body is reflexively disrupted, and especially: the release of adrenaline into the blood increases, the concentration of sugar in the blood increases, the rhythm of heart contractions is disrupted, blood clotting accelerates, blood pressure increases, breathing is delayed, etc. With very strong painful stimuli, a painful shock can be observed (temporary loss of consciousness, dizziness, fainting).

Another type of skin sensitivity is the perception of tickling, which ensures that nerve endings are freely located in the superficial layers of the skin. This type of receptor is characterized by specific reactions to stimuli of varying intensities. The activation of this group of receptors is associated with the sensation of tickling, which gives the name to the receptors themselves - tickling receptors.

Due to the action of thermal factors, chemicals, electric current or ionizing radiation, damage to body tissues and, above all, skin, called burns, can occur. There are four degrees of burns based on the depth of tissue damage. First-degree burns are characterized by local (erythelium), slight swelling and an increase in local temperature, last 2-5 days and usually disappear without a trace. Second degree burns also cause local redness and swelling of the skin, and in addition, they are also characterized by the appearance of blisters filled with yellowish liquid (lymph). Such burns are accompanied by pain and fever.

III-A degree burns are accompanied by III-B degree burns with necrosis of all layers of the skin, and IV degree burns with necrosis of the skin and deep tissues. Emergency care for burns involves immediate removal and neutralization of the factor that caused it. In case of burns with a chemical substance, the affected skin and mucous membranes should be immediately rinsed with plenty of cold running water (for at least 15 minutes). If the skin is burned by sulfuric acid or quicklime, you should not rinse the affected area with water, as it will only enhance their effect. To do this, use butter or animal oil. In case of severe lesions, patients are hospitalized.

The tactile system provides sensations of pressure, touch, tickling and vibration.

The peripheral section of the tactile system is represented by various

different types of receptors. Receptors that perceive pressure are non-encapsulated nerve endings, Merkel discs, Ruffini bodies, end flasks of Krause; Meissner's corpuscles sense touch; the sensation of tickling is formed by stimulation of non-encapsulated nerve endings; The leading role in the perception of vibration is played by the Pacinian corpuscles, which have very rapid adaptation.

The conduction section (Fig. 16.15) begins with the dendrites of A-fibers and only from the tickle receptors - C-fibers of sensory neurons of the spinal ganglia and ganglia of the cranial nerves (the first neuron). In the dorsal horn of the spinal cord, the axons of the neurons of the spinal ganglia, without switching, as part of the posterior funiculi of the spinal cord ascend to the medulla oblongata, where they form a synapse with second neurons in the nuclei of the dorsal column. From the scalp and oral mucosa, impulses travel along the trigeminothalamic tract: to the second neurons located in the main nucleus of the trigeminal complex in the pons. Next, the pathway of the tactile system follows through the medial lemniscus to the nuclei of the thalamus optis (third neuron).

The cortical section is located in zones I and II of the somatosensory area of ​​the cerebral cortex (posterior central gyrus), where the fourth neuron is localized. From the projection zones of the cortex, tactile information enters the frontal and posterior association zones of the cortex, thanks to which the process of perception is completed.

Additionally:

Skin reception. Skin receptors. The receptor surface of the skin is huge (1.4 x 2.1 m2). The skin contains many receptors that are sensitive to touch, pressure, vibration, heat and cold, as well as painful stimuli. Their structure is very different (Fig. 14.19). They are localized at different depths of the skin and are distributed unevenly over its surface. Most of these receptors are found in the skin of the fingers, palms, soles, lips and genitals. In human skin with hair (90% of the entire skin surface), the main type of receptors are the free endings of nerve fibers running along small vessels, as well as more deeply localized branches of thin nerve fibers entwining the hair follicle. These endings make the hair highly sensitive to touch. Touch receptors are also tactile menisci (Merkel discs), formed in the lower part of the epidermis by contact of free nerve endings with modified epithelial structures. There are especially many of them in the skin of the fingers. In hairless skin, many tactile corpuscles (Meissner corpuscles) are found. They are localized in the papillary dermis of the fingers and toes, palms, soles, lips, tongue, genitals and nipples of the mammary glands. These bodies have a cone shape, a complex internal structure and are covered with a capsule. Other encapsulated nerve endings, but located more deeply, are the lamellar corpuscles, or Vater's Pacinian corpuscles (pressure and vibration receptors). They are also found in tendons, ligaments, and mesentery. In the connective tissue basis of the mucous membranes, under the epidermis and among the muscle fibers of the tongue there are encapsulated nerve endings of the bulbs (Krause flasks).

Theories of skin sensitivity. Numerous and largely contradictory. One of the most common is the idea of ​​the presence of specific receptors for 4 main types of skin sensitivity: tactile, thermal, cold and pain. According to this theory, the different nature of skin sensations is based on differences in the spatial and temporal distribution of impulses in afferent fibers excited by different types of skin stimulation. The results of studies of the electrical activity of single nerve endings and fibers indicate that many of them perceive only mechanical or temperature stimuli.

Mechanisms of excitation of skin receptors. A mechanical stimulus leads to deformation of the receptor membrane. As a result, the electrical resistance of the membrane decreases and its permeability to Na+ increases. An ionic current begins to flow through the receptor membrane, leading to the generation of a receptor potential. When the receptor potential increases to a critical level of depolarization, impulses are generated in the receptor, propagating along the fiber to the central nervous system.

Adaptation of skin receptors. Based on the speed of adaptation during prolonged exposure to a stimulus, most skin receptors are divided into rapidly and slowly adapting. The tactile receptors located in the hair follicles, as well as the lamellar bodies, adapt most quickly. The corpuscle capsule plays a major role in this: it accelerates the adaptation process (shortens the receptor potential), since it conducts fast changes well and dampens slow changes in pressure. Therefore, the lamellar body reacts to relatively high-frequency vibrations of 40 x 1000 Hz; Maximum sensitivity at 300 Hz. Adaptation of skin mechanoreceptors leads to the fact that we stop feeling the constant pressure of clothing or get used to wearing contact lenses on the cornea of ​​​​the eyes.

Properties of tactile perception. The sensation of touch and pressure on the skin is quite accurately localized, that is, a person relates to a specific area of ​​the skin surface. This localization is developed and consolidated in ontogenesis with the participation of vision and proprioception. Absolute tactile sensitivity varies significantly in different parts of the skin: from 50 mg to 10 g. Spatial discrimination on the skin surface, i.e., a person’s ability to separately perceive touch on two adjacent points of the skin, also differs greatly in different parts of the skin. On the mucous membrane of the tongue, the threshold of spatial difference is 0.5 mm, and on the skin of the back it is more than 60 mm. These differences are mainly due to the different sizes of cutaneous receptive fields (from 0.5 mm2 to 3 cm2) and the degree of their overlap.

Additionally: The activity of the tactile analyzer is associated with distinguishing various effects on the skin - touch, pressure.

Tactile receptors located on the surface of the skin and mucous membranes of the mouth and nose form the peripheral section of the analyzer. They become aroused when touched or pressed. The conductive section of the tactile analyzer is represented by sensitive nerve fibers coming from receptors in the spinal cord (through the dorsal roots and dorsal columns), medulla oblongata, visual thalamus and neurons of the reticular formation. The brain section of the analyzer is the posterior central gyrus. Tactile sensations arise in it.

Tactile receptors include tactile corpuscles (Meissner's), located in the vessels of the skin, and tactile menisci (Merkel's discs), which are found in large numbers on the tips of the fingers and lips. Pressure receptors include lamellar corpuscles (Pacini), which are concentrated in the deep layers of the skin, tendons, ligaments, peritoneum, and intestinal mesentery.

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Analytical and systematic approach to the study of body functions

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The concept of homeostasis and homeokinesis. Self-regulatory principles of maintaining the constancy of the internal environment of the body

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Basic principles and features of the propagation of excitation in the central nervous system

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Physiological mechanisms of reflex formation. Their structural and functional basis. Development of I.P. Pavlov’s ideas about the mechanisms of formation of temporary connections

The phenomenon of inhibition in VNI. Types of braking. Modern understanding of braking mechanisms

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The importance of blood circulation for the body. Blood circulation as a component of various functional systems that determine homeostasis

Heart, its hemodynamic function. Changes in pressure and blood volume in the cavities of the heart in different phases of the cardiac cycle. Systolic and minute blood volume

Physiological properties and characteristics of cardiac muscle tissue. Modern idea of ​​the substrate, nature and gradient of heart automation

Heart sounds and their origin

Self-regulation of heart activity. The Law of the Heart (Starling E.H.) and modern additions to it

Humoral regulation of heart activity

Reflex regulation of heart activity. Characteristics of the influence of parasympathetic and sympathetic nerve fibers and their mediators on the activity of the heart. Reflexogenic fields and their significance in the regulation of cardiac activity

Blood pressure, factors determining the value of arterial and venous blood pressure

Arterial and venous pulses, their origin. Analysis of sphygmogram and venogram

Capillary blood flow and its features. Microcirculation and its role in the mechanism of exchange of fluid and various substances between blood and tissues

Lymphatic system. Lymph formation, its mechanisms. Function of lymph and features of regulation of lymph formation and lymph flow

Functional features of the structure, function and regulation of blood vessels of the lungs, heart and other organs

Reflex regulation of vascular tone. Vasomotor center, its efferent influences. Afferent influences on the vasomotor center

Humoral influences on vascular tone

Blood pressure is one of the physiological constants of the body. Analysis of peripheral and central components of the functional system of self-regulation of blood pressure

Breathing, its main stages. The mechanism of external respiration. Biomechanism of inhalation and exhalation

Gas exchange in the lungs. Partial pressure of gases (O2, CO2) in the alveolar air and gas tension in the blood

Transport of oxygen by blood. Oxyhemoglobin dissociation curve, its characteristics. Blood oxygen capacity

Respiratory center (N.A. Mislavsky). Modern idea of ​​its structure and localization. Automation of the respiratory center

Reflex self-regulation of breathing. Mechanism of change of respiratory phases

Humoral regulation of respiration. The role of carbon dioxide. The mechanism of the first breath of a newborn baby

Breathing under conditions of high and low barometric pressure and when the gas environment changes

A functional system that ensures the constancy of the blood gas constant. Analysis of its central and peripheral components

Food motivation. Physiological basis of hunger and satiety

Digestion, its meaning. Functions of the digestive tract. Types of digestion depending on the origin and location of hydrolysis

Principles of regulation of the digestive system. The role of reflex, humoral and local regulatory mechanisms. Hormones of the gastrointestinal tract, their classification

Digestion in the oral cavity. Self-regulation of the chewing act. Composition and physiological role of saliva. Salivation and its regulation

Digestion in the stomach. Composition and properties of gastric juice. Regulation of gastric secretion. Phases of gastric juice separation

Types of gastric contractions. Neurohumoral regulation of gastric movements

Digestion in the duodenum. Exocrine activity of the pancreas. Composition and properties of pancreatic juice. Regulation and adaptive nature of pancreatic secretion to types of food and diets

The role of the liver in digestion. Regulation of bile formation and its secretion into the duodenum

Composition and properties of intestinal juice. Regulation of intestinal juice secretion

Cavity and membrane hydrolysis of nutrients in various parts of the small intestine. Motor activity of the small intestine and its regulation

Features of digestion in the large intestine

Absorption of substances in various parts of the digestive tract. Types and mechanism of absorption of substances through biological membranes

Plastic and energetic role of carbohydrates, fats and proteins...

Basal metabolism, the significance of its definition for the clinic

Energy balance of the body. Work exchange. Energy expenditure of the body during various types of labor

Physiological nutritional standards depending on age, type of work and body condition

Constancy of the temperature of the internal environment of the body as a necessary condition for the normal course of metabolic processes. A functional system that ensures the maintenance of a constant temperature in the internal environment of the body

Human body temperature and its daily fluctuations. Temperature of various areas of the skin and internal organs

Heat dissipation. Methods of heat transfer and their regulation

Excretion as one of the components of complex functional systems that ensure the constancy of the internal environment of the body. Excretory organs, their participation in maintaining the most important parameters of the internal environment

Bud. Formation of primary urine. Filter, its quantity and composition

Formation of final urine, its composition and properties. Characteristics of the process of reabsorption of various substances in the tubules and loop. Processes of secretion and excretion in the renal tubules

Regulation of kidney activity. The role of nervous and humoral factors

The process of urination and its regulation. Urine excretion

Excretory function of the skin, lungs and gastrointestinal tract

The formation and secretion of hormones, their transport in the blood, their effect on cells and tissues, metabolism and excretion. Self-regulatory mechanisms of neurohumoral relations and hormone-forming function in the body

Hormones of the pituitary gland, its functional connections with the hypothalamus and participation in the regulation of the activity of endocrine organs

Physiology of the thyroid and parathyroid glands

Endocrine function of the pancreas and its role in the regulation of metabolism

Physiology of the adrenal glands. The role of hormones of the cortex and medulla in the regulation of body functions

Sex glands. Male and female sex hormones and their physiological role in the formation of sex and regulation of reproductive processes. Endocrine function of the placenta

The role of the spinal cord in the processes of regulation of the activity of the musculoskeletal system and autonomic functions of the body. Characteristics of spinal animals. Principles of the spinal cord. Clinically important spinal reflexes

Medulla oblongata and pons, their participation in the processes of self-regulation of functions

Physiology of the midbrain, its reflex activity and participation in the processes of self-regulation of functions

Decerebrate rigidity and the mechanisms of its occurrence. The role of the midbrain and medulla oblongata in the regulation of muscle tone

Static and statokinetic reflexes (R. Magnus). Self-regulatory mechanisms for maintaining body balance

Physiology of the cerebellum, its influence on motor and autonomic functions of the body

Reticular formation of the brainstem and its descending influence on the reflex activity of the spinal cord. Ascending activating influences of the reticular formation of the brainstem on the cerebral cortex. Involvement of the reticular formation

Thalamus. Functional characteristics and features of nuclear groups of the thalamus. Hypothalamus. Characteristics of the main nuclear groups. Participation of the hypothalamus in the regulation of autonomic functions and in the formation of emotions and motivations

Limbic system of the brain. Its role in the formation of biological motivations and emotions

The role of the basal ganglia in the formation of muscle tone and complex motor acts

Modern idea of ​​the localization of functions in the cerebral cortex. Dynamic Function Localization

Teachings of I.P. Pavlov about analyzers

Receptor department of analyzers. Classification, functional properties and characteristics of receptors. Functional mobility (P.G. Snyakin). Conductor department of analyzers. Features of afferent excitations

Adaptation of analyzers, its peripheral and central mechanisms

Characteristics of the visual analyzer. Receptor apparatus. Color perception. Physiological mechanisms of eye accommodation

Hearing analyzer. Sound-collecting and sound-conducting devices. Receptor section of the auditory analyzer. The mechanism of the occurrence of receptor potential in the hair cells of the spiral organ

The role of the vestibular analyzer in the perception and assessment of the position of the body in space and during its movement

Motor analyzer, its role in the perception and assessment of body position in space and the formation of movements

Tactile analyzer. Classification of tactile receptors, features of their structure and functions

The role of the temperature analyzer in the perception of the external and internal environment of the body

Physiological characteristics of the olfactory analyzer. Classification of odors, mechanism of their perception

Physiological characteristics of the taste analyzer. The mechanism of receptor potential generation under the influence of taste stimuli of different modalities

The role of the interoceptive analyzer in maintaining the constancy of the internal environment of the body, its structure. Classification of interoceptors, features of their functioning Determination of pressure in the pleural cavity

Methods for determining the vital capacity of the lungs. Spirometry, spirography. Pneumography, pneumotachometry

Determination and comparison of the gas composition of inhaled and exhaled alveolar air

Oxygemometry and oxygemography

Methods for studying salivation in animals (I.P. Pavlov, D.D. Glinsky). Methods for studying the activity of the salivary glands in humans. Masticocyography

Chronic methods for studying the secretory function of gastric glands in animals

Cardiology of the heart. Questions and answers for the exam

Features of organizing and conducting recreational and health activities

Final qualifying work. Recreation and sports and health tourism. Characteristics of various types of recreational activities. Purpose, objectives, methods and organization of the study. State and prospects for the development of park areas in Moscow. Features of organizing and conducting recreational and health activities.

Internet page of the department with hypermedia content markup

Faculty of Informatics Department of Applied Informatics Discipline: Intelligent Systems Laboratory work on the topic: “Internet page of the department with hypermedia content markup”

Human Anatomy and Physiology

General functions of the hypothalamus. Functional anatomy of the hypothalamus. Hypothalamus and the cardiovascular system. Hypothalamus and behavior. Principles of organization, Functional disorders in people with damage to the hypothalamus. The structure and location of the epiphysis. Pineal gland hormones

The problem of demarcation of scientific knowledge

The problem of finding a criterion by which one could separate scientific theories from non-scientific assumptions and statements, metaphysics, and formal sciences (logic, mathematics). Early periods. Positivism. The principle of verifiability. The principle of falsifiability.