The meaning and principle of the analyzers and sense organs

All life on Earth needs information about the environment in which living organisms live, and man is no exception. The possibility of obtaining information about the environment provides sensitive (sensory) systems. Any activity of the sensory system begins with the receptor perception of the energy of the stimulus and its transformation into nerve impulses, as well as the transfer of these impulses through the neural circuit to the brain, which transforms the nerve impulses into specific sensations, for example, auditory, olfactory, visual, tactile, and others.

What are analyzers and sense organs of a person? About this further.

About analyzers

During the study of the physiology of sensory systems, Academician Pavlov IP Created a work on analyzers. Each analyzer has three departments: central, peripheral and conductor.

The peripheral section represents receptors - nerve endings, which have a sensitivity selective only to a certain kind of stimuli. They are included in the sense organs corresponding to them.

Analyzers and sense organs: their structure and functions

The analyzer has a typical structure. It consists of the receptor department, the conducting part and the central department. The receptor or peripheral part of the analyzer can be represented as a receptor. He perceives and performs the primary processing of certain information. For example, a sound wave is picked up by an ear curl, light by an eye, pressure by the skin receptors.

In complex sensory organs (taste, sight, hearing), in addition to receptors, there are auxiliary structures that provide good perception of the stimulus and perform basic, protective and other functions. For example, the auxiliary structures of the visual analyzer are represented by the eyes, while the visual receptors are only sensitive cells (cones and rods). External receptors can be identified, which are located on the surface of the body and perceive irritations of the external environment, and internal, perceiving irritations of the internal environment and organs of the body.

How are analyzers and sense organs arranged?

The analyzer conductor section is shown by nerve fibers that conduct nerve impulses into the central nervous system from the receptor (auditory, olfactory, optic nerve and others).

The central part of the analyzer is a specific area of the cerebral cortex in which the sensory information is synthesized and analyzed and its transformation into specific sensations (olfactory, visual, and others).

An indispensable condition for the normal operation of the analyzer can be called the integrity of all three of its departments. How do the sensory organs and analyzers work? About this below.

The work of the visual analyzer

The receptor part of this structure is represented by the eyes. Chemical reactions here form an electrical impulse that passes through the optic nerve and is projected into the occipital lobe of the cerebral cortex.

Work of the auditory analyzer. The receptor here is the ear. The external part of it is going to sound, the middle is supplied further. The signal moves along the auditory nerve to the brain, its temporal lobes.

The work of the olfactory analyzer. The olfactory epithelium covers the inner shell of the nose. They perceive the molecules of the smell, while creating nerve impulses.

Work of taste analyzers. They are represented by taste buds - sensitive chemical receptors that react to chemicals.

There are also tactile, temperature, pain analyzers - also consist of receptors on skin integuments. Let's consider in more details concepts "sense organs" and "analyzers".

Body of sight

The largest amount of information about the external world to a person is transmitted through the organ of vision, that is, the eye, which consists of an auxiliary apparatus and an eyeball. There is an eyeball in the facial part of the skull in the deepening of the eye socket, it is protected by the upper and lower eyelid from mechanical damage, as well as the eyelashes and protrusions of the frontal, nasal and malar skull bones.

Analyzers and human senses are unique.

In the corner of the orbits the upper lobe is the lacrimal gland, which secrete a lacrimal fluid, a tear that facilitates the movement of the eyelids, which moistens the surface of the eyeball. In the inner corner, an excess of tears accumulates, enters the tear ducts, and then into the nasal cavity along the nasolacrimal duct. Six oculomotor muscles connect the eyeball and the orbital walls of the orbit and allow movement down, up, to the sides.

Three shells form the walls of the eyeball: fibrous (external), vascular (medium) and retina or mesh (internal). The outer shell in the larger, posterior part forms a sclera (a dense white envelope), and in front passes into a transparent membrane, permeable to light, the cornea. The core of the eye protects the sclera, and also preserves its shape. The eye nourishes the blood vessels, which are rich in the choroid. The iris, that is, its anterior part, is pigmented, and this pigment determines the color that the eye has. So are the analyzers and sense organs.

The anterior chamber of the eye

The anterior chamber of the eye is the space between the iris and the cornea, filled with a viscous liquid. Behind the iris is a biconvex lens 10 mm in diameter - an elastic and transparent crystalline lens. It is attached to the ciliary muscle, which is located in the choroid. If the tension of the ligaments decreases, that is, the ciliary muscle relaxes, the lens becomes more convex due to its elasticity and elasticity, and vice versa, the lens becomes thicker when the ligament tension is increased.

The posterior chamber of the eye is filled with liquid and is located between the lens and the iris. Behind the lens the cavity of the eyeball is filled with a transparent gelatinous mass, the so-called vitreous body, which is intended to retain the shape of the eyeball, to give it firmness and, in addition, to keep in contact with the sclera and the vascular membrane of the mesh shell. This is the basic principle of the work of the sense organs and analyzers.

Retina

The retina, or mesh inner shell, is the most complex structure. It lays the wall of the eyeball from the inside. It is formed by the nerve endings of the optic nerve, receptor (light-sensitive) cells (cones and rods) and pigment cells, which are located in the outer layer of the mesh shell. A black spot traces the pigment layer through the pupil hole. This is how the sensory organs and analyzers act.

The eye is considered an optical apparatus. Its light refractive system includes: vitreous, lens, watery back and anterior chamber fluid, cornea. Each element of the optical system transmits through itself light rays refracted, falling on the retina and forming an inverted and reduced image of objects visible to the eye.

With what analyzers are connected sensory organs, now it became clear.

The mechanism of light perception

The mesh shell contains about 130 million rods and 7 million cones. In the cones there is pigment iodopsin, which allows you to perceive colors in daylight. They can also be divided into three types, which have a spectral sensitivity to blue, red and green colors.

In sticks and cones (photosensitive receptors) under the influence of light rays, photochemical complex reactions occur, which are accompanied by the splitting of the pigment visual into the compound. This photochemical reaction promotes the appearance of excitation transmitted through the optic nerve in the form of a pulse into the intermediate and middle brain (subcortical centers), and then into the occipital lobe of the cortex of the large hemispheres and is modified into a visual sensation. In the dark, visual purple is restored.

What is the difference between the analyzer and the sense organ? About this below.

Visual hygiene

Factors contributing to the preservation of vision:

• The light source is on the left;
• The workplace should be well lit;
• From the eye to the subject of consideration the distance should be about 30-35 centimeters.

Visibility deterioration is also caused by reading in the transport (because the ever-changing distance between the lens and the book leads to a weakening of the elasticity of the ciliary muscle and lens) or lying down. Keep your eyes from getting into them very bright light, dust and other particles. There are still no less important sense organs and analyzers. A test of biology can be done by everyone.

The organ of hearing

To the auditory organ belong the ear of the middle, outer and part of the inner ear.

The outer ear includes the auricle and an external auditory canal, terminating in the eardrum. In shape, the auricle resembles a funnel consisting of a fibrous tissue that is covered with skin and cartilage. The length of the external duct of the auditory is 2-5 cm. A special viscous sulfuric liquid is released by the special glands of the channel, which retards microorganisms and dust. Elastic and thin in 0.1 mm tympanic membrane contributes to the transfer to the middle ear of sound vibrations.

The middle ear is located behind the tympanic membrane in the temporal bone of the skull. Its drum cavity has a volume of about 1 cm ³ and contains three auditory ossicles: stapes, an anvil and a hammer. Through the eustachian (auditory) tube, the tympanum is connected to the nasopharynx. The pressure on both sides of the tympanic membrane is equalized by the auditory tube, and it maintains its integrity.

Very small in size auditory ossicles form a mobile chain with each other. The malleus (the most external bone) is connected to the eardrum, and its head is on the anvil with the help of a joint. The anvil, in turn, is attached to the stapes, and it is to the inner ear wall. The auditory ossicles perform the function of amplification 20 times and transfer the sound wave to the inner ear from the tympanic membrane.

The inner wall of the drum cavity, which separates the middle from the inner ear, has two windows (holes) - oval and round, which are tightened with a membranous membrane. In the membrane of the oval hole rests stapes.

Many people are interested in sense organs and analyzers. A biology test, for example, contains questions on this topic.

The inner ear is located in the temporal bone, it is a system of channels and cavities, which is called a labyrinth. Together they form a labyrinth of bone, and inside it is a labyrinth of membranous. Between the membranous and bone labyrinth the space is filled with a liquid called perilymph.

The membranous labyrinth inside is filled with a liquid called endolymph. Three departments are allocated in the inner ear: a snail, semicircular canals and the vestibule. To the auditory organ can be attributed only a cochlea - a bone channel, spirally wound in 2.5 turns. The cavity of this channel is divided into three parts by two membranes.

One membrane, the main membrane, consists of a connective tissue comprising about 24,000 thin fibers of different lengths and located across the course of the cochlea. The longest fibers are at the top of the cochlea, and the shortest ones are at its base. On these fibers there are 5 rows of sound-sensitive hair cells with a covering membrane growing above them. Together, these elements form the Corti's organ, that is, the receptor apparatus of the auditory analyzer.

The difference between the analyzer and the sensory organ is that the analyzer perceives information from the sense organ, which receives it from the surrounding world.

The mechanism of perception of sound

Liquids of the cochlea channels take stapes vibrations, which rests against the membrane of the oval window. This leads to fluctuations in the fibers of the main membrane by resonance. Including the high tone of the sounds causes the oscillations of the short fibers, which are located at the base of the cochlea, and the low tone causes the oscillations of the long fibers on the top. Hair cells at the same time touch the covering membrane, changing its shape.

Hair cells, touching the covering membrane, change shape. This leads to the appearance of excitation, transmitted to the midbrain as impulses along the fibers of the nerve of the auditory and then to the auditory zone of the cortex of the large hemispheres of the temporal lobe, where excitation passes into auditory sensation. The human ear can perceive a range of frequencies of sounds in 20-20000 Hertz.

Hygiene of the organ of hearing

To maintain hearing, it is necessary not to allow mechanical damage to the tympanic membrane. The auditory meatus and ears should be kept clean. If excess sulfur is accumulated in the ears, you need to contact a specialist. Strong and prolonged noises have a detrimental effect on the organ of hearing. It is very important to treat catarrhal diseases in a timely manner, since pathogenic bacteria can penetrate into the tympanic cavity through the Eustachian tube and provoke inflammation. We examined the analyzers and sense organs of man.

Other analyzers

There are also tactile, taste and olfactory analyzers. The touch is called irritation of several skin receptors. The taste receptors form the peripheral part of the taste analyzer (tongue, mouth mucosa). Its higher centers are located in the brain regions. The olfactory analyzer receives information from receptors located in the nasal mucosa. The sense of smell in humans is most weakly developed, unlike animals.

The work of the vestibular apparatus is interesting, it regulates the position and orientation of the body in space. Age and gender affect the effectiveness of analyzers. For example, women have a better sense of smell and perception of color shades. In men, taste buds work better.

The importance of sense organs and analyzers

These organs are extremely important for a person. Without them, survival would be difficult. Whoever is poorly developed by any sense organ or analyzer, there are peculiarities in the development and perception of the surrounding world. They are poorly oriented in space. Motor functions are impaired.