Brief message about vision. Human vision organ: structural anatomy and physiology

Located in the eye socket (orbit). The walls of the orbit are formed by the facial and cranial bones. The visual apparatus consists of the eyeball, optic nerve and a number of auxiliary organs (muscles, lacrimal apparatus, eyelids). The muscles allow the eyeball to move. These are a pair of oblique muscles (superior and inferior muscles) and four rectus muscles (superior, inferior, internal and external).

Eye as an organ

The human visual organ is a complex structure that includes:

• Peripheral organ of vision (eyeball with appendages);
• Pathways (optic nerve, optic tract);
• Subcortical centers and higher visual centers.

The peripheral organ of vision (eye) is a paired organ whose structure allows it to perceive light radiation.

Eyelashes and eyelids perform a protective function. Accessory organs include the lacrimal glands. Tear fluid is needed to warm, moisturize and clean the surface of the eyes.

Basic structures

The eyeball is an organ of complex structure. The internal environment of the eye is surrounded by three membranes: outer (fibrous), middle (vascular) and inner (reticular). The outer shell mostly consists of opaque protein tissue (sclera). In its anterior part, the sclera merges into the cornea: the transparent part of the outer layer of the eye. Light radiation enters the eyeball through the cornea. The cornea is also necessary for the refraction of light rays.

The cornea and sclera are quite strong. This allows them to maintain intraocular pressure and maintain the shape of the eye.

The middle layer of the eye is:

• Iris;
• Choroid;
• Ciliary (ciliary) body.

The iris consists of loose connective tissue and network of blood vessels. In its center is the pupil - a hole with a diaphragm device. In this way, it can regulate the amount of light entering the eye. The edge of the iris passes into the ciliary body, covered with sclera. The ring-shaped ciliary body consists of the ciliary muscle, blood vessels, connective tissue and processes of the ciliary body. The lens is attached to the processes. The functions of the ciliary body are the process of accommodation and production. This fluid nourishes certain parts of the eye and maintains constant intraocular pressure.

It also produces substances necessary to ensure the process of vision. IN next layer The retina contains processes called rods and cones. Through the processes, the nerve stimulation that provides visual perception is transmitted to the optic nerve. The active part of the retina is called the fundus, which contains blood vessels, and the macula, where most of the cone processes responsible for color vision are located.

Shape of rods and cones

Inside the eyeball are:

• Intraocular fluid;
• Vitreous body.

The back surface of the eyelids and the front part of the eyeball over the sclera (up to the cornea) are covered by the conjunctiva. This is the mucous membrane of the eye, which looks like a thin transparent film.

The structure of the anterior part of the eyeball and lacrimal apparatus

Optical system

Depending on the functions performed by different parts of the visual organs, the light-conducting and light-receiving parts of the eye can be distinguished. The light-receiving part is the retina. The image of objects perceived by the eye is reproduced on the retina using optical system of the eye (light-conducting section), which consists of the transparent medium of the eye: the vitreous body, the moisture of the anterior chamber and the lens. But mainly the refraction of light occurs on the outer surface of the eye: the cornea and the lens.

Optical system of the eye

Light rays pass through these refractive surfaces. Each of them deflects the light beam. At the focus of the eye's optical system, the image appears as its inverted copy.

The process of refraction of light in the optical system of the eye is designated by the term “refraction”. The optical axis of the eye is a straight line that passes through the center of all refractive surfaces. Light rays emanating from objects at infinity are parallel to this line. Refraction in the optical system of the eye collects them at the main focus of the system. That is, the main focus is the place where objects at infinity are projected. Rays from objects that are at a finite distance are refracted and collected at additional foci. Additional focuses are further away than the main one.

When examining the functioning of the eye, the following parameters are usually taken into account:

• Refractive or refraction;
• Radius of corneal curvature;
• Refractive index of the vitreous body.

It is also the radius of curvature of the retinal surface.

Age-related development of the eye and its optical power

After a person is born, his visual organs continue to form. In the first six months of life, the macula region and the central region of the retina are formed. The functional mobility of the visual pathways also increases. During the first four months, the morphological and functional development of cranial nerves occurs. Until the age of two, the improvement of the cortical visual centers, as well as the visual cellular elements of the cortex, continues. In the first years of a child’s life, connections between the visual analyzer and other analyzers are formed and strengthened. The development of the human visual organs is completed by the age of three.

Light sensitivity in a child appears immediately after birth, but a visual image cannot yet appear. Quite quickly (within three weeks) the baby develops conditioned reflex connections, which lead to the improvement of the functions of spatial, object and.

Central vision develops in humans only in the third month of life. Subsequently, it is improved.

The visual acuity of a newborn is very low. By the second year of life it increases to 0.2–0.3. By the age of seven it develops to 0.8–1.0.

The ability to perceive color appears between the ages of two and six months. At the age of five, children's color vision is fully developed, although it continues to improve. Also gradually (approximately school age) reach the normal level of the border of the visual field. Binocular vision develops much later than other functions of the eye.

Adaptation

Adaptation is the process of adapting the organs of vision to the changing level of illumination of the surrounding space and objects in it. A distinction is made between the process of dark adaptation (changes in sensitivity during the transition from bright light to complete darkness) and light adaptation (when transitioning from darkness to light).

The “adaptation” of the eye, which perceived bright light, to vision in the dark develops unevenly. At first, sensitivity increases quite quickly, and then slows down. Complete completion of the dark adaptation process can take several hours.

Light adaptation takes a much shorter period of time - approximately one to three minutes.

Accommodation

Accommodation is the process of “adjusting” the eye to clearly distinguishing those objects that are located in space at different distances from the perceiver. The mechanism of accommodation is associated with the possibility of changing the curvature of the surfaces of the lens, that is, changing the focal length of the eye. This occurs when the ciliary body is stretched or relaxed.

With age, the ability of the visual organs to accommodate gradually decreases. Develops (age-related farsightedness).

Visual acuity

The concept of “visual acuity” refers to the ability to see separately points that are located in space at a certain distance from each other. In order to measure visual acuity, the concept of “visual angle” is used. The smaller the visual angle, the higher the visual acuity. Visual acuity is considered one of the most important functions of the eye.

Determining visual acuity is one of the key functions of the eye.

Hygiene is a part of medicine that develops rules important for preventing diseases and promoting the health of various organs and systems of the body. The main rule aimed at maintaining healthy vision is to prevent eye fatigue. It is important to learn how to relieve stress and use vision correction methods if necessary.

Visual hygiene also includes measures to protect the eyes from contamination, injury, and burns.

Hygiene

Equipping workplaces is part of the measures that allow the eyes to function normally. The organs of vision “work” best in conditions that are closest to natural. Unnatural lighting, low eye mobility, and dry indoor air can lead to visual impairment.

The quality of your diet has a big impact on your eye health.

Exercises

There is quite a large number of exercises to help maintain good vision. The choice depends on the state of a person’s vision, his capabilities, and lifestyle. It is best to get advice from a specialist when choosing certain types of gymnastics.

A simple set of exercises designed for relaxation and training:

1. Blink intensely for one minute;
2. “Blink” with your eyes closed;
3. Direct your gaze to a specific point located far from the person. Look into the distance for a minute;
4. Shift your gaze to the tip of your nose, look at him for ten seconds. Then again look into the distance, close your eyes;
5. Lightly tapping with your fingertips, massage the eyebrows, temples and infraorbital area. After this, you need to cover your eyes with your palm for one minute.

Exercises should be performed once or twice a day. It is also important to use the complex to relax from intense visual stress.

Video

conclusions

The eye is a sensory organ that provides the function of vision. Most of the information about the world around us (about 90%) comes to a person through vision. The unique optical system of the eye allows you to obtain a clear image, distinguish colors, distances in space, and adapt to changing light conditions.

The eyes are a complex and sensitive organ. It is quite, but also creating unnatural operating conditions. In order to maintain eye health, it is necessary to follow hygiene recommendations. If you experience vision problems or eye diseases, you should consult a specialist. This will help the person maintain visual functions.

We continue our series of Internet lessons on the world around us. Today we will talk about the senses. Probably, during the first period of the existence of life on Earth, our planet was a completely dark and silent world for living beings. Gradually they learned to smell, taste, touch, heat and cold, thereby acquiring the sense of touch, smell, and taste. With their help, ancient organisms searched for food and avoided danger...

Gradually, a world of colors and sounds opened up to living beings. Animals began to acquire protective coloring and learned to quietly sneak up on prey or hide from the enemy. Their perception became more and more perfect, the world of colors, sounds, and smells of living nature they perceived became more and more diverse.

The person has five senses - hearing, sight, smell, taste, touch . With their help, a person receives information about the world around him. A special organ is responsible for each of the senses. Name them...

That’s right, the organ of vision is the eye, the organ of hearing is the ear, the organ of taste is the tongue, the organ of touch is the skin and the organ of smell is the nose. And now about each in more detail.

Organ of vision - eye

Eyes- the most perfect and most mysterious organs in our body.

They say that “it is better to see once than to hear a hundred times.” With the help of vision, a person receives 90% of information about the world around him. With its help, a person sees light, determines the color, shape and size of objects, and their movement.

The eyes are located in eye sockets - special depressions of the skull. The eye is a very important organ and needs protection. Eyebrows and eyelashes protect it from sweat and dust.

Eyelids are like car wipers. About 25 times a minute a person moves his eyelids - blinks. This cleans the open part of the eye from dust and debris, moistens it, and prevents it from drying out. They are helped in this by the tear fluid that washes the cornea.

The eye itself is called differently eyeball (for your form) or vitreous . The back wall of the “apple” is lined with a black film - retina.

The eye is protected in front by a transparent cornea. Under the cornea there is a colored iris (iris), it is its color that determines the color of the eyes. The iris regulates the penetration of light into the eye. In the center of the iris there is a hole called pupil.In the dark, the pupil dilates to let more into the eye, and in bright light it narrows.

Located behind the pupil lens eyes, similar to a lens. Passing through the lens, light rays reach retina.The retina is as important to the eye as film is to a camera. It consists of light-sensitive cells, each of which sends its signal along the optic nerve to the cerebral hemispheres.From these signals, our consciousness puts together an image and gets an idea of ​​the object.

Do you know that there are two types of light-sensitive cells in the retina. Some people can distinguish colors, but only with sufficient lighting. Others perceive the world in shades of gray, but they are more sensitive to light. This is why for us “all cats are gray at night.”

Structure of the eye from 4.05 to 7.24 and 10.09 to 11.09

Do you know that...

• You see with your brain, not your eyes. The function of the eyes is to collect relevant information about the object you are looking at. This information is then sent to the brain. All information is analyzed in the brain.
• When exposed to daylight or too much cold, a person's eye color may change.
• There are approximately 1% of people on Earth whose iris color is different in their left and right eyes.
• The simplest gymnastics for the eyes: “Butterfly”. Blink frequently. It turns out that in front of the monitor, the eyes become lazy and stop blinking, and this harms our vision.
• The human eye distinguishes only seven primary colors - red, orange, yellow, green, blue, indigo and violet. But besides this, the eyes of an ordinary person can distinguish up to one hundred thousand shades, and the eyes of a professional (for example, an artist) up to a million shades.
• Indian yogis treat their eyes by looking at the sun, stars and moon. They believe that there is no light equal in strength to that of the sun. This exercise is best done at sunrise or sunset. But you should not look at it at noon.
• Future computers will be able to control eye movements. And not with a mouse and keyboard, as it is now.
• It's a paradox, but fast reading eye fatigue is less than with slow.

It's incredible, but the brain can be deceived... such deception is called optical illusions or optical illusions. For example, look at the following pictures...

Are they moving? But it only seems to us, in fact, they are just drawn.

Hearing organ - ear

A person receives a lot of information through hearing. These are sounds made by objects of inanimate and living nature, and human speech. Thanks to hearing, a person becomes aware of danger that he cannot see, for example, an approaching car.

The organ of hearing, the ear, is the second most important human sense organ. If you close your eyes, you will still feel where the top is, where the bottom is, whether the chair is tilted to the right or to the left. This is signaled by the balance organs located in the inner ear. Means the ear is the organ of hearing and balance .

What we usually call the ear is outer ear or Auricle . It picks up sounds and sends them into the ear canal, which ends eardrum .

Behind it there is a cavity middle earwith auditory ossicles.Sound vibrations in the air cause the eardrum to vibrate. They are amplified by the auditory ossicles and transmitted further - into inner ear (cochlea) , filled with liquid. The liquid causes sensitive hairs to vibrate. From them, a message about sound is transmitted along the auditory nerve to the brain.

Due to the fact that there are two hearing organs, we not only perceive sounds, but also determine where the source is.

In the inner ear there is organ of balance (vestibular apparatus).

The sense of balance is the ability to determine the position of the body in space, that is, to distinguish between up and down. Thanks to this feeling we walk without falling. But if you spend a long time on the rocking deck of a ship, your sense of balance becomes dulled: dizziness occurs. This condition is called seasickness.

Do you know that...

• Loud music is harmful to your hearing. This is not only a problem at concerts, but also in your headphones. By the way, listening to music through headphones increases the number of bacteria by 700 times.
• The ears clean themselves. Pores in the ear canal produce earwax, and small hairs called cilia push it out of the ears.
• The slightest sound you can hear is 0 decibels. Volume level jet engine is 120 decibels. If you are exposed to 90 decibels or more for 8 hours, it can damage your hearing. The figure shows a scale with sound decibels (sound power). The redder the scale, the higher the decibels, which means the sound is dangerous to hearing.

• The sound of the raging ocean that we hear when we put a seashell to our ear is not the ocean, but the sound of blood running through the veins in the ear.

Olfactory organ - nose

Why does a person need smell? It informs about the properties of the inhaled air, helps digestion, promotes the secretion of saliva and digestive juices and, therefore, maintains health. The sense of smell also warns a person about danger, for example, in case of a gas leak or fire.

The organ of smell is the nose. Inside the nose there is a mucous surface, and on it there are millions of nerve fibers. From various items many small particles are separated and float in the air. These invisible particles land on the nerve fibers of the nose and irritate them. This irritation is transmitted to the brain, to special center where the sensation of smell is formed. Particles of different substances irritate nerve fibers in different ways, which is why a person distinguishes odors.

Humans have many associations with smells. The sense of smell is most acute in summer and spring, especially in warm and humid weather. In the light the sense of smell is sharper than in the dark.

Do you know that if a person loses his sense of smell, then food loses taste for him, and such people are more likely to get poisoned because they cannot identify low-quality food.

The sensation of smell is inseparable from the substance itself. There are up to 400 thousand different odors perceived by humans. Note that there is still no scientific classification of odors and they are named according to the substance that produces them “herbs”, “the smell of a rose”, etc.

We smell only when we inhale. Bring an odorous substance to your nose. When you breathe normally, you will smell it. Hold your breath for a while, and you will not feel the smell, although its source is located near your nose. Make several sharp short sniffing movements. They are especially favorable for the work of the olfactory organ, which is located in the uppermost part of the nasal cavity.

Do you know that...

• A dog has 230 million olfactory cells in its nose, while humans have 10–11 million, which is twenty times less. However, the dog cannot find something that has no smell at all.
• People's favorite smells are the smells of fresh bread, freshly cut grass and coffee. The smells of bread and coffee not only stimulate the appetite, but also increase the desire to buy. That’s why big stores often smell like coffee and fresh pastries.
• A person who lives among a noisy civilization does not feel up to 70% of city smells. But, for example, an African who lives in wildlife, is able to catch the scent of his friend who walked along a forest path a few hours ago.

Taste organ - tongue

Experiment No. 1

Do you have three glasses with a yellowish liquid in front of you? What could it be? Do you have enough senses - sight, hearing, nose? If not, try to decide what to do….

That's right, you need to try the juice, that is, which sense organ to activate? That's right, that's TASTE.

There are billions of products on earth and each has its own taste. Incredibly, a person is able to distinguish all shades of this diversity.

First, let's find out WHY man is given the sense of taste?

When you were very, very little, you were real explorers. Anything that attracts babies' attention immediately goes into their mouth.

In this way, children try to obtain information about the objects they encounter. Even babies are able to recognize taste.

Taste is necessary for humans to recognize chemical composition any substance that gets inside. Means, taste is the protector of the body . Taste is the only sense organ on which our life directly depends!

By the way, our distant ancestors seemed curious about everything: taste told us what could be eaten and what not.

Intuitively, primitive people chose sweet fruits, because they contain a lot of sugar, which means a lot of calories. Calories are fuel for the body. Salty foods contain a lot of minerals, but bitter and sour foods were generally considered spoiled or poisonous.

And also taste brings joy .

Do you know that even a cow chooses juicier grass for herself?

I wonder why you need to enjoy food?

Do you know that the best connoisseurs tasty food- .... cockroaches. Even from a great distance, with the help of saliva, they transmit information that there is food. By the way, cockroaches love fruit juice.

Taste is one of the types of human sensations with the help of which he perceives the world. So why do we strive to eat especially tasty things?

It turns out that at first a person begins to eat because of a feeling of hunger. Hunger is a reaction of the body that forces us to look for “fuel” in order to survive.

Then the smart brain, while eating, begins to produce dopamine, a substance responsible for pleasure. As long as food enters the body, we experience pleasure and bliss. After this, we will always associate food with pleasure. Thus, the brain has protected our body, and from time to time we look for “something to snack on.”

The organ of taste is language.

As soon as food touches the tongue, taste buds record information and, through nerve impulses, the information enters the cerebral cortex, where, as if in a laboratory, taste recognition occurs.

Look at the picture... What do you see?...

Yes, lemon. How do you feel? It turns out that the tastes are preserved in memory!

By the way, people used to think that a snake’s tongue was a poisonous sting.

In fact, reptiles use their tongues for the same purposes as we do - they taste everything. The snake touches the object and takes a sample of everything that seems curious to it.

Different parts of the tongue are responsible for different taste sensations. The tongue recognizes four basic flavors: sweet, salty, bitter and sour.

The tip of the tongue recognizes sweet, the root of the tongue - bitter, the side part - sour, the area between the tip and the side part - salty.

Experiment No. 2

Try rubbing the tip of your tongue dry and licking the sugar... What do you feel?... Nothing. Now wet your sugar on your tongue with your saliva. What does it feel like?

Only dissolved substances can cause the sensation of taste.

Solids in the mouth dissolve saliva. From the sensitive areas of the tongue, signals travel to the brain, to a special center where taste sensations are formed.

The outside of the tongue is covered with countless papillae. They contain nerve endings that can sense what goes into the mouth. The tongue is one of the guardians of our body. If you accidentally take something nasty or stale into your mouth, your tongue will immediately report this to your brain, it will send an order to the muscle of your mouth, and without thinking, you will spit out what is harmful to the body.

Experiment No. 3

Organ of touch - skin

The sense of touch is the recognition of objects by touch. The organ of touch is the skin. It contains many nerve endings through which a person perceives hard and soft, cold and warm, smooth and rough, dry and wet. Thanks to these same nerve endings, a person experiences a feeling of pain. Signals from nerve endings enter a special brain center where the sensations of touch are formed.

Skin, it turns out, can “tell” a person about what surrounds him. The skin transmits information to what we touch. With our skin we can feel cold or heat, wind or heat, burning or blow.

All irritations of sensory cells are transmitted along the nerves to the brain. How does the brain avoid confusing signals from different sense organs? It turns out that the same signals travel through the visual, auditory or olfactory nerves. It is important which area of ​​the cerebral hemispheres they enter.

So, we perceive the world with all our senses at once. Their signals complement each other. The brain processes these signals and forms a single impression of what surrounds us.

Our body interacts with the environment using sense organs, or analyzers. With their help, a person is not only able to “feel” the external world, on the basis of these sensations he has special forms of reflection - self-awareness, creativity, the ability to foresee events, etc.

What is an analyzer?

According to I.P. Pavlov, each analyzer (and even the organ of vision) is nothing more than a complex “mechanism”. It is capable of not only perceiving signals environment and transform their energy into impulse, but also produce higher analysis and synthesis.

The organ of vision, like any other analyzer, consists of 3 integral parts:

The peripheral part, which is responsible for perceiving the energy of external irritation and processing it into a nerve impulse;

Pathways through which the nerve impulse passes directly to the nerve center;

The cortical end of the analyzer (or sensory center), located directly in the brain.

The rods consist of inner and outer segments. The latter is formed with the help of double membrane disks, which are folds of the plasma membrane. Cones differ in size (they are larger) and the nature of the disks.

There are three types of cones and only one type of rods. The number of rods can reach 70 million, or even more, while the number of cones is only 5-7 million.

As already mentioned, there are three types of cones. Each of them perceives a different color: blue, red or yellow.

Rods are needed to perceive information about the shape of an object and the illumination of the room.

From each of the photoreceptor cells there is a thin process that forms a synapse (the place where two neurons contact) with another process of bipolar neurons (neuron II). The latter transmit excitation to larger ganglion cells (neuron III). The axons (processes) of these cells form the optic nerve.

Lens

This is a biconvex crystal clear lens with a diameter of 7-10 mm. It has neither nerves nor blood vessels. Under the influence of the ciliary muscle, the lens is able to change its shape. It is these changes in the shape of the lens that are called accommodation of the eye. When set to distance vision, the lens flattens, and when set to near vision, it enlarges.

Together with the lens, it forms the light-refracting medium of the eye.

Vitreous body

It fills all the free space between the retina and the lens. It has a jelly-like transparent structure.

The structure of the organ of vision is similar to the principle of the camera. The pupil acts as a diaphragm, narrowing or expanding depending on the lighting. The lens is the vitreous body and the lens. Light rays hit the retina, but the image comes out upside down.

Thanks to the light-refracting media (thereby the lens and the vitreous body), a beam of light falls on the yellow spot on the retina, which is best zone visions. Light waves reach the cones and rods only after they have passed through the entire thickness of the retina.

Locomotor system

The motor apparatus of the eye consists of 4 striated rectus muscles (inferior, superior, lateral and medial) and 2 oblique muscles (inferior and superior). The rectus muscles are responsible for turning the eyeball in the appropriate direction, and the oblique muscles are responsible for turning around the sagittal axis. The movements of both eyeballs are synchronous only thanks to the muscles.

Eyelids

Skin folds, the purpose of which is to limit the palpebral fissure and close it when closed, provide protection to the eyeball from the front. There are about 75 eyelashes on each eyelid, the purpose of which is to protect the eyeball from foreign objects.

A person blinks approximately once every 5-10 seconds.

Lacrimal apparatus

Consists of the lacrimal glands and lacrimal duct system. Tears neutralize microorganisms and can moisturize the conjunctiva. Without tears, the conjunctiva of the eye and the cornea would simply dry out, and the person would go blind.

The lacrimal glands produce about one hundred milliliters of tears every day. Interesting fact: Women cry more often than men, because the secretion of tear fluid is promoted by the hormone prolactin (of which girls have much more).

Basically, tears consist of water containing approximately 0.5% albumin, 1.5% sodium chloride, some mucus and lysozyme, which has a bactericidal effect. Has a slightly alkaline reaction.

Structure of the human eye: diagram

Let's take a closer look at the anatomy of the organ of vision with the help of drawings.

The figure above schematically shows parts of the organ of vision in a horizontal section. Here:

1 - tendon of the middle rectus muscle;

2 - rear camera;

3 - cornea of ​​the eye;

4 - pupil;

5 - lens;

6 - anterior chamber;

7 - iris;

8 - conjunctiva;

9 - tendon of the rectus lateral muscle;

10 - vitreous body;

11 - sclera;

12 - choroid;

13 - retina;

14 - yellow spot;

15 - optic nerve;

16 - blood vessels of the retina.

This figure shows the schematic structure of the retina. The arrow shows the direction of the light beam. The numbers indicate:

1 - sclera;

2 - choroid;

3 - retinal pigment cells;

4 - sticks;

5 - cones;

6 - horizontal cells;

7 - bipolar cells;

8 - amacrine cells;

9 - ganglion cells;

10 - optic nerve fibers.

The figure shows a diagram of the optical axis of the eye:

1 - object;

2 - cornea;

3 - pupil;

4 - iris;

5 - lens;

6 - central point;

7 - image.

What functions does the organ perform?

As already mentioned, human vision transmits almost 90% of the information about the world around us. Without him, the world would be the same and uninteresting.

The organ of vision is a rather complex and not fully studied analyzer. Even in our time, scientists sometimes have questions about the structure and purpose of this organ.

The main functions of the organ of vision are the perception of light, forms of the surrounding world, the position of objects in space, etc.

Light is capable of causing complex changes in and is thus an adequate stimulus for the visual organs. It is believed that rhodopsin is the first to perceive irritation.

The highest quality visual perception will be provided that the image of the object falls on the area of ​​the retinal spot, preferably on its central fovea. The further from the center the projection of the image of an object, the less distinct it is. This is the physiology of the organ of vision.

Diseases of the organ of vision

Let's look at some of the most common eye diseases.

1. Farsightedness. The second name for this disease is hypermetropia. A person with this disease has difficulty seeing objects that are close. Usually reading and working with small objects are difficult. It usually develops in older people, but can also appear in young people. Farsightedness can be completely cured only through surgical intervention.
2. Myopia (also called myopia). The disease is characterized by the inability to clearly see objects that are far enough away.
3. Glaucoma - increased intraocular pressure. Occurs due to impaired circulation of fluid in the eye. It is treated with medication, but in some cases surgery may be required.
4. Cataract is nothing more than a violation of the transparency of the lens of the eye. Only an ophthalmologist can help get rid of this disease. Surgery is required to restore a person's vision.
5. Inflammatory diseases. These include conjunctivitis, keratitis, blepharitis and others. Each of them is dangerous in its own way and has various methods Treatments: Some can be cured with medication, while others can only be cured with surgery.

Disease Prevention

First of all, you need to remember that your eyes also need to rest, and excessive stress will not lead to anything good.

Use only high-quality lighting with a lamp power of 60 to 100 W.

Do eye exercises more often and be examined by an ophthalmologist at least once a year.

Remember that eye diseases are a fairly serious threat to your quality of life.

One of the main organs that is directly related to the perception of the surrounding world is the ocular analyzer. The organ of vision plays a primary role in the diverse activities of man; in its evolution it has reached perfection and performs important functions. With the help of the eye, a person selects colors, captures streams of light rays and directs them to light-sensitive cells, recognizes three-dimensional images and distinguishes objects at different distances from him. The human organ of vision is paired and is located in the cranial orbit.

The eye (the organ of vision) is located in the skull in the orbital cavity. It is held in place by several muscles located at the back and sides. They strengthen and provide motor activity and focusing of the eye.

The anatomy of the organ of vision distinguishes three main parts:

• eyeball;
• nerve fibers;
• auxiliary parts (muscles, eyelashes, glands that produce tears, eyebrows, eyelids).

The shape of the eyeball is spherical. Only the front, which consists of the cornea, is visually visible. Everything else lies deep in the eye socket. The average size of the eyeball in an adult is 2.4 cm. It is calculated by measuring the distance between the anterior and posterior poles. The straight line that connects this gap is the external (geometric, sagittal) axis.

If we connect the inner surface of the cornea to a point on the retina, we get the internal axis of the body of the eye, which is located at the posterior pole. Its average length is 2.13 cm.

The main part of the eyeball is a transparent substance, which is enveloped in three membranes:

1. Protein is a fairly strong tissue that has connective characteristics. Its functions include protection against injuries of various types. The protein coat covers the entire visual analyzer. The front (visible) part is transparent - this is the cornea. The sclera is the posterior (invisible) protein membrane. It is a continuation of the cornea, but differs from it in that it is not a transparent structure. The density of the protein shell gives the eye its shape.
2. The middle ocular membrane is a tissue structure that is penetrated by blood capillaries. Therefore, it is also called vascular. Its main functionality is to nourish the eye with all the necessary substances and oxygen. It is thicker in the visible part and forms the ciliary muscle and body, which, by contracting, guarantees the ability of the lens to bend. The iris is an extension of the ciliary body. It consists of several layers. It is here that there are cells responsible for pigmentation, they determine the shade of the eyes. The pupil looks like a hole that is located in the center of the iris. It is surrounded by circular muscle fibers. Their functions include pupil contraction. Another group of muscles (radical), on the contrary, dilates the pupil. All together help the human eye regulate the amount of light that penetrates inside.
3. The retina is the inner layer and consists of the posterior and visual parts. The anterior retina has pigment cells and neurons.

In addition, the organ of vision has a lens, aqueous humor and vitreous body. They are an internal component of the eye and part of the optical system. They bend and conduct light rays through the internal structure of the eye and focus the image on the retina.

Thanks to its optical abilities (changes in the shape of the lens), the organ of vision transmits images of objects that are located at different distances from the visual analyzer.

Anatomy of the auxiliary parts of the visual analyzer

The anatomy and physiology of the organ of vision also consists of an auxiliary apparatus. It performs a protective function and provides motor activity.

Tear, which is produced by special glands, protects the eye from hypothermia, drying out and cleanses it of dust and debris.

The entire lacrimal apparatus consists of the following main parts:

• lacrimal gland;
• drainage ducts;
• lacrimal sac;
• tear duct;
• nasolacrimal duct.

Eyelids, eyelashes and eyebrows also have protective abilities. The latter protect the visual apparatus from above and have a hairy structure. They wick away sweat. The eyelids are folds of skin that, when closed, completely hide the eyeball. They protect the visual organ from harsh light and dust. The inside of the eyelid is covered with conjunctiva, and their edges are covered with cilia. The sebaceous glands are also located here, the secretion of which lubricates the edge of the eyelids.

The general structure of the organ of vision cannot be imagined without the muscular system, which ensures normal motor activity.

It consists of 6 muscle fibers:

• bottom;
• top;
• medial and lateral rectus;
• oblique.

The work of the entire visual analyzer depends on their ability to contract and relax.

Stages of development of the human eye and the secrets of good vision

Anatomy and physiology of the organ of vision has different characteristics at all stages of its formation. During the normal course of pregnancy in a woman, all structures of the eye are formed in a clear sequence. Already in a fully formed 9-month-old fetus, the organ of vision has all fully developed membranes. But there are some differences between the eye of an adult and a newborn (weight, shape, size, physiology).

The development of the eye after birth goes through certain stages:

• in the first six months, the baby’s macula and retina (fovea) develop;
• during the same period, the development of the visual pathways occurs;
• the formation of nervous reaction functions occurs before 4 months of age;
• the final formation of cerebral cortex cells and their centers occurs within 24 months;
• During the first year of life, connections between the visual apparatus and other sense organs develop.

Thus, the organ of vision is gradually formed and improved. Its development continues until human puberty. During this period, the child’s eyes almost completely correspond to the parameters of an adult.

Starting from birth, a person must maintain visual hygiene, which will ensure long-term operation of the analyzer. This is especially important when its development and formation occurs.

During this period, children's vision often deteriorates, which is associated with excessive eye strain, failure to follow basic rules, for example, when reading, or a lack of essential vitamins and microelements in the diet.

Let's look at some of the important rules visual hygiene, which must be observed not only during the period when development occurs, but throughout life:

1. Protect your eyes from mechanical and chemical negative impact.
2. When reading, provide good lighting, which should be located on the left side. But at the same time it should not be too bright, as this renders light-sensitive cells unusable. Provide soft lighting.
3. The distance from the book to the eyes should not be less than 35 cm.
4. Do not read while lying down in public transport. Constant movement and changing the distance between the book and the eye apparatus leads to rapid fatigue, constant changes in focus and improper muscle function.
5. Provide your body with enough vitamin A.

The eye is a complex optical apparatus human body. Its main function is to transmit images to the cerebral cortex for analysis of surrounding objects. At the same time, the brain and visual organs are closely connected. Therefore, it is very important to maintain the basic functions of our visual analyzer.

With the help of the organs of vision, a person perceives the world around him. It is known that people receive most of the information visually. Speech was formed and reached the proper level of development much later.

In addition, when it comes to communication, the body and its movements are much more difficult to control than words. Therefore, there are various theories about recognizing body language visually; this is a kind of test for the sincerity of the interlocutor, a way to find out the unconditional truth.

What are the consequences of eye diseases?

This is an important part of the body. Nowadays people don’t think as much as before about the safety of the world around them. But the task of adapting to the terrain is still important, and it is performed using the eye.

Injury is still possible if there is insufficient attention to environmental circumstances. No one will dispute the statement that as vision decreases, the quality of life also deteriorates. Lack of vision is an absolute indication for determining disability, because normal life activities are significantly complicated, and a person loses many opportunities.

The development of the organ of vision has led to improvements in some aspects, but the set of functions has remained the same. The main task is to provide a three-dimensional and comprehensive visual perception of the outside world.

Anatomy and physiology of the eye

The anatomy of the eye itself is very complex. The system has been improved over thousands of years, and has reached an ideal level of development for human life. Many people are surprised to learn that animals and insects have a different organ structure, which allows for increased visibility or clarity of the image in certain conditions.

But for a person, such a device is ideal; based on the placement of the eyes, some theorists even conclude that a person belongs to predators or herbivores, but this is not the main task. The main thing is that this structure of the organ of vision allowed the population to survive and take a leading position in the animal world.

The core of the entire system is the eyeball. The fact that this organ has a round shape has been clear for a long time. But its internal components were studied relatively recently, when the appropriate tools appeared.

And inside the eyeball there are important components, such as the lens, a specific liquid. In addition, there is a retina and three membranes. Each performs its assigned important role and ensures the perception of light flux.

Anatomy of the organ of vision:

Structural features

The human organ of vision, its structure and functions, is specific and all its components "sharpened" initially for solving survival problems. The lens is impervious; it does not have any components for this. But it is moved by muscles, which are very sensitive to various external changes. This ensures far or near vision.

The eyeball performs an important function. It is this that ensures the perception and transmission of external signals. But in itself it is very sensitive, susceptible to infections and injuries. This fragile structure is protected by eyelids that close and open.

A person cannot always fully control these movements. This reflex is one of the unconditioned ones. This is quite logical, otherwise a person would not have time to react to changes in the external environment properly.

This feature is associated with the difficulty of using eye drops and wearing lenses. But a person copes with this complexity by training his muscles and reflexes. At the right moment, however, they will work just as effectively.

There is also a place called a blind spot. It doesn’t play a big role; there are simply no receptors here. This is where the optic nerve exits the retina.

Special receptors are responsible for receiving light signals. They are concentrated in the inner shell, called rods and cones. Cones are responsible for daytime perception, rods for nighttime perception. The cones are located directly opposite the pupil. This area is also called the macula macula.

Receptors consist of special substances. They are able to quickly disintegrate and recover. Therefore, with a quick change from darkness to light or vice versa, a person gets used to the situation for some time.

The structure of the organs of vision is quite complex. This is a very sensitive system. All components are involved in the refraction of light flows and the perception of visual objects. There is also a muscle that moves the eyeball, helping to increase vision and angle of perception. Eyebrows, eyelashes, etc. also perform protective functions.

This is the physiology of the visual system, since it was formed under the influence of evolutionary processes.

Functions of the visual system and possible diseases

The structure of the human visual organ is precisely this, since the entire system performs special functions. They have already been mentioned in passing, but are worth mentioning separately.

So, the eyes provide perception of the outside world with the help of visual images. Thus, information is assimilated, a person receives the data necessary to ensure normal life activities. Objects can be differently located in space; the organ of vision is responsible for correct perception from different angles. This is ensured through complex modifications of light fluxes, but the efficiency of the organ is great if its state of health is satisfactory.

Information is also needed to adapt to conditions external environment. A person learns about possible danger through vision. He has the opportunity to prepare for it. Human eyes perform important functions; if vision deteriorates even slightly, this immediately affects the quality of life.

Why do illnesses arise and the functioning of the entire system deteriorate? More often than not, such a sensitive organ simply wears out over time. Therefore, various age-related ailments appear, such as farsightedness and myopia. Excessive stress and strain can also cause vision impairment.

This is especially true now, since computers are used everywhere for work. The eye has not yet been able to adapt to such an excessive load, so you need to carefully monitor its condition and take all measures to prevent diseases.

At the physiological level, deterioration in the perception of objects is associated with a change in the length of the eyeball. The lens can also lose its elasticity over time. The required clarity of perception is no longer achieved. This is a widespread problem, which is also associated with environmental degradation.

Ailments associated with the mucous membrane and the appearance of various neoplasms are also possible. Such ailments can often be cured only with surgical intervention. And eye surgeries are very complex and dangerous; this is a feature of physiology.

Previously it was believed that it was impossible to restore vision. Now operations are being used, and successfully, that allow you to restore it to 100% level. But the experts themselves talk about the presence of contraindications and possible complications. Therefore, it is easier to follow preventive measures and organize the workplace correctly.

The required level of illumination must always be provided. It is very easy to guess. It should be taken into account that open sources of artificial light can have a bad effect on the eyes.

Therefore they need to be covered. Don't strain your eyes for too long. You need to take breaks from working at the computer and reading.

The distance to the book or computer should be appropriate. Moreover, radiation from a computer is also harmful. It is not advisable to read on the bus, just as it is not advisable to read while lying on the sofa.

It is worth remembering the basic rules of care. Do not rub your eyes too hard with your hands, as infection may spread. If inflammation occurs, you can use tea infusion as a lotion. And it is necessary to ensure a constant supply of vitamin A - the physiology of the organ is such that it constantly needs it.