What is the structure of the human eye?

One of the most interesting topics in biology, in particular, in human anatomy is the structure of the eyes. Since ancient times, it is with the eyes that many beliefs, legends and myths are connected. Quite a lot of sayings, of which the most famous is: "The eyes are the mirror of the soul." But what exactly is the eye in fact? What can scientists tell about it? Ophthalmologists and biologists, anatomists, who have been fascinated by the human eye system for a long time, have found out that the eye, despite its small size, has a very complex device. What - read on.

Vision is not easy

The eye apparatus in anatomy is called stereoscopic. In the human body, he is responsible for ensuring that information is perceived correctly, correctly, without distortion. Thanks to the sight, the data is processed and then transferred to the brain.

The data on the object to the right of the brain are transmitted through the retina element located on the right. In this process, the optic nerve is involved. But what is on the left, perceives and studies the left part of the retina. The human brain is arranged in such a way that it combines without distortion the information obtained, thus forming an integral picture of the world around the beholder.

The eye structure provides binocular vision. Eyes form a very complex system in their device. It is due to it that a person is able to perceive, process data received from the outside world. One of the basic concepts for this system is electromagnetic radiation. It is based on human vision.

How does it work?

If you study the scheme of the human eye, you can see that the organ as a whole is similar to a ball. This is what caused the name of his "apple". The structure of the eyes is the interior and three successive outer layers:

• outer;
• vascular;
• retina.

Shells of the eye

So, what structure of the eye is outside? The uppermost part is called "cornea". This is a fabric that can be compared to a window that opens the view of the world around you. It is through the cornea that light enters the visual system. Since the cornea is convex, it is able not only to miss the rays of light, but to break them. The other part of the eye outside is called the "sclera". It is an insurmountable obstacle to light. Visually the sclera is like a boiled egg.

The next part, included in the so-called light-sensitive structures of the eye, is called the choroid. As it already follows from the name, it is formed by vessels through which oxygen and other necessary components and substances flow through the blood to the tissues. The shell has several components:

• Iris;
• Ciliary body;
• Choroid.

It so happened that people pay attention to the color of the eyes of the interlocutor. What it will be, determines the optical structure of the eye, namely the iris: it accumulates a specific pigment. Since the cornea allows you to see the iris of another person, you can determine what color the eyes of the person you met.

The pupil is located exactly in the center of the iris. It has a round shape, and changes its dimensions, focusing on the level of illumination. In addition, the expansion of the pupil is influenced by various factors (for example, taking medication).

Moving deeper

If you look at the iris, you can see the front camera. It is here that the mechanisms are located, due to which the intraocular fluid is produced. This substance circulates in the eye, washing its components. In the corner of the chamber there is a natural drainage system, through which the fluid flows from the eye. And in the depth of the ciliary body, you can find the accommodative muscle. Due to its functioning, the shape of the lens changes.

The choroid is even deeper. The structure of the human eye assumes the presence of the back of the vascular membrane, and it is she who wears this beautiful and sonorous name. The choroid is in constant contact with the retina, which is necessary for proper nutrition of the tissues.

The third shell

Since it was mentioned above that the structure of the eyes suggests three shells, it is necessary to talk about the retina. As its name indicates, this is a mesh shell. It is formed by nerve cells. The fabric lining the eye on the inner surface and guarantees high-quality vision if it is healthy.

The structure of the retina is such that an image from the outside world is projected here. But different parts of the tissue function differently. The maximum ability to see is provided by the macula, that is, the center. This is due to the high density of visual cone placement. The data received by the retina are transferred to a special nerve, through which they enter the brain, where they are promptly processed.

And what's inside?

What is the structure of the human eye, if you look under all three shells? Here you can find two cameras:

• Front;
• The back.

Both are filled with a special liquid. In addition, immediately there are:

• The lens;
• Vitreous body.

The first in its form resembles a lens that is convex on both sides. It is capable of refracting the light flux and letting it pass. Due to the lens operation, it becomes possible to focus the image on the reticular nerve tissue. But the vitreous body is most like jelly. Its main task is to prevent contact between the fundus and the lens.

Fibrotic and conjunctive membranes

Studying the location of the structure of the eye, begin with the conjunctiva. It is a transparent tissue outside the eye. It is her that covers the eyelids from within. Due to conjunctiva eyeballs can glide properly without damage.

Speaking about the functions of the eye structures, one should not lose sight of the fibrous membrane. Partially it is created from the sclera and has a high density, which guarantees the protection of fragile internal contents. This fabric is basic, but in front it is transparent and similar to glass on the watch. This segment of the fibrous membrane is commonly referred to as the cornea.

The transparent part of the shell is rich in nerve cells, which guarantees the conductivity of information. In the place where the sclera passes into the cornea, a limb is allocated. By this term, it is customary to understand the zone of stem cell concentration. Thanks to them, the outer part of the eye can be regenerated in a timely manner.

Eye cells

The anterior chamber is between the iris and the cornea, in particular, its angle, immediately and the above-mentioned drainage system. Disassembling the location of the shells and structures of the eye, a little farther into the depth you can see the lens. To ensure that he does not move from an anatomically correct position, nature has thin ligaments. They attach the organ to the ciliary body.

The front and back chambers are full of moisture that does not have color. This liquid nourishes the lens, supplies the nutrient components necessary for the functioning of the cornea. This is important, because these elements of the human vision system do not have their own blood supply.

Optics - a complex structure

Human vision is provided by the fact that there are refractive structures of the eye. It is due to the complex optics of the visual system that you can perceive data from the environment. Correct will be the perception of the space around him, if a person normally functions all organs and tissues:

• Auxiliary structures of the eye;
• Light-conducting;
• Perceiving.

With proper operation, there is no doubt about the clarity of vision.

Key elements of the optical system:

• cornea;
• The lens.

Note that the light-refracting structures of the eye include both the vitreous and moisture contained in the chambers of the eye. Therefore, vision will be good only if they:

• Transparent;
• Do not contain blood;
• Do not have turbidity.

Only when the rays of light pass through this system, they find themselves on the retina, where the image of the surrounding space is formed. Remember that it manifests itself:

• Inverted;
• Reduced.

In this case, nerve impulses are formed that enter the nerve and are transmitted to the brain via it. Neurons analyze the information received, so that a person gets a detailed idea of what surrounds him.

Cornea is a complex element of the eye system

To light-sensitive structures of the eye are different elements, not the last place in importance among which the cornea occupies. It forms five types of fabrics:

• Epithelium from the front;
• The Reichert plate;
• stroma;
• Descemet's fabric;
• endothelium.

Despite five components, the thickness of the cornea is only about a millimeter. Note: although the light-refracting structures of the eye are relatively large, the cornea is only a fifth of the fibrous membrane, that is, it is a tiny element of a complex complex.

Vertically, the cornea is about 11 mm, and in width - only a millimeter larger. The specific structure of the organ ensures its transparency: the cells that form the tissue are built according to a strictly structured scheme. Another tool used by nature when creating the cornea is the exclusion of blood vessels. But there are a lot of nerve endings. To the light refracting structures of the eye are several tissues, but this organ is characterized by a high refractive force, and it is one of the main.

Ciliary body

To the light-sensitive structures of the eye are also the components that constitute the ciliary body. It is part of the vascular membrane, representing its middle part, somewhat larger in thickness than other elements. Visually, the ciliary body is like a circular roller. Conventionally, scientists divide it into two elements:

• Vascular, that is, formed by vessels;
• Muscular, created by the ciliary muscle.

The first component combines about 70 thin processes capable of producing a liquid that provides nutrition and cleansing of the eye structure. From here, the cinnamon ligaments go, thanks to which the crystalline lens is firmly fixed on the place proper to it.

Retinitis as one of the key elements of the visual system

This tissue in anatomy is classified as an element of the visual analyzer. Its key feature is the ability to convert light pulses into nerve impulses, which are then processed by the human body.

The retina consists of six layers:

• Pigmented (same as - external). This element is able to absorb light, so that the phenomenon of scattering inside the eye is significantly reduced.
• Cell shoots. Scientists call them flasks and chopsticks. Rhodopsin and iodopsin are formed in the processes.
• Ocular fundus. This is an active element of the visual system. When the eye is examined, the ophthalmologist sees it.
• Vascular layer.
• A nerve disc that indicates the point where the nerve leaves the eye.
• The yellow spot, by which it is customary to understand that part of the tissues where the density of the cones is greatest, providing the possibility of a color vision of the surrounding space.

And what kind of liquid?

Above, I have already mentioned the eye fluid that is necessary for the normal functioning of the eye, filling the chambers. Visually and in structure, it is most like pure water. But the composition of the eye fluid is similar to blood plasma. It provides the correct power.

And how is the eye protected?

Considering such a delicate and fragile structure, one can not ignore the protective mechanisms provided by nature. The uppermost level of protection is the eye socket. It is a bone container. If you study the eye socket visually, it becomes clear that it is similar to a pyramid with four facets, but as if truncated. The top of the pyramid looks into the skull. The angle of inclination is 45 degrees. In depth, the human eye socket is 4 to 5 cm.

Pay attention: the eye socket is really bigger than the eyeball. It is necessary that the fatty body, as well as the nerve and muscles, the vascular system that ensures the correct functioning of the eye, should be placed here.

Eyelids are also a component of the structure of the eye

In a normal healthy human body, each eye is protected by two centuries:

• Lower;
• The upper one.

They help to protect the fragile system from getting objects from outside. Closing of the eyelids occurs unconsciously, the reaction is instantaneous not only with serious danger, but even with the blowing of the wind. Eyelids protect the eye when touching.

Blinking movements help clear the cornea of dust components. Thanks to them, the lacrimal fluid spreads evenly . The eyelids are also equipped with lashes growing on the edges. In our time they have become an important element of the notion of human beauty, but nature is conceived primarily to protect the visual system. Thanks to the cilia, the eyes are protected from dust and small debris that could damage the thin tissues.

Human eyelids are a rather thin layer of skin that forms folds. Under the epithelium is located the muscular layer:

• Circular, ensuring clamping;
• Lifting the eyelid from above.

But the inner side, as already mentioned, is lined with a conjunctiva.

How are tears formed?

With tears in human culture there are many signs, traditions, even images of thinking. The classical idea that has developed over the centuries: "Severe men do not cry," "Cry shamefully!". Is it true that tears are only an indicator of a person's mental weakness? Nature, creating a tear device, aspired to ensure the protection and correct functioning of the visual system, so in fact, even men can afford to cry, thereby purifying and protecting their eyes.

Tears are such transparent drops of a specific liquid, which is characterized by a weak alkalinity. The composition of the tear is very complex, but the key component is pure water. Normal allocation per day - about a milliliter. Tears protect the eyes and help feed tissues, and also to see better.

The lacrimal apparatus includes:

• Iron, producing tears;
• Points of tears;
• Channels;
• bag;
• duct.

The iron is in the eye socket, in the upper part of its wall, outside. It is here that tears are formed, which then fall into the channels intended for this, and thence to the eye surface. Surplus moisture moves downward, where a conjunctival arch is provided for this.

There are two lacrimal points: from above and from below. Both are in the inner corner, on the ribs of the eyelids. Through them, the tears through the canals pass into the sac close to the wing of the nose, then directly into the nose.

How many muscles are in the eye system?

If you study the muscular apparatus, it becomes clear that there are six muscles in the human eye. They are divided into the following groups:

• Obliques;
• Direct.

The first are divided into:

• Lower;
• The upper one.

Direct - these are the remaining four, which are known to science under the names:

• Lower;
• Upper;
• Central;
• Lateral.

In addition, the eye system includes the aforementioned mechanisms for lifting the upper eyelid and blinking.

Diseases associated with eye structure disorders

So it turns out that people suffer from eye diseases at different ages. Problems with the eyes persecute people regardless of their social status, wealth, living conditions, nationality. However, in some cases, it may be a predisposition associated with genetics, ecology or other factors. Usually, eye disorders are provoked:

• The wrong arrangement of one or another element of the structure;
• Defective part of the eye.

Distinguish diseases:

• Provoking a reduction in severity;
• Pathological functional disorders.

From the first group there are often:

• myopia;
• Farsightedness;
• astigmatism.

The second group includes:

• Glaucoma;
• Cataract;
• strabismus;
• Anophthalmos;
• retinal detachment;
• Myodescopy.

Most often there are recently myopia and farsightedness. In the first case, the eyeball is characterized by a length exceeding the norm. Because of this deformation, light is focused, not reaching the retina. Because of this, a person loses the ability to clearly see the world around him, especially objects in the distance. Usually prescribe glasses with negative diopters.

For farsightedness is characteristic of the opposite picture. The cause of the disorder is that the lens becomes inelastic or the eyeball decreases in length. The accommodation is weakened, the rays are focused beyond the retina, and the person can not clearly distinguish those objects that are nearby. In this case, write glasses with positive diopters.

Pay attention: glasses should be written out only by an ophthalmologist, it is unacceptable to assign lenses or glasses yourself. During the selection, eye measurement, the calculation of the distance between the pupils and careful examination of the fundus are performed, as well as the detection of the scale of the disturbances. When analyzing all the data obtained, the doctor recommends choosing those or other glasses, and also can advise you to perform an operation or in another way to correct the vision.

But astigmatism is much less common. At the same time, the brain can not receive correct information about the surrounding space due to a lens defect, the cornea, which causes the eye shell to lose the shape of the sphere.