Retina: functions and structure. Functions of the retina

The ability to clear and clear vision is a unique feature not only of humans, but also of animals. With the help of vision, there is an orientation in space and the environment, obtaining a large amount of information: it is known that with the help of the eye, a person gets up to 90% of all information about objects and the environment. The unique structure and cellular composition allowed the retina not only to perceive the sources of light stimulation, but also to distinguish their spectral characteristics. Let's analyze how the retina functions, and the features of its neuronal organization. But only talk about its structure will not from the point of view of a person carrying the burden of scientific knowledge, but from the point of view of the average citizen.

Functions of the retina

Let's start with the highlights. The answer to the question of which basic functions of the retina is, is quite simple. First of all, this perception of light stimulation.

By its nature, light is an electromagnetic wave with a certain frequency of oscillation, which causes the perception of the retina in different colors. The ability to color vision is a unique feature of the evolution of mammals. With the help of scientific achievements, modern equipment, new luminescent chemical compounds, it was possible to look deeper into the structure of the organs of vision, to clarify the biochemical processes and better understand how the retina functions its own. And they, as it turns out, a lot, and each is unique.

Retina of the eye: structure and function

Many know that the retina is located inside the eye and is its innermost membrane. It is known that in its composition it contains so-called photosensitive cells. Immediately thanks to them and performs the retina function of photoreception.

Their names stemmed from the shape of the cells. Thus, rod-shaped cells were called "rods", and cells, similar to a chemical vessel called "flask" - received the name "cones".

Sticks and cones differ not only in their histological features. The main difference between them is how they perceive light and its spectral characteristics. The rods are responsible for the perception of the light flux in the twilight time - exactly when, as they say, "all cats are gray." But the cones are responsible for the perception of color vision.

Functional features of cones

Among the cones, there are three distinct classes: cones responsible for the perception of the green, red and blue parts of the spectrum, respectively. Each cone contributes to the formation of color vision, processing the image projected by the lens. In painting, the formation of the final color depends on the proportions in which the painter initially took paints. Similarly, the retina transmits information about the spectral characteristic of light: depending on how the cone pulses are discharged by each of the groups, we have a vision of a particular color.

For example, if we see a green color, then the cones responsible for the green region of the spectrum are most strongly discharged. And if we see red - then, respectively, for the red. Thus, the functions of the human eye's retina are not only in the perception of the light flux, but also in the primary evaluation of its spectral characteristics.

Layers of the retina, and why they are needed

Perhaps someone thinks that right after the lens the light directly gets on the rods and cones, and they already in turn connect with the fibers of the optic nerve and carry information to the brain. In fact, this is not so. Before reaching the sticks and cones, the light must overcome all layers of the retina (and there are 10 of them) and only after that act on the photosensitive cells (rods and cones).

The outer layer of the retina is the pigment layer. Its task is to prevent the reflection of light. This layer of pigment cells is a kind of black camera camera film (namely, black color does not create highlights, which means that the image becomes more clear, the reflections of light disappear). This layer provides the formation of a sharp image with the optical media of the eye. In the closest proximity to the layer of pigment cells, stick and cones adhere, and this feature makes it possible to see sharply. It turns out that the layers of the retina are located as if backwards. The innermost layer is a layer of specific cells that mediate incoming information from rods and cones through intermediary cells of the middle layer. Axons of these cells are collected together with the entire surface of the retina and leave the eyeball through a so-called blind spot.

In this place there are no photosensitive sticks and cones, and the optic nerve emerges from the eyeball. Moreover, it is here that the vessels that provide the trophic of the retina enter. The state of the body can be reflected on the state of the vessels of the retina, which is a convenient and specific criterion for diagnosing various kinds of diseases.

Localization of rods and cones

Nature is conceived so that the rods and cones are unevenly distributed over the entire surface of the retina. In the central fovea (the region of the best vision), the maximum concentration of cones is observed. This is due to the fact that this area is responsible for the clearest vision. As you move away from the central fossa, the number of cones decreases, and the number of rods increases. Thus, the periphery of the retina is represented only by rods. This feature of the structure provides us with a clear vision at a high level of illumination and helps to distinguish the outlines of objects at low.

Neuronal organization of the retina

Just behind the layer of rods and cones are two layers of nerve cells. These are layers of bipolar and ganglionic cells. In addition, there is a third (middle) layer of horizontal cells. The main purpose of this group is the primary treatment of afferent impulses, which comes from sticks and cones.

Interesting facts about the structure of the retina

Now we know what the retina is. The structure and functions of it have already been considered. It is also necessary to mention the most interesting facts related to this topic.

In order to reach the pigment layer, the light must pass through all layers of nerve cells, penetrate through the rods and cones and reach the pigment layer!

Another feature of the structure of the retina is the organization of providing a clear vision in the daytime. The bottom line is that in the central fossa each cone connects to its ganglionic cell, and as it moves to the periphery, one ganglion cell collects information from several rods and cones.

Retinal diseases and their diagnosis

So what is the function of the retina? Of course, this perception of the light flux, which form the refractive environment of the eye. Violation of this function leads to violations of clear vision. In ophthalmology there is a large number of diseases of the retina. These are diseases caused by degenerative processes, and diseases based on dystrophic and tumor processes, detachment, hemorrhages.

The main and primary symptoms that can talk about the diseases of the retina are a disorder of visual acuity. In the future, there may be optical circles, loss of visual fields and many other symptoms. It must be remembered that with a decrease in visual acuity, an ophthalmologist should be consulted immediately and examined.

Conclusion

Sight - a huge gift of nature, and the retina, functions and its structure - finely organized as a structural and functional element of the eyeball.

Timely consultation and preventive examinations at the ophthalmologist will help to identify the diseases of the visual analyzer and start treatment in time. Fortunately, modern medicine has unique technologies that allow literally in 20-30 minutes to get rid of visual disorders and again gain the ability to clear vision. And knowing what retina performs a function, you can restore it.