What are the main elements of the eye and their function?
The eye can be called a complex optical instrument. Its main task is to “transmit” the correct image to the optic nerve.
The cornea is the clear membrane that covers the front of the eye. There are no blood vessels in it, it has a great refractive power. It enters into the optical system of the eye. The cornea is bordered by the opaque outer shell of the eye – the sclera. See the structure of the cornea.
The anterior chamber of the eye is the space between the cornea and the iris. It is filled with intraocular fluid.
The iris is shaped like a circle with a hole inside (pupil). The iris is made up of muscles that, when contracted and relaxed, change the size of the pupil. It enters the choroid. The iris is responsible for the color of the eyes (if it is blue, it means that there are few pigment cells in it, if there are a lot of brown). Performs the same function as the aperture in a camera, adjusting the light flux.
The pupil is a hole in the iris. Its dimensions usually depend on the light level. The more light, the smaller the pupil.
The lens is the “natural lens” of the eye. It is transparent, elastic – it can change its shape, almost instantly “directing focus”, due to which a person sees well both near and far. It is located in a capsule, held by a ciliary band. The lens, like the cornea, is part of the optical system of the eye.
The vitreous is a gel-like transparent substance located in the back of the eye. The vitreous body maintains the shape of the eyeball, participates in intraocular metabolism. It enters into the optical system of the eye. …
Retina – consists of photoreceptors (they are sensitive to light) and nerve cells. The receptor cells located in the retina are divided into two types: cones and rods. In these cells, which produce the enzyme rhodopsin, the energy of light (photons) is converted into electrical energy of the nervous tissue, i.e., a photochemical reaction.
The rods have a high light sensitivity and allow you to see in low light, they are also responsible for peripheral vision. Cones, on the contrary, require more light for their work, but it is they that make it possible to see small details (responsible for central vision), make it possible to distinguish colors. The greatest
the cone cluster is located in the central fossa (macula), which is responsible for the highest visual acuity. The retina is adjacent to the choroid, but loose in many areas. It is here that it tends to flake off in various diseases of the retina.
The sclera is the opaque outer shell of the eyeball, passing in the front of the eyeball into the transparent cornea. 6 oculomotor muscles are attached to the sclera. It contains a small number of nerve endings and blood vessels.
Choroid – lines the back of the sclera, the retina is adjacent to it, with which it is closely connected. The choroid is responsible for the blood supply to the intraocular structures. In diseases of the retina, it is very often involved in the pathological process. There are no nerve endings in the choroid, therefore, with its disease, pain does not occur, usually signaling any malfunction.
Optic nerve – With the help of the optic nerve, signals from nerve endings are transmitted to the brain.