The eye, like an optical system, consists of many components. Each of the components is unique and unrepeatable in its own way. There are 12 parts in total. They all help us see the world.
Components visible from the outside
The first component we see is the eyeball. Its diameter is usually 2.5 cm. Some people have more, others
x - less.
The apple is covered with three shells. The first is a hard sclera, which protects it from various damages. Next is the choroid. She nourishes the eye. And finally, the last one is rainbow. It is this shell that gives the "color" to a person's eyes. It has a small hole: the pupil.
What's inside, or how do we see?
The eye, like an optical system, works constantly. Even when we sleep, the apple is in motion. Once in any room, this complex device begins to work continuously.
First the pupil is activated. It narrows or expands depending on the degree of illumination of the place. If it is dark, it becomes larger; if it is light, it becomes smaller.
Further information goes to the lens of the eye (biconvex lens) and the cornea. Together they formkind of focusing lens. Yeah, eye like
optical system is a very complex and unique device.
The cornea is a more important component than the lens as it plays a large role in focusing and refraction of light. She has a stable character - she is motionless. But the eye cannot see near and far at the same time. This is where the lens comes to the rescue. Instantly changing its curvature, it allows you to see. Such a curvature after aiming the eye at an object is called accommodation.
At the same time, in order to consider what is close, the muscles have to strain very hard. Such overexertion can lead to nearsightedness or farsightedness.
Even deeper
Being refracted, the rays fall on the retina, where an inverted image of the object is immediately formed. However, the eye, as an optical system, is unique, and the image that is convenient for us enters the brain.
The retina also contains visual receptors: rods (130 million) and cones (7 million). The first are responsible for vision in the dark, the second - in the light. Thus, it is the cones that, after a complex photochemical reaction, supply a color image to the brain. In total, there are three shades (red, green, blue-violet), which, when mixed, give such an image rich in colors. It has been proven that blue cone men have very few
lo, and they hardly distinguish this color.
Exactly opposite the pupil is a yellow spot or a place where only cones are located. This is where the clearest image is projected. When a person looks at an object, the eye automatically adjusts so that part of the object falls into this zone. Then the picture is transmitted to the brain without distortion.
Information to the center of all human life comes through the optic nerve. It is he who serves as a conductor that transmits the picture.
The drainage system of the eye performs a protective function. It is she who causes tears that moisturize the whole device. Moreover, this liquid washes away dirt and protects against pathogenic bacteria. Tears are very necessary for our body.
