The ability to perceive information about the world around us with the help of vision is the most amazing and useful human ability. We capture a picture of what is happening, like a photo. The eye is that "optical device" that allows us to see the world around us and send information about it.
The eye is the human organ of vision
According to psychologists, we perceive visually from 70 to 80% of information. The optical system of the eye, like a camera, has special mechanisms for capturing light reflected from an object and processing the information received. So what is the eye and how does our organ of vision work?
In the human skull, the organ of vision is located in the eye sockets. These cavities are formed by several bones at once, including the upper jaw, sphenoid, ethmoid, zygomatic, frontal. The eye socket is a pyramid, the top of which faces the cranial cavity, and here are the optic canal and optic fissure, through which nerves and vessels communicate with the organ of vision.
What is an eye? It is a spherical organ with a diameter of about24-25 mm, which is filled with liquid inside and consists of three shells. The movements of the eyeball are due to the work of six muscles: superior, inferior, internal, external, superior oblique and inferior oblique. The auxiliary apparatus also includes eyelids, eyelashes, eyebrows. Do not forget about the lacrimal gland, the secret of which washes and thus moisturizes the surface of the eye.
The structure of the eyeball
What is the eye in terms of biology? This is the organ of vision, which is filled with a transparent liquid. Three membranes cover the eye: sclera, choroid and retina. Functions largely determine the structure of the eye, the photo of which is shown below.
The sclera is the thickest layer of the eye. It performs a protective function, and also forms the cornea in the anterior part, which enters the optical apparatus of the organ of vision. There is a limbus zone on the border of the cornea and the sclera proper.
The choroid is permeated with numerous vessels, the task of which is to nourish the entire organ. This shell forms a ciliary, or ciliary, body (muscle), which is responsible for changing the curvature of the lens, i.e. for accommodation. Also a derivative of the choroid is the iris, which has a hole in the middle - the pupil. The color of the iris largely determines the color of the eyes themselves: will they be brown, green, gray or blue.
The retina is the innermost layer of the eye. Here are visual pigments in the composition of rods and cones, which are responsible for the perception of the picture. Actually, on the retina is formed initiallyan inverted image, information about which is then transmitted to the occipital zone of the cerebral cortex.
The iris divides the area between the cornea and the lens into two chambers: anterior and posterior, which are filled with aqueous humor. The functions of this fluid are to nourish the lens and cornea, as well as to refract a beam of light.
Basic visual pigments
The optical system of the eye allows you to perceive a color image during the day and black and white at night. Structures such as cones are responsible for the first. Most of all, their concentration is in the corpus luteum, where the vast majority of the received light is focused.
Cones contain the following pigments:
1. Eritlab - responsible for the perception of shades of red and yellow.
2. Chlorolab - responsible for the perception of the green spectrum of light.
3. Iodopsin - responsible for the perception of cold blue and purple hues.
At nighttime, the cones cease to function, and instead of them, sticks are included in the work. These structures form a black and white image, and the pigment responsible for this is called rhodopsin. Visually impaired people have been proven to see better in the dark.
What is the eye as an optical system?
In order for an image to appear, a beam of light reflected from an object must hit the retina of the eye. This beam is refracted and focused by the complex optical apparatus of the eye. What structures form it?
The cornea has the highest degree of refraction. It is also the first structure on the path of the light beam. Then it passes through the pupil and is slightly refracted due to the transition to a liquid medium, because. there is aqueous humor in the chambers of the eye. Further, the light is refracted again when it reaches the lens of the eye.
Normally, a beam of light should reach the corpus luteum on the retina. If it focuses, not reaching the retina, a disease occurs - myopia. If light enters the area behind the retina, farsightedness occurs. Here is what the eye is and what functions this organ of vision performs.
