The ability to perceive information about the world through vision is the most amazing and useful ability of a person. 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, from 70 to 80% of the information we perceive visually. The optical system of the eye, like a camera, has special mechanisms for capturing light reflected from the object and processing the information received. So what is the eye and how is our organ of vision arranged?
In the human skull, the organ of vision is located in the orbits. These cavities are formed by several bones at once, including the upper jaw, sphenoid, ethmoid, zygomatic, frontal. The orbit is a pyramid, the apex of which is facing the cranial cavity, and there is also an optic canal and an optic fissure through which nerves and blood vessels communicate with the organ of vision.
What is an eye? This is a spherical organ with a diameter of about 24-25 mm, which is filled inside with a liquid and consists of three shells. The movements of the eyeball are due to the work of six muscles: the upper, lower, internal, external, upper oblique and lower oblique. The auxiliary device also includes eyelids, eyelashes, eyebrows. Do not forget about the lacrimal gland, the secret of which washes and thereby moisturizes the surface of the eye.
The structure of the eyeball
What is an eye in terms of biology? This is an organ of vision that is filled with a clear liquid. Three membranes cover the eye: the sclera, choroid, and retina. Functions largely determine the structure of the eye, the photo of which is shown below.
The sclera is the thickest shell of the eye. It performs a protective function, and also forms a cornea in the front part, which enters the optical apparatus of the organ of vision. At the border of the cornea and the sclera itself, there is a limb zone.
The vascular membrane is penetrated by 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: they will be brown, green, gray or blue.
The retina is the innermost lining of the eye. Here are the visual pigments in the composition of the rods and cones, which are responsible for the perception of the picture. Actually, an initially inverted image is formed on the retina, 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: the front and back, which are filled with aqueous humor. The functions of this fluid are to feed the lens and cornea, as well as to refract the light beam.
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 former. Most of all, their concentration is in the region of the corpus luteum, where the vast majority of the light received is focused.
In the cones are the following pigments:
1. Eritlab - is responsible for the perception of shades of red and yellow.
2. Chlorolab - is responsible for the perception of the green spectrum of light.
3. Iodopsin - is responsible for the perception of cold blue and purple shades.
At night, the cones cease to function, and instead of them, rods are included in the work. These structures form a black and white image, and the pigment that is responsible for this is called rhodopsin. It has been proven that people with impaired vision see better in the dark.
What is an eye like an optical system?
In order for the image to appear, a beam of light reflected from the object must fall on the retina of the eye . This beam is refracted and focused using the complex optical apparatus of the eye. What structures form it?
The cornea has the greatest degree of refraction. She is the first structure on the path of the beam of light. Then it passes through the pupil and is slightly refracted due to the transition to a liquid medium, because there is watery moisture in the chambers of the eye. Then the light refracts once more when it reaches the lens of the eye.
Normally, the light beam should reach the corpus luteum on the retina. If he focuses, not reaching the retina, a disease occurs - myopia. If light enters the area behind the retina, then farsightedness occurs. Here is what the eye is and what functions this organ of vision performs.