A window into the world. Human organs of vision

The knowledge of the diversity of the surrounding world is facilitated by the senses. Eyes provide us with ninety percent of all incoming information. The organs of human vision are so closely connected with the brain that they are entrusted with the basic function of the connection of the nervous system with the surrounding world. The material for the photosensitive membrane of the eye is the cerebral nervous tissue. Human organs of vision use the peripheral part of the image analyzer - photoreceptors. As a conductor, the visual analyzer uses the optic nerve. All this complex mechanism works on the central part, which is concentrated in the visual zone, in the occipital lobe of the cortex of the cerebral hemispheres.

Speaking of the organs of vision, we often represent those elements that are outside. First of all, it is a pair of eyeballs (eyes) and organs performing auxiliary functions. These include eyelids, eyebrows, eyelashes, lacrimal glands and eye muscles. The eyelids are skin folds, they limit the eye gap and close it if necessary. On the inner surface of the century there is a mucous membrane, which specialists-ophthalmologists call a conjunctiva. The main function of the eyelid is the lubrication of the eye's surface with tear fluid, as well as the protection of this surface from drying and mechanical influences. In a normal state, a person blinks at intervals of every five seconds.

The pride of any beauty - eyelashes - are on the edges of the eyelids, they are arranged in 2-3 rows, their number reaches eighty. They perform a protective function, cautioning against the ingress of foreign particles into the mucous membrane. The lacrimal gland plays a huge role in ensuring the normal functioning of the eye. It is located outside in the upper corner of the eye. She constantly and continuously produces a special secret - tears. The daily volume reaches 100 ml. A tear through the nasolacrimal canal flows constantly into the nasal cavity. Chemically, the tear is a 1.5 percent solution of common table salt (NaCl), which contains a bactericidal substance (lysozyme). A tear performs several functions. To wash the surface of the eyeball, moisturize it and protect it from bacteria and foreign particles, the task of removing the substance, the product of nervous tension and emotional stress is added.

The organs of vision of a person are in constant motion. For the movement of the eyeballs meet the eye muscles. In the arsenal of the human eye there are four straight and a pair of oblique muscles. Their synchronous work ensures the installation of the visual axes of each eye, so that they converge on the subject that is being examined.

The eyeball is a spherical natural lens, the diameter of which reaches two and a half centimeters. It is restricted to three shells. External called fibrous (white), the average was called vascular, and the inner called light-sensitive (retina).

The organs of human vision are a complex natural mechanism that requires careful treatment for normal functioning. Just like the human circulatory system, the eyes perform their work with the only difference that they take a little rest during the person's sleep, but their functioning does not stop, but only goes into a more "economical regime".

For the normal operation of the eyes, you must strictly adhere to the hygiene of visual work. This includes the division of working time into workloads and periods of short-term breaks. A set of exercises has been developed that allow not only to train and tonify the muscles of the eyes, but also to stabilize the lens and the course of the nervous processes.

Taking care of your own vision will be a guarantee that you will be able to fully enjoy the diversity of colors of the world around us for a long time.