Sense organs

Have you noticed how many different things our body can do? We can perceive the environment by seeing, hearing, smelling, feeling, tasting. We have received information about our surroundings. By processing them in our brain, we interpret them as danger signs, pleasant or unpleasant sensations, etc. After this interpretation, we respond to the stimuli of the environment by interacting with it.
Our bodies can do many things that a machine cannot.
How do you know what is happening around you? We receive information about the environment through five senses: eyesight, hearing, taste, smell and tact.

The luminous energy (light) comes to our eyes bringing information of what is around us. Our eyes can transform the light stimulus into another form of energy (action potential) that can be transmitted to our brain. The latter is responsible for creating an image from the information taken from the medium.

The eye is covered by three membranes: sclera, choroid and retina. The sclera is the outermost layer, which we call the "white of the eye."

The anterior part of the sclera consists of the cornea, which is a curved and transparent membrane through which light passes.

In addition to the cornea, there is the choroid - this intermediate membrane has many blood vessels that nourish the eye cells.

In the anterior part of the choroid, under the cornea, is the iris, which is the colored part of the eye. In the center of the iran, there is an opening, the pupil, through which light enters the eye. The color of the iris depends on the amount of melanin (also responsible for the color of the skin) that the person has. The amount of pigment is hereditary, that is, it is determined by the genes.

Observe your eyes in a mirror. You will see a very black "ball" in the center of the colored region. It is the pupil. But what is the pupil?

Nothing more than a hole that lets the light through. Have you ever left a dark place and entered another bright room? What happened? Chances are you were blinded, that is, you couldn't see for a few seconds. The colored region of your eyes is known as iris.. It is a delicate muscle that makes your pupil large or small according to the amount of light it receives.

When the amount of light is small, you need to enlarge this hole to capture as much light energy as possible. When the luminosity is high, the iris diminishes the pupil, reducing the light input, so that your eyes do not receive so much "information" and are unable to transmit them to the brain.

Inner parts of the eye

The transparent structures inside the eye allow light to cross the eyeball and reach the retina, which is sensitive to light stimulation. These structures are: the lens, the cornea, the aqueous humor and the vitreous humor.

- crystalline: Biconvex lens covered by a transparent membrane. It is located behind the pupil and guides the passage of light to the retina. It also divides the interior of the eye into two compartments containing slightly different fluids: (1) the anterior chamber, filled with aqueous humor, and (2) the posterior chamber, filled with vitreous humor. It may become thinner or thicker because it is attached to the ciliary muscle, which can make it thinner or more curved. These shape changes occur to divert the light rays towards the yellow spot. The lens becomes thicker for viewing near objects, and thinner for viewing distant objects, allowing our eyes to adjust focus to different visual distances. This property of the lens is called visual accommodation. With aging, the lens may lose normal transparency, becoming opaque, what we call cataracts.

- çcornea: transparent portion of the outer tunic (sclera); It is circular in outline and of uniform thickness.

Its surface is lubricated by the tear, secreted by the tear glands and drained into the nasal cavity through a hole in the inner corner of the eye.

- aqueous humorAqueous fluid that lies between the cornea and the lens, filling the anterior chamber of the eye.

- vitreous humor: Most viscous and gelatinous fluid that lies between the lens and the retina, filling the posterior chamber of the eye. Its pressure maintains the spherical eyeball.