What is the human eye?

 

             The human eye is part of the body which reacts to light and has many different other functions. The human has one lens in each eye so the human eye has 2 lenses.  It is made of more than 2 million working parts. The eye has many parts for example, the cornea, lens, iris, retina, optic nerve, and many more. The human eye is one of the most important organs because without the eye humans won't be able to see anything. Without light humans wouldn't be able to see,The retina contains millions of nerve cells called rods and cones it was named after their shape. The cones are used for recognizing color and detail while the rods are responsible for night vision, side vision, and detecting motion. One of the functions of the eye is producing tears. Tears are important because they nourish the surface of the eye and wash away waste on the eye. The eyeballs stay the same size from birth to death. The eye is located in a hollowed eye socket for protection and the eyebrows and eyelashes also protect it. The eyebrows block sweat dripping into the eyes and the eyelashes prevent dirt from going into your eyes. The eye weighs approximately under an ounce and is about an inch across. ⅙ is human eyeball is exposed. The eye is comprised of three coats, encasing three transparent structures.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Internal parts of the human eye:

 

There are many different parts in the internal structure in the human eye and they all have a different function. The parts of the human internal parts are ciliary muscle, iris, lens, cornea, aqueous humor, vitreous humor, sclera, optic nerve, retina, choroid, and blind spot. Each of these parts have different type of function. The ciliary muscle is a ring of smooth muscle in the eye's center layer that controls settlement. The iris controls the size of the pupil which controls the amount of light that goes through the eye. Then there is cornea and it basically is the transparent cover of the eye and it’s main function is to bend light . The aqueous humor is the liquid water substance that is filled in the eye, and the vitreous humor is the gel type of substance which is located at the back of the eye and it helps it support its shape. Sclera is white external layer of the eye that goes about as an intense security from damage, and gives connection to the extraocular muscles that move the eye. The optic nerve is one of the most important parts in the human eye because it transmits what people see to different parts of the body so it could be processed. It is also in charge of sending the picture people recognize to the proper spot for visual handling. Last but not least the retina which is a light-touchy region that gets the picture seen through the eye, just upside down, choroid.

The retina is a sensitive part in the human body located in the part of the eye that cover 65% of its interior surface. There are Photosensitive cells called rods and cones which convert light energy into signals that then are carried to the back of the brain through the optic nerve. There is a small dimple like thing in the middle of the retina called the fovea (aka fovea centralis). The fovea centralis is located in the middle of the eye’s sharpest vision and the most colorful perception. There is a thin layer (that is about 0.5-1 mm thick) of receptors (of light) that covers the inner surface of the choroid.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

External parts of the human eye:

 

External parts of the human eye are are important because they keep the eye safe from anything that tries to enter through it. The eyelids make the eye moist every time we blink and protect our eye from any small thing that can possibly go into our eye (such as sand or any small particles that can harm the eye). The eyelashes are connected to the eyelids and their job is to stop small particles by the hairs attached to the eyelids. The cornea is a part of the external accessories of the eye. It’s job is to direct light/adjust it so that it can go back and hit the retina, and then is when the image is processed. The sclera (or the white part of the eye) is kind of a rough type of structure outside of the eye, it’s purpose is to protect the eye. It is made out of “elastic fiber and collagen”. The pupil and the iris work together, each helping one another so that they can help direct light through them so that they can deliver it to the lens behind them. The iris is made to stretch the pupil out or in so that it can adjust the amount of light that comes into the eye through the pupil. The iris stretches the pupil (outwards) if the person is in a dark place, which make the iris and the pupil work together so that they try to receive even a little bit of light. In really light places, the iris makes the pupil smaller because it is receiving too much light, which makes it become small.