functions of the eye

Lorena Castiglione

The eye

                                                            Parts and functions         

            The cornea is located in the outer part of the eye; it’s a transparent jelly like material that provides protection to the eye.  One function that the cornea does, it bends light to provide focus for the eye, this light than passes through the pupil: a small adjustable opening located in the center of the eye through which light enters.  The pupil is surrounded by the iris, the iris is the colored part of the eye it can be many colors such as green, brown, hazel, blue etc, it is a ring of muscle tissue, and it controls the amount of light that enters the eye.  The brighter the light the eye is exposed to, the smaller the pupil will become.  Located behind the pupil is a lens: which is a transparent structure, it controls the blending of light rays into an image on the retina.

 The retina is a light sensitive inner lining of the eye, it’s black and prevents any light rays that hit it from reflecting, and therefore it changes the image we can see.  The retina is also capable of changing itself depending on the amount of light it receives. The retina contains cell that detect light.  There are 2 subunits in the retina that are responsible for color perception the cones and the rods. The rods are retinal receptors that detect the colors black white and gray.  The rods are necessary for peripheral and twilight vision.  The rods are very sensitive that’s why we they are much more active in lowlight situations.  The cones are considered to be much more complicated and complex than the rods because they are able to distinguish between the different frequencies of light giving rise to color vision.  Located also in the retina is the optic nerve, this is an important nerve because it carries information from the eye to the brain.   When the optic nerve leaves the eye there are no receptor cells, this will than create a blind spot.  The rods and cones have several different tasks they handle inside the retina.  The cones are mostly concentrated in a small circle called fovea, which is the central focal point around which the eye’s cones cluster.  The cones enable us to perceive color; in dim light they become ineffectual.  Rods enable black and white vision; remain sensitive in the dim light

Parts	Function
Cornea	Outermost transparent layer.  Begins focusing process
Pupil	A small adjustable opening to the inner eye through which light enters
Iris	Controls the amount of light that enters the eye, controls the size of the puple
Lens	Focuses image of object on the retina
Retina	Contains cells that detect light
Rods	Twilight vision. Detect black whit and gray.
Cones	Daylight vision. Detect details and give rise to color sensation
Optic nerve	Carries messages from the eye to the brain
Blind spot	Creates blind spot when optic nerve leaves the eye.
Fovea	Central focus of the retina, around which the eye cones cluster.