How we see ??10 points !!!??

Question

I need some information about "how we see"

i have a science project

i need like information to fill up 7 slides

i searched google but i can't find anything

any useful websites ??

thxxx

10 points for the best answer :D:D

=]]

Answer 1

Vertebrates have eyes with retinas. A retina is a sheet of nerve cells sensitive to light. They line the back of a spherical eyeball and light enters through a round pupil and is focused by a special elastic lens called a cornea. The pupil is surrounded by muscle fibers and can contract and enlarge, depending on the light level.

The nerve cells turn light levels into digital signals which are then interpreted by the brain. The signals travel down the two optic nerves to an area of the brain called the optic lobes. After some preliminary digital processing, the signals travel to an area deeper inside the brain called the optic chiasma. This structure splits the signals so that half of the information from the right eye goes to the left side of the brain. This distributes visual information from both eyes to each side of the brain.

In humans this is very important because brain centers responcible for speech are situated only in one half of the brain. Some stroke victims have damage to the optic chiasma and visual information isn't evenly distributed. If forced to view an object with only one eye, they register it's presence, but cannot name the object.

At the very back of the brain, the preception of sight is generated by three brain centers working simutaneously to decode visual information. The image of the light itself is displayed upside down and backwards on the retina because of the nature of the cornea and pupil. The first task of the visual center is to reformat the data so sight perception reverses what is actually displayed on the retina. The data is then simutaneously analyzed according to outline, color and movement. Again, people suffering strokes provide interesting examples of how these centers affect sight. Damage to the color anaylis section leads to colorblindless. There are three color detectors, red, blue and green. Sometimes only one or two color detectors is damaged, and individuals can see red but can't distinguish between red and green. Individuals with damage to their motion detectors can not see an object unless it is moving. These individuals compensate for stationary objects by constantly shifting their eyes or head around. It is thought the visual systems of some amphibians are similar. Bullfrogs appear to only respond visually to moving objects. Another curious effect of damage to visual centers is "blindsight". A person can not conciously detect the presence of an object in their visual field, but can still react to it. Some even describe objects they can't conciously see in great detail.

The visual center is one of the most intensively studied areas of the brain. If the human body was mapped according to the input to the brain, we would appear to be nothing but an enormous pair of eyes with a tiny body dangling underneith them. Severe damage to the visual centers can cause associated centers to take over these functions. One example is the ease at which blind people can read braile code. The fingertips begin to send tactile information to brain centers which ordinarly process visual information.

Answer 2

We see very much the same way digital camera makes a picture.

The cornea is the lens cover

The Iris is the Aperture

The Eyelid is the shutter

The eye lens is the focusing lens

The Retina is the Sensor

The Optic nerve is the wire to the processor

The Visual cortex is the processor