Humans are equipped
with sensory devices, there are sense of hearing, sense of touch,sense
of taste, sense of smell and sense of sight. Senses function is capture changes of around us. Every devices sense have special function, its mean they can only catch types of stimulus.
Eyes are a sense of sight that is sensitive of light stimulus. How does vision process so that we can see object?. Explanation of the process of human sight is the object that being look at somehow altered the "medium" (as known as air) between the object and the viewer's eye. This alteration of the medium is propagate to the eye, allowing the object to be seen.
First, reflection light of
object is entering the eye through the transparent cornea that focuses light
into the eye. Behind the cornea is a watery fluid called the aqueous humor. Then,
light pass on aqueous humor and pupil, which is the opening in the center of
the iris. Iris controls the pupil size so that the incoming light can be set. Then,
light transmit to the lens. Next, eyepiece accommodate so that the shadow falls
exactly on back parts of the retina, fovea, which has more cone cells than in other
parts. Retina consist of photoreceptors that composed of stem cells and cone
cells that have function to receive the light from the lens through aqueous
vitreous. The cone cells are sensitive to strong light and colors while stem
cells are sensitive to weak light and colorless. If the light is focused on the
fovea, so that we will see clearly. The farther from the fovea the fewer the
number of cone cells. Next, photoreceptors receive stimulations or impulses and
pass on them to front part of retina by through bipolar cells and nerve cells and pass by to nerve fibers then the optic nerve to
the brain and arrive in occipital lobe. Finally, we can see and realize what we
see.
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