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The Human Senses

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The Human Senses
Senses

What are the human senses and how do they work?
The human senses are faculties by which the human body perceives external stimulation. Humans have senses to help them experience the world around them. The five main senses are sight, hearing, taste, smell and touch. Each of these five senses consists of organs with a specialized structure that has receptors for specific stimulation. These receptors are linked to the nervous system and therefore the brain.

Sight
Sight is the sense by which humans have the capability to detect images and distinguish objects. According to Zamora, A (n.d.), sight is probably the most developed sense in humans, followed by hearing.

In the front of the eye, a transparent structure called the cornea can be found. The cornea helps to focus incoming light. Behind the cornea lays the iris, which is a colored ring-shaped membrane. The space behind between the cornea and the iris is filled with a fluid called the aqueous humor.
Within the iris there is an opening called the pupil, which can adjust its size depending on the amount of light entering the eye.
Behind the pupil is structure containing a lens and muscles. When the muscles relax, the lens flattens, allowing the eye to see object far away. In contrary, to see closer objects, the muscle contracts, which thickens the lens.
The eye itself is made up out of three tissue layers. The outer layer is called the sclera, which gives the eye its white color. The middle layer, called the choroid, contains blood vessels that supply the inner eye with nutrients and oxygen. Lastly, the inner layer of the eye is called the retina. This layer is filled with light sensitive cells that can be divided into two main varieties: rods and cones. The rods are for good vision in poor light, while cones are mainly for detection of color or detail.
When light comes through the pupil and strikes either the rods or the cones, the light is converted into an electric signal that is

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