What is the senses explain their vision , Biology

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What is the Senses explain their Vision ?

Vision :  The human eye consists of structures which evolved together to focus light on a sensitive area called the retina. Light first passes through the cornea, a transparent layer in front of the eyeball. It then traverses the aqueous humor, a watery fluid that nourishes the lens and cornea.

A muscle called the iris, the structure that determines eye color, adjusts the amount of light that enters the pupil, the opening in the iris. Light entering the pupil travels through the lens, a structure shaped like a flattened sphere and composed of transparent protein. The lens is suspended by muscles and ligaments that serve to change its shape to focus images on the retina.

Behind the lens is the vitreous humor, a large chamber of jellylike substance that helps maintain the shape of the eye. The retina is a layer composed of at least 5 million cone cells, reactive to color and responsible for acute vision, and at least 100 million rod cells sensitive to low light levels. Cone cells contain three different types of receptors, each with different pigments absorbing energy in the red, green, and blue wavelengths.

The most sensitive part of the retina, the fovea, contains only cones. Rod cells respond to the visual pigment rhodopsin. They have a low visual acuity and do not respond to color. Under low light conditions, we see predominately in black and white.

 


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