define human eye.write the name of its parts and working functioning of all
Answers
Explanation:
The eye is an important and one of the most complex sense organ that we humans are endowed with. It helps us in visualizing objects and also helps us in light perception, colour and depth perception. Besides, these sense organs are pretty much similar to cameras and they help us see objects when light coming from outside enters into them. That being said, it is quite interesting to understand the structure and working of a human eye. It helps us also in understanding how a camera also actually functions.
Structure of Human Eye
A human eye is roughly 2.3 cm in diameter and is almost a spherical ball filled with some fluid. It consists of the following parts:
Sclera: It is the outer covering, a protective tough white layer called the sclera (white part of the eye).
Cornea: The front transparent part of the sclera is called cornea. Light enters the eye through the cornea.
Iris: A dark muscular tissue and ring-like structure behind the cornea are known as the iris. The colour of iris actually indicates the colour of the eye. The iris also helps regulate or adjust exposure by adjusting the iris.
Pupil: A small opening in the iris is known as a pupil. Its size is controlled by the help of iris. It controls the amount of light that enters the eye.
Lens: Behind the pupil, there is a transparent structure called a lens. By the action of ciliary muscles, it changes its shape to focus light on the retina. It becomes thinner to focus distant objects and becomes thicker to focus nearby objects.
Retina: It is a light-sensitive layer that consists of numerous nerve cells. It converts images formed by the lens into electrical impulses. These electrical impulses are then transmitted to the brain through optic nerves.
Optic nerves: Optic nerves are of two types. These include cones and rods.
Cones: Cones are the nerve cells that are more sensitive to bright light. They help in detailed central and colour vision.
Rods: Rods are the optic nerve cells that are more sensitive to dim lights. They help in peripheral vision.
At the junction of the optic nerve and retina, there are no sensory nerve cells. So no vision is possible at that point and is known as a blind spot.
Explanation:
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