Construction of an Eye


 
 
Concept Explanation
 

Construction of an Eye

Construction Of Eye:

The eye performs three functions:

1. It makes adjustments to admit appropriate amount of light.

2. It bends the rays of light to form a sharp image,

3. It collects and sends information about the image to the brain for further 'processing.

Eye allow to learn more about the surrounding world that we do with any of the other four senses. Different parts of the eye perform these functions. The figure shows schematically the basic components of the human eye.

The eye has a roughly spherical shape. The different parts of the eye are contained within the spherical eyeball, which is about 2.5 cm in diameter. An opaque, white, protective membrane called the sclera covers most of the outer part of the eyeball and is known as white of the eye. A small portion at the front of the eyeball bulges out. A transparent protective membrane called the cornea covers this portion.

   

Behind the cornea the major structures of the eye consists of 

Iris: It controls the amount of light entering the eye by changing the size of the pupil.

Pupil  is the hole int he middle of the iris through which light enters the eye.

Retina: It is a light sensitive screen inside the eye on which the image is formed. It containstwo kinds of cells

1. Rod cells: They are sensitive to dim light.

2.Cone cells: They are sensitive to bright light. They can sense the different colours.

Optical nerves :These nerves which take the image to the brain in the form of electrical signals.

Sample Questions
(More Questions for each concept available in Login)
Question : 1

Identify which of the following are the functions of eye.

Right Option : D
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Question : 2

Refractive power of cornea in human beings is appoximately _______________.

Right Option : C
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Question : 3

The outer layer of the eye is called _______________ .

 

Right Option : B
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