The human eye and it's parts class 8 CBSE topic wise note

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ the eye allows vision. Rod and cone cells in the retina allows conscious light perception and vision including colour differentiation and the perception of depth. 

 Retina:

Retina is a light sensitive tissue lining the inner surface of the eye.

Rod cell:

Rods are photoreceptor cells in the retina of the eye that can function in less intense light. They are of cylindrical shape and are almost responsible for night vision.

 Cone cells :

Cone cells are photoreceptors cells in the retina of the eye that are rêsponsible for colourvision.

 Cornea :

 The cornea is the transparent front part of the eye that covers the iris, pupil and anterior chamber.

 Pupil:

The pupil is a hole located in the centre of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside eye.

 Iris:

 The iris is thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.

 Lens:

The crystalline lens is a transparent, biconvex structure in the eye-that along with the cornea helps to refract light to be focused on the retina.

Aqueous humour:
The aqueous humour is a clear, gelatinous fluid similar to plasma but containing low protein concentration. It is located in the space between the lens and the cornea.

 Vitreous humour:

The vitreous humour is the transparent, colourless, gelatinous mass that fills the space between the lens of the eye and the retina lining the back of the eye.

 Optic nerve:

 The light sensitive nerve cells carry the impression to the brain by the means of the optic nerve.

FACT FILE:- The human eye can distinguish about 10 million colcurs.
The optic nerve, also called cranial nerve.