Do you know structure of your eye
Eye is the one of the most sensitive sense organ in the human body. Our eye potentially viable us to see this beautiful world. It is consists of a lens, which is the made of the living tissues. How does your eye is work? What are nature, position, relative sizes of the images formed be the lens in the eye?
Structure of human eye-
The human eye is roughly spherical in the shape with the diameter about 2.3 cm. It is situated in the front side of the skull in the bony sockets.It is covered by the eyelids that have eye lashes which prevent dust and other substances entering into the eye. It is consists of the convex lens made of living tissues. Hence, human lenses are living organ contrary to the simple optical lenses. The inner region of the upper eye lid contain Lacrimal glands, that produces secretion which keeps eye surface moist and wash out dirt and other substances. The secretion contain some salts and acts as a antiseptic.
The wall of the eye consists of three layers namely sclera, choroid, retina.
Main parts of the human eye with the functions;-
S.No.
|
Human eye part
|
Function
|
1.
|
Pupil
|
Open and closes in the order to regulate and the control
amount of the light.
|
2.
|
Iris
|
Control the light level similar to the aperture of the
camera.
|
3.
|
Sclera
|
Protective outer coat.
|
4.
|
Cornea
|
Thin membrane which supplies 67% of the eye’s focusing
power.
|
5.
|
Crystalline lens
|
Help to focus the light into the retina.
|
6.
|
Conjunctiva
|
Covers the external surface (visible part) of the eye.
|
7.
|
Aqueous humour
|
Provides power to the cornea.
|
8.
|
Vitreous humour
|
Provides the eye its form and shape.
|
9.
|
Retina
|
Capture the light rays focused by the lens and send
impulses to the brain via optic never.
|
10.
|
Optic never
|
Transmits electric signals to the brain.
|
11.
|
Ciliary muscles
|
Contracts and extends in order to change the lens shape (appearance) for focusing.
|
The white of the eye is known is called sclera. It is tough, opaque tissue that protects the outer layer of the eye. The bulged, transparent front portion of the sclera is called cornea. It is protected by thin, transparent tissue is known as conjuntiva. The middle layer, choroid, contains include blood vessels and looks bluish in colour. It is consists of colour layer of the tissue is called Iris. It is responsible colour of the eye. Pupil is the black, circular hole that is located at the centre of the iris.
The lens is consists of layers of tissue enclosed in a tough capsule. The focus of the lens is adjusted by the ciliary muscles that suspend and hold it. The lens focus the light rays on retina where inverted image of the object is formed.
Retina contains two kinds of cells rods and cones. Rods are sensitive to dim light and cannot differentiate b/w various colours while as cones are sensitive to bright light and can distinguish various colours.
 |
| Rods and Cones |
