Human Eye Class 10 Notes
Human Eye Class 10 Notes: In today’s article, there is some information related to the human eye for class 10th students. So that it is easy for you to understand the human eye. We hope that you can get answers to all your questions in this article.
- The human eye is a very valuable and sensitive sensory organ.
- The most sensitive part of the human body is the eye.
- It is located in the eyeball.
- The diameter of the eyeball is 2.3 cm
- To see this world, we need eyes, that’s why the eye is one of the most important parts of the human body.
- The human eye can differentiate between 10 million colors.
- The human eye responds to light for various purposes.
Parts of The Eye
The back curtain of the eye is called the retina. With the help of some cells present in it, light reaches due to which we are able to see. Most eye diseases are caused by defects in the retina. Any problem with the retina reduces the ability to light.
A white protective shield is made around the eye which is opaque called a white plate.
The slightly raised part in the middle of the white septum in front of the eye is transparent. The rays of light refracted from this part enter the eye.
It is an opaque muscle fiber structure at the back of the cornea with a hole in the middle. Its color is mostly black.
The hole in the middle of the iris is called the pupil. Due to the contraction and expansion of the muscles of the iris, the size of pupil keeps getting smaller or bigger as per the requirement. Its size becomes smaller in bright light and its size increases in low light.
Behind the iris is a convex lens made of fibrous jelly-like material. This lens converges the rays of light on the retina. and forms an inverted and real image of the object.
Underneath the white septum of the eye is a membrane-like structure that provides oxygen and nutrition to the retina. At the same time, by absorbing the light coming into the eye, it blocks the reflection of light from the inner walls.
Adjustment ability of the Eye:
- The lens of the human eye can adjust its focal length to see near and far objects, this is called the adjusting power of the eye.
- The focal length of the lens is controlled by the oblique muscles.
When the oblique muscles relax, the eye lens becomes thinner, which increases the focal length of the lens and allows us to see distant objects clearly.
When the oblique muscles contract, the eye lens becomes thicker, which reduces the focal length of the lens and allows us to see close objects clearly.
Visual Impairments :
- In this defect, a person can clearly see objects placed close by but he is not able to see clearly the objects placed far away.
- Due to this defect, the image of a distant object is formed in front of the retina instead of on it.
- The far-off point of a person with such defects does not come to infinity but near the eye.
Causes of Nearsightedness:
(i) Excess curvature of the eye lens.
(ii) Elongation of the eyeball.
long Sigtedness(Hypermetropia )
- In this defect, a person can clearly see distant objects, but he is not able to see closely placed objects clearly.
- Due to this defect, the image of a near object is not formed on the retina but behind it.
As a person ages, the transparency of the eye lens starts losing and its flexibility starts decreasing. Due to this, it starts reflecting the light and the object is not clearly visible. This defect is called a cataract. To correct this defect, the eye lens has to be removed.