Question

What is Eye? Describe about the structure of eye?

Answer 1

Heyya!

@ The human eye is an organ which detects light and brings about vision in organisms.

The Shape of the eye is roughly spherical with an average diameter of around 2.3 cm. The outer part of the eye is quite tough and white in colour. This white part of the eye is known as sclera.The transparent, front outer covering of the eye is known as the cornea. Behind the cornea, there is a colored membrane known as the iris. It regulates the amount of light entering the eye. It also gives colour to the eye. In the iris, there is a variable sized, black circular opening known as the pupil. Its size is controlled by the iris. It appears to be black in colour because most of the light entering it is absorbed by the tissues, which are present in the pupil.

The size of the pupil depends on the brightness of light. It opens and closes in order to regulate and control the amount of light entering the eye. When we enter a dimly lit room, it takes the iris some time to expand the pupil to allow more light to enter the eye. For this reason, it takes us a few seconds to clearly see objects in a dimly lit room.

Behind the pupil there is a lens which is thicker at the centre. It is made up of living cells. Two Ciliary muscles hold the lens within the eye-ball. The eye lens being convex in nature converges the light rays’ incident on it. Hence, it focuses the light falling on it on a thin layer of nerve cells called the retina. The retina is made up of a large number of nerve cells. Light falling on these nerve cells stimulate two kinds of sensitive cells known as cones and rods. Rods are sensitive to low light levels. Cones are sensitive to bright light, but they sense colours. Sensation felt by them is transmitted to the brain in the form of electrical signals through the optic nerve. This allows us to see.


Hope it helps!☺️

Answer 2

$\textbf{The Human Eye }$:

Human eye is the most important organ. It is used to see the beautiful nature and the natural phenomena. The human eye works on the refraction of light through a natural convex lens made of transparent living material and enable us to see things around us.

$\textbf{The main parts of human eye are }$:

Cornea, Iris, Pupil, Ciliary muscles, eye lens, retina and optic nerves.

1. $\textbf{Cornea}$:

It is transparent part of eye and allow the light to enter in the eyes, it is the outermost part of the eye.

2. $\textbf{Iris}$:

It is a circular diaphragm having a hole in it's centre. This hole is called $\textbf{pupil}$. The circular diapragm has muscles and coloured pigments. The colour of an eye depends on the colour of these pigments. The function of iris is to control the amount of light entering the eye through the pupil. The pupil becomes small when bright light falls on the eye but it becomes wide when there is dim light.

3. $\textbf{Eye lens }$:

The eye lens is a crystalline double convex lens and made of transparent and flexible tissues. It is behind the pupil and help them by the muscles called ciliary muscles. It focuses the images of objects on the retina of the eye.

4.$\textbf{Ciliary Muscles }$:

These muscles hold the eye lens in position. It controls the focal length of eye lens. When these muscles contracts the focal length of the lens increases when they expands they exerts pressure on the lens and decreases focal length.

5. $\textbf{Retina}$:

It acts as a screen to obtain the image of object. It contains number of cells in the form of rods and cones which are sensitive towards light. These cells convert light energy to into nerve impulses or signals.

6. $\textbf{ Optic Nerves }$:

Optic nerve is found by the nerve fibres coming from the retina. It transfers nerve impulses to the brain.

$\textbf{Working of the eye }$:

When will look towards an object light from the object enters the pupil of the eye and falls on the eyelens. The lens forms a real and inverted image on the retina of the eye. The retina of the eye contains special cells in the shape of rods and cones. These cells convert light energy into electrical signals. These electrical signals carried to the brain through the optic nerves.