Question

When the light is very bright then
A. The iris makes the pupil expand
B. The iris makes the pupil contract
C. The iris and the pupil remains same as they are
D. The iris and the pupil damages

Answer 1

Hint: In human eyes, the tissue which are in front of the eye is called the iris of the eye whereas Pupils are the one which are dark coloured at the opening centres of the eye and iris lies inside the pupil of human eye’s.

Complete answer:
Let us first examine the basic \[7\] parts of the human eye. ‘Cornea’ is the bulging outer part of the eye. This outer layer prevents our eyes from the harmful elements which can damage inner finer parts of the human eye.

‘Sclera’ which is also known as the “whites” of the eye. Sclera is a smooth outer layer white in colour but inside its brown in colour and it is very flexible so that eyeballs can move easily to seek outer objects according to the necessity.

‘Pupil’ which appeared to be a black little dot in the middle of the eye. This black part is a hile through which light enters so that the eye can easily focus on the objects to see.
‘Iris’ is that area of the eye which contains the pigment and it's the reason for the specific colour of the eye.

This iris area surrounds the pupil and uses the muscles to widen or reduce the size of pupil. This allows the pupil to expand and contract according to the need of the amount of light to enter in eyes to form a visible image. Hence, when the light is very bright, the iris contracts the size of the pupil so that only a sufficient amount of light enters and forms a clear visible image.

‘Lens’ which are just behind the pupil. It's a very clear layer which focuses the light that the pupil allows to enter and lenses are held by the ciliary muscle.

‘Retina’ which is present at the back of the eye and is connected through optic nerves which transfers the image formed on the eye to the brain so that the brain can interpret the formed image. Retina is made of small rods and cones arranged in a definite layer which transmits light into chemical and electrical pulses.

‘Choroid’ which lies between the retina and the sclera. The main function of choroid is to provide the sufficient necessary blood supply to the human eye.

Now coming to the question, Human eyes are very sensitive to how much light it allows to enter so that it doesn't get damaged due to very high intense light . Iris controls the size of the pupil. When there is very bright light, the iris allows the pupil to contract so that only a sufficient amount of light enters and an image can be formed on the retina. so the iris of the eye makes the pupil small or reduces its size. The muscles which make the pupil expand and contract are known as dilator pupillae.

Hence the correct option is B.

Note: It should be noted that, in some cases when there is too dim light then iris allows the pupil to expand so that the maximum sufficient light could enter in eye and a clear image could be formed on the retina and so iris is the controller of pupil to allow the light to enter inside the human eye.