Question

Explain the function of the following parts of the human eye:-
1) Sclera
2) Cornea
3) Iris
4) Pupil
5) Crystalline lens
6) Aqueous Humor
7) Vitreous Humor
8) Ciliary Muscles
9) Retina
10) Optic Nerve

Answer 1

1) The sclera is the part of the eye commonly known as the “white.” It forms the supporting wall of the eyeball and is continuous with the clear cornea. The sclera is covered by the conjunctiva, a clear mucous membrane that helps lubricate the eye. It is thickest in the area surrounding the optic nerve.
2) The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
3) The iris is the coloured circle surrounding the pupil. It changes the size of the pupil and allows different amounts of light to enter the eye.
4) The pupil is a hole located in the centre of the iris of the eye that allows light to strike the retina.
5) The crystalline lens is a transparent, biconvex structure whose functions are to maintain its own clarity and to refract light to provide accommodation.
6) The aqueous humour is a transparent, watery fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary epithelium, a structure supporting the lens.
7) The vitreous humour comprises a large portion of the eyeball. It is a clear gel-like substance that occupies the space behind the lens and in front of the retina at the back of the eye.
8) The circular ciliary muscle fibres affect zonular fibres in the eye (fibres that suspend the lens in position during accommodation), enabling changes in lens shape for light focusing.
9) The retina is a thin layer of tissue that lines the back of the eye on the inside. It is located near the optic nerve.
10) The optic nerve from each eye carries impulses to the brain, where visual information is interpreted.