What is human eye? Explain the structure and working of human eye?
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Answer:
Human Eye
The Human eye is made up of a thin crystalline lens and has a delicate membrane called retina which is the
screen that is where the image is formed
It has various other parts such as the cornea,iris, pupil, ciliary muscles which help in the functioning of the eye
It has a convex lens embedded inside the lens which forms a real and inverted image on the retina which is recieved and made erect by the brain
Human eye works on the refraction of light of by eye lens made uo of transparent living material and enables us to see things around us.
→ Cornea - The front part of human eye is called Cornea. Cornea is transparent substance whose outer layer is covex in shape. Thus, it refracts most of the light entering into the eye.
→ Iris and Pupil - Iris is coloured diaphragm, mascular and ringed shape tissue located just behind cornea. It expand and contract continuously to adjust size of hole that it consist in it's middle called “Pupil”. Pupil is thus a blank hole that allow light to enter in the eye.
→ Ciliary Muscle and Eye lens - Ciliary muscle is a smooth muscle (involuntary) that contract and expand to change forcal length of “eye lens”. Eye lens is a transparent material made of several proteins and gives final refraction to light.
→ Retina - Retina is background of eye where refracted light gets focused. Retina contains light sensitive cells called “rods and cones”. Rods are sensitive to dim light whike cones are sensitive to colour. They together generate electrical signals.
→ Optic nerve - Optic nerve is connected to Brain and transport the electrical signals from retina. The point where optic nerve and retina meets is called “blind spot”. Here no image is formed due to absence of light sensitive cells.
The image formed at retina is “real” but our Brain inverts it and we get correct image.