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प्रश्न
Write short notes on the following: Retina
उत्तर
Retina
Retina is the innermost layer. It contains three layers of cells – inner ganglion cells, middle bipolar cells, and outermost photoreceptor cells. The receptor cells present in the retina are of two types – rod cells and cone cells.
(i) Rod cells –The rods contain rhodopsin pigment (visual purple), which is highly sensitive to dim light. It is responsible for twilight vision.
(ii) Cone cells –The cones contain iodopsin pigment (visual violet) and are highly sensitive to high intensity light. They are responsible for daylight and colour visions.
The innermost ganglionic cells give rise to optic nerve fibre that forms optic nerve in each eye and is connected with the brain. In this region, the photoreceptor cells are absent. Hence, it is known as the blind spot. At the posterior part, lateral to blind spot, there is a pigmented spot called macula lutea. This spot has a shallow depression at its middle known as fovea. Fovea has only cone cells. They are devoid of rod cells. Hence, it is the place of most distinct vision.
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संबंधित प्रश्न
Write the function of the following part of the human eye:- iris
Draw labelled diagrams of the following: Eye
The region of the vertebrate eye, where the optic nerve passes out of the retina, is called the
(a) fovea
(b) iris
(c) blind spot
(d) optic chaisma
What is the range of vision of a normal human eye?
What changes take place in the shape of eye-lens:
when the eye is focused on a near object?
How does the eye change in order to focus on near or distant objects?
(a) The lens moves in or out
(b) The retina moves in or out
(c) The lens becomes thicker or thinner
(d) The pupil gets larger or smaller
fill in the following blank with suitable word:
A person is short-sighted if his eyeball is too............Spectacles with a .............lens are needed. A person is long-sighted if his eyeball is too............Spectacles with a ................lens are needed. These focus light rays exactly on to the..........
Answer the following question.
Write the structure of eye lens and state the role of ciliary muscles in the human eye.
Name the following:
Fluid present in the posterior chamber of the eye.
State the Function:
Conjunctiva
Choose the Odd One Out:
Complete the following sentence with appropriate Word
The part of the human eye where rod cells and cone cells are located is the:
Complete the following sentence with appropriate Word
The photoreceptor cells of the retina sensitive to colour are:
For a normal human eye the near point is at _______.
Write an Explanation.
Power of accommodation
Which cells of the retina enable us to see coloured objects around us?
Vitreous humour is present between ______.
Assertion (A): Rods and Cones are photoreceptors in the sclera of eyeball.
Reason (R): Rods are sensitive to dim light.
Where is the following located?
Yellow spot
With reference to human eye answer the question that follow:
Name the part of the eye associated with keeping the lens moist and protecting it from physical shock.
