Physiology of vision

Which part of the eye is responsible for accomodation?

• Cornea

• Lens

• Retina

• Iris

What helps in colour perception

• Ganglion cells

• Cones

• Rods

• Horizontal cells

The blind spot in the eye is due to

• Lack of blood supply

• Presence of extra rods

• Overlapping of images

• Absence of photoreceptors

What is the function of pigment epithelium of retina

• Production of aqueous humor

• Reflects light

• Regenerates photo pigments

• Focuses light

Which layer of retina contains first synapse of visual pathway

• Ganglion cell layer

• Photoreceptor layer

• Inner nuclear layer

• Outer nuclear layer

Inside a dark cave or tunnel what will happen to your pupil size

• Pupil will constrict due to parasympathetic input

• Pupil will dilate due to sympathetic input

• Pupil size remains unchanged

• Controlled by rods

What is the first step of phototransduction

• Opening of Na + channels

• Release of glutamate

• Conversion of 11 cis retinal to all trans retinal by isomerase

• Activation of transducin

Which cells provide lateral inhibition to inhance contrast in retina

• Ganglion cells

• Amacrine cells

• Horizontal cells

• Bipolar cells

What happens to cGMP receptors after light exposure

• They increase

• They decrease

• Levels unchanged

• Convert into AMP

During dark what happens to photoreceptors

• Depolarize and release glutamate

• Hyperpolazie and so remain silent

• Depolarize and silent

• Inactive and do not consume energy