sclera 

blind spot 

fovea

choroid

ommatidium 

The enzyme Guanylate cyclase is able to produce more cGMP

The G protein, Transducin, is able to recover from light-induced inhibition

The ion channels allow in more Ca⁺⁺ into the cell

Rhodopsin recovers sensitivity from light-induced bleaching

The ion channels increase the standing current flow to repolarize the cell

consists of ON centre cells where the centre is selective for Blue light and OFF centre cells where the centre is selective for Yellow light.

consists of cells receiving most of their input from cones at the optic disk.

consists only of ON centre cells where the centre is selective for Blue or Yellow light.

 consists of cells receiving inputs only from rods.

consists of ON centre and OFF centre cells where the centre is selective for Blue or Yellow light.

Is useful in allowing better detection of light in daylight conditions

Allows better detection of wavelength-sensitivity differences

Is useful in allowing better detection of sources of low light levels

Allows better detection of flickering light

Allows better discrimination of colour

their response is slow and longer-lasting.

they respond only to axial light rays.

they respond only at night.

they are present only at the fovea.

their response is fast and is over quickly.

are never inhibited by light anywhere across the retina.

are excited by light in the RF surround and inhibited by light in the RF centre.

are excited by input from cones and inhibited by input from rods.

are excited by light in the RF centre and in the RF surround.

are excited by light in the RF centre and inhibited by light in the RF surround.

is greatest at the fovea where visual acuity is highest.

is smallest at the optic disk where there are few rod photoreceptors.

reflects the number of cyclic GMP molecules broken down by light.

reflects the amount of convergence from photoreceptors to RGCs.

is affected by the power of accommodation which, in turn, decreases with age.