8.5

Question 1

State the order of neurons involved in responding to light and communicating to the brain, starting with the rod cells

Answer 1

Rod cells -> bipolar neurons -> ganglion cells -> optic nerve

Question 2

Describe the response of rod cells to darkness

Answer 2

Rhodopsin is unchanged, sodium channels in the middle of rod cell open, causing flow of depolarisation to synapse, glutamate (an inhibitory neurotransmitter) to be produced, released and diffused across the synapse and prevent an action potential in the bipolar cell

Question 3

Describe the response of rod cells to light

Answer 3

Rhodopsin is photosensitive and breaks down to retinal and opsin, causing sodium channels in the rod to close, the rod is hyper-polarised so no action potential is present, no glutamate is released and receptors on the bipolar cell are unbinded so an action potential forms

Question 4

Explain why visual acuity (how sharp the image is) is better with colour vision than with our grayscale vision