Eyes Flashcards
What is phototransduction?
Catching light
What do photoreceptor cells do?
Transduce light into receptor potentials
What are the two types of photoreceptors called in the vertebrate retina?
Rod and cone cells
What are rod cells sensitive to?
Broad colour sensitivity and sensitive to low light levels
What are cone cells sensitive to?
Sensitive to particular colours and good for detail in bright light
What are the sodium channels in the outer cell membrane held open by in the dark?
cGMP
What are the photopigments called and what are the two parts?
Rhodopsins
Opsin (a protein)
11-cis-retinal (light absorbing aldehyde)
What does absorption of light do to 11-vis-retinal?
Changes it’s shape to form all-trans-retinal
What do vertebrate photoreceptor cells do in response to light?
They hyperpolarise (become more negative) compared to most cells that depolarise
What is the strength of a light stimulus coded as?
Amplitude of receptor potential
How many layers of neurons are in the retina and where are photoreceptors
5
At the back
What do the bipolar cells do?
Connect photoreceptors with retinal ganglion cells
What do horizontal cells do?
Modify signals passing from photoreceptors to bipolar cells
What do amacrine cells do?
Modify signals passing from bipolar to retinal ganglion cells
What do the retinal ganglion cells do?
They’re at the front and have axons that join the optic nerve and send spikes to the brain
