neuro day 2 exam review- ch 7 vision

what role does phosphodiesterase play in visual transduction?

lowers level of cycling GMP=sodium channels will close (phosphodiesterase activates in light)

know what happens in visual transduction/steps of this

(that ch. 7 slideshow has this all over i think.. idk where)

what takes longer to adjust to, going from dark to light or going from light to dark?

going from light to dark takes longer to adjust- light adaptation takes secs but dark adaptation occurs over several mins (needs time to regenerate photopigments)

what role do calcium (Ca2+) ions play in visual transduction?

acts in negative feedback, keeps from getting too high or too low

what role do calcium (Ca2+) ions play in the dark cycle?

in the dark, they inhibit guanylyl cyclase and stimulate phosphodiesterase (~breaks down cGMP)

during increasing light intensity, does the electrical potential become increasingly hyperpolarized?

yes! as light becomes brighter and brighter, its electrical potential/the cell becomes more and more hyperpolarized (can see this on slide 25)

does increasing hyperpolarization lead to a decrease in neurotransmitter?

yes! (again slide 25)

does phototransduction occur in the optic disc?

no! there’s no photoreceptors in the optic disc AKA the blind spot

different bipolar cells respond differently to changes in glutamate? (t or f)

TRUE (the slide he said don’t worry too much, u just needa know this point)

lateral inhibition genertaed contrast at the edges of regions or areas being looked at? (t or f)

TRUE