The Retina Flashcards
What are the functions of the retina?
translates light into a biological signal (using photoreceptors). these signals are transmitted to the brain for further visual processing via the optic nerve
What order are bipolar cells
2nd order neurons
what type of potential change to bipolar cells show?
graded change
what are the 2 types of Bipolar cells?
ON and OFF
where do the dendrites of bipolar cells go?
up to photoreceptors
where to the processes of bipolar cells go?
make connections to ganglion cells
what do bipolar cells release?
glutamate
describe ON bipolar cells
respond to reduction in glutamate by becoming excited (depolarise in response to light) They use GPCR glutamate receptor
describe OFF bipolar cells
respond in increase of glutamate by becoming excited and depolarised (in dark)- hyperpolarized in light. Have an ionotropic glutamate receptor.
can bipolar cells produce APs?
no- only graded changes in membrane potential
Where does signal go after bipolar cells?
retinal ganglion cells
what are the 2 types of retinal ganglion cell?
ON and OFF
what are ON RGCs attached to?
ON bipolar cells (and vice versa)
are RGCs excited or inhibited by glutamate?
Excited (therefore excited in dark)
are both ON and OFF signals from RGCs transmitted to brain?
yes
where does each RGC receive information from?
a patch of retina- rather than a single cell
what is the patch of retina the RGCs receive information from called?
receptive field
what’s the purpose of amacrine and horizontal cells?
bring together information from the photoreceptors with the RGCs and bipolar cells
What do horizontal cells do?
(clue’s in name) allow horizontal flow of information in retina (so it’s not just up/down)
what do amacrine cells do?
connect bipolar and RGCs
how do amacrine and horizontal cells affect the RGCs?
allow signalling process to change the RGCs activity in a way more complex than simply how light falls
What is meant by horizontal cells being sign-inverting?
hyperpolarisation becomes depolarisation and vice versa.
what do horizontal cells connect?
neighbouring photoreceptors
what does the sign-inverting do?
dampens down signals
