Electrical Activity of Retinal Cells
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12.6.08
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Ganglion cells and amacrine cells are only neurons that produce AP.
In dark, photoreceptors release inhibitory NT that hyperpolarizes bipolar neurons.
Light inhibits release of inhibitory NT.
Dark current:
Rods and cones contain many Na+ channels that are open in the dark.
Causes slight membrane depolarization in dark.
Na+ channels rapidly close in response to light.
cGMP required to keep the Na+ channels open.
Opsin dissociation causes the alpha subunits of G-proteins to dissociate.
G-protein subunits bind and activate phosphodiesterase, converting cGMP to GMP.
Na+ channels close when cGMP converted to GMP.
Category: Ophthalmology Notes
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