netter33

Visu.il System: Receptors

NEUROPHYSIOLOGY

A. Eyeball

B. Section

Inner limiting

Ihrough retina

membranę Axons at surface

Susprnson,'

Cornea

of retina passing

optic nerve,

chiasm, and tract

geniculate body

Anterior Posterior chamber chamber

Ora conlaining serrata agueous humor

Vitreous humor

T Retina Choroid

Ganglion celi MOller celi (supporting glial celi)

Amacrine celi Bipolar celi Horizontal celi Rod Cone

Pigment cells of choroid

Figurę 2.32 Vi$ual Receptors_

The rods and cones of the retina transduce light inlo electrical sig-nals. As illustrated for the rod. light is absorbed by rhodopsin, and through the second messenger cGMP (not shown). Na" channels in the membranę close and the celi hyperpolarizes. Thus, in the dark the celi is depolarized, but it is hyperpolarized in the light. This electrical response to light is distinct from other receptor responses, in which the response to a stimulus results in a depolarization of the receptor celi membranę.