visual system exam 2 Flashcards
dumbed down version of how light gets converted into electrical signals
transduction: opsin(the transmembrane protein) absorbs light and the retinal changes conformation. this activates a G protein, which downstream causes the closure of Na channels. closing the channels causes hyperpolarization. this reduces the action potential, causing inhibition of the release of glutamate.
outer plexiform layer
synapses between photoreceptors and bipolar cells
rods vs cones in vision
rods are night vision, cones are central vision, color and detail
in the retinogeniculostriate system, where do they synapse
in the thalamus in the lateral geniculate nucleus
what is the retino-tactal tract?
the unconscious perception of light. just light for reflexes.
where does the retinotactical system project ?
midbrain in two spots. rostral colliculus and the pretectal nucleus.
how does PLR work
light is converted to electrical signal, goes to pretectal n in midbrain (unconscious), projects onto the PS nucleus of CN III, then to eye
dazzle reflex?
light to chemical signal, pretectal nucleus in midbrain, facial motor nucleus, eyes close
menace (conscious perception)
stimulus of object, retino-geniculate-striate pathwy to lateral geniculate nucleus in thalamus, interneurons to primary motor cortex, corticobulbar pathway to facial nucleus, eyes close
vestibulo-ocular refex
hair cells detect movement, send signal to CN VIII, neurons in vestibular nuclei project to CN III, IV, VI. extraocular muscles constrict on the opposite side that the head is moving so you can focus on an object while your head is moving away
lesion in the optic nerve
sight lost in the same side eye
lesion in the optic chiasm
periheral vision lost in both eyes in carnivores and all vision lost in herbivores because there is no overlap of visual fields so they all cross
