Optic nerve and visual pathways Flashcards
==]]What do the outer segment of photoreceptors contain?
Discs containing light sensitive photopigment
What are the inner segment of photoreceptors made up of?
Cell body, axon and synaptic terminals
What is the main function of photoreceptors?
Phototransduction – absorb light, send electrical signal
Where are photopigments found?
Lie in discs of outer segments
What are photopigments in rods called?
Rhodopsin
What are photopigments in cones called?
Coneopsin
What are opsins?
Transmembrane proteins which contain the light sensitive molecule retinal
What do different opsin structures mean?
Mean retinal absorbs different wavelengths of light
What causes phototransduction?
Effect of a photon on a rhodopsin molecule
What happens during phototransduction?
Effect of a photon on a rhodopsin molecule
Triggers conformation change to all-trans form
This change triggers changes in the opsin structure
This in turn triggers a cascade within the cell
What is the pathway of signals in the retina?
Photoreceptor → bipolar cell → retinal ganglion cell
What cells modulate signals in the retina?
Horizontal and apocrine cells
What artery supplies the outer 1/3 of the retina?
Choroid (posterior ciliary arteries)
What artery supplies the inner 1/3 of the retina?
Central retinal artery
Which gland is responsible for baseline tear formation?
Accessory lacrimal gland
