vision pt 2 Flashcards
What is ganglion cells?
Action potential generated
What does the ciliary body do?
Produces aqueous humor and controls accommodation to light by changing the shape of the lens
Where is the lens located?
Located just behind iris and held in place by ciliary body
What is the function of the lens?
Focuses light onto the retina, biconvex, transparent, flexible
What is the retina?
Multi-layered sensory tissue that lines the back of the eye
What are cones in the retina used for?
Bright light and color vision (5-6 million)
What are rods in the retina used for?
Peripheral and night vision (125 million)
What is neural layer in the retina?
Continuous to posterior margin of the ciliary body
What are the two layers of retina?
Neural and inner layer
What is inner layer in the retina?
Extension of the brain
What does the optic nerve do?
Transmits electrical impulses from retina to the brain and has optic disc
What is the blind spot?
On retina where optic nerves leads back into the brain, lacks photoceptors, no rods or cone cells
What are the three different photopigments.
Blue, red, green
What is the temporal lobe?
Center for visual learning and recognition by sight
What is the midbrain - limbic sector?
Emotional responses to visual stimuli
What is the midbrain - superior colliculus?
Guides visual attention
What is the cyclic GMP?
In the dark, Na+ channels are held open by a nucleotide
What triggers the release of neurotransmitters?
Inflow of sodium
Na+> K+ ->
cell depolarization
Inhibitory neurotransmitter from photoreceptors to
Glutamate
Synapse between photoreceptor and bipolar cell
Continuous low energy flow through bipolar cell tells your brain you’re in the dark
Rhodopsin formation
Light -> cis -> trans conformation
What is cis?
Bent and lots of energy
What is trans?
Straight and low energy released
Bleaching separation
Cis and trans
What happens when opsin is separated?
Becomes an active enzyme
Process of breaking down cGMP
Activates transducin -> activates phosphodiesterase (enzymes)
What is bipolar cells?
Process info from photoreceptors
What are horizontal cells important for?
Vision
What horizontal and amacrine cells?
Integrate information laterally from many cells
What is macula lutea?
Lateral to the blind spot and mostly cones
What is “filling-in”?
Other eye is compensating for the blind spot
What is fovea centralis?
Has a pit and light directly to photoreceptors to enhance visual acuity
Increase speed
Less dense
Decrease speed
More dense
What is convergence?
Up to 100 rods communicate and cause fuzzy vision
Where is light bent at?
Cornea and twice at lens
What is rhodopsin?
Vitamin A relative and retinal combine with protein (opsins)
Opsin red
560 nm - cones
Opsin blue
420 nm - cones
Opsin green
530 nm - cones
