Special Senses Vision - 4/11 Karius Flashcards
What is the job of the lens?
Adds a variable degree of refraction
What does accommodation require?
Ciliary muscle
Suspensory ligaments (connect ciliary to the lens)
Lens itself
What happens to the tension on the suspensory ligaments as the ciliary muscle contracts?
What happens to the lens?
Curvature of lens? Refractive power of lens?
Tension released, ligaments become slack
Lens gets rounder
Increased curvature and refractive power of the lens
What happens to the lens in FAR vision?
Ciliary muscle relaxes
Suspensory ligament tenses
Lens becomes flat
DEC curvature and DEC refractive power
What does the near response include?
Contraction of ciliary muscles
Convergence of the eyes to the point of focus
Constriction of the pupil
What composes the vertical pathway of the retina?
Photo receptor
Bipolar cell
Ganglion cell
When is it dark (no stimulation) what is the release of glutamate like?
High
What happens if a photo receptor activates an ON center bipolar cell?
Metabotropic receptor activated
nt released causes DEC Na and Ca into bipolar cell
Activation of a photoreceptor in the center of an ON-center bipolar cell, what happens?
OFF-center?
Depolarization of bipolar cell
Hyperpolarization
What is activated when a photoreceptor activates an OFF center bipolar cell?
Nt release causes an increase or decrease in cation influx?
AMPA receptor activated
Increase
How is the ganglion cell excited?
What do the ganglion cell axons become?
What is special about ganglion cells?
Bipolar cell releases glutamate
Fibers on the optic nerve
APs
Where do rods converge?
Then synapses where?
What next?
Finally activates what?
On 1 ON-center bipolar cell
A11 amacrine cell
Cone ON-center bipolar cell
Ganglion cell
What is the main fx of on and off center cells?
On-center cell specifically?
Off-center cell specifically?
Increases ability to detect edges and sharpen our vision
On-tell us where something IS
Off-tell us where it ENDS
What in the eye is activated by light coming from the right visual field?
Left temporal retina
Right nasal retina
What part of the brain is responsible for reconstructing the visual image?
What exists there?
Lateral geniculate body
ON and OFF-center cells
Functions of lateral geniculate body?
Control motions of the eyes
Control focusing
Identify major elements within our visual image
Identify motion
From the lateral geniculate body where does the information go to?
Primary visual cortex(V1)
What do layers 1, 2, and 3 allow?
Networking between V1 and other parts of the cortex
What does layer 4 of the primary visual cortex do?
Receives inputs from LGN
Axons synapse here
What do layers 5 and 6 of the primary visual cortex do?
Send information BACK to the LGN
Where do the columns in V1 receive input from?
What kind?
Photoreceptors in the macula
Lots of cones
What is the major job of V1?
Identify the edges or contours of the visual image
What is the major job of V2?
Very important for what?
Identify disparities in the visual images presented by 2 eyes
Depth perception
Where does color vision occur?
V1
What is the major job of V4?
Complete processing of color inputs
What pathway is used to enable us to complete motor acts based on visual input?
Dorsal visual pathway
What pathway is used to accomplish higher order functions including naming and copying objects?
Ventral visual pathway
Where are similar or related objects are all coded for in localized regions of what?
Temporal lobe
Where is the 1st site in the eye where refraction occurs?
How much responsibility does it have for bending the light?
Cornea
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