vision Flashcards
the fibrous or corneoscleral tunic contains; what is function?
sclera and cornea; protects eye and attachment for muscles
the vascular or uveal tunic contains what
blood vessles, iris, cilliary body and choroid (contains melanocytes for eye color)
the retinal tunic contains
retina and retinal pigmented epithelium
what are the two parts of the ciliary body
muscular for accommodation and vascular
between cornea and lens
anterior chamber
between lens and iris
posterior chamber
aqueous humor is made in
ciliary body
looking at distant objects ciliary muscles ____ ; the suspensory ligaments ____
relax; contract (flattened lens)
looking at close objects ciliary muscles ____ ; the suspensory ligaments ____
contract; relax (rounded lens)
axial length of eye is too long and light is focused in front of retina
myopia
axial length of the eye is too short; light is focused in back of retina
hyperopia
cones are densely packed in what area
fovea
the RPE (is attached on photoreceptor) can ___ parts of the outer segments of photoreceptor cell as they age
phagocytize
gradual loss of photoreceptors and rods go first (night blindness), the retinal pigmented epithelium deposit in the periphery of the retina
retinitis pigmentosa
____ triggers hyperpolarization in photoreceptors
light
photoreceptors have ____ potentials
graded
the photoreceptor uses ___ to reisomerize all trans retinal to 11-cis retinal
IRBP
the ca 2+ that enters the cGMP gated channel inhibits
guanalyl cyclase, rhodopsin kinase and loss of cyclic GMP binding to its channel (no light)
light induced closure of the cGMP gated channel leads to reduction of ___ and PhR sensitvity to photons is reduced
Ca
vision in dim light, no color, rods only
scotopic
medium bright light; combo of rods and cones
mescopic
vision in bright light; cones primarily (color vision)
photopic
many rods converge onto one ____ cell (rods)
bipolar cell
one cone converges onto one ____ cell
bipolar
more convergence downstream of bipolar cells: many rod bipolar cells converge on a single ____ cell
ganglion
one cone bipolar contacts a single ____ cell
ganglion
in cones visual acuity is much greater because they maintain a one to one relationshoip between
bipolar
no cones or rods in __ ____
optic disk
absorption for rods and cones: long wavelength (L)
red light
absorption for rods and cones: medium wavelength (M)
green
rods repons to light around ____ nm
500
absorption for rods and cones: short wavelength (S)
blue
cones are not evenly distributed within fovea we have ___% L and M but very few S
64
the eye is much less sensitive to ___ light (given less S cones)
blue
what opsin genes are found on X chromosome that can cause color blindness
red and green
2 functional cones (colorblindness is called)
dichromatism
On center bipolar cells: conductance increases in ____; they contain metabotropic glu receptor
light
on center bipolar cells when light increases causes a close in ____ channels and depolarizes the cell due to less ____
cation; glutamate
the off center bipolar cell has increased conductance in ____; the glu channel is coupled to ___ channel (more NT released; hyperpolarization)
dark ;Na
the on center bipolar is ____tropic but the off center is ____tropic
metab; iono
center surround organization requires ____ inhibition by horizontal and amacrine cells
lateral
____ cells inhibit the surrounding photoreceptors
horizontal (Driven by amount of stimulus)
the amacrine cells recieve excitatory inputs from bipolar cells and inhibit the ____ cells
cells
the amacrine and horizontal cells sharpen ____ by being able to focus in on one photoreceptor and inhibiting the others around it
contrast
ganglion cell which has a large cell body and dendritic tree; large center surround fields and signal movement (gross features)
M cells
ganglion cell which has medium cell body and narrower center surround field; they signal fine detail and color
P cells
ganglion cell which has small axons; no center surround fields; respond to contrast bu increasing or decreasing firing rate based off light
w cells
if the receptive field of the ON center ganglion cell is hit in the center it will ____ the cell
depolarize
if the receptive field of the OFF center ganglion cell is hit in the center it will ____ the cell
hyperpolarize
the P cells also have OFF and ON center organization but respond not to color but
specific wavelengths
ON ganglion p cells _____ when color hits center but ____ in OFF cells when color hits center
depolarize, hyperpolarize
ganglion cells project to the optic nerve head which is a __ ____
blind spot
the axons are bundled together to form __ ___
optic nerve
3 main projections from retina: the __ ___ ___ (80%) goes LGN to visual cortex for visual perception
retino-geniculo-striate
3 main projections from retina: goes to pretectum, SCN and accessory optic system. what percentage does this?
5%
structure important for pupillary reflexes
pretectum
region important for circadiam rhythm
suprachiastmatic
the accessory optic system is important for
muscle control of the eyes
3 main projections from retina: the ___ ____ pathway is important for ___ ___ and emcompasses about 15%
retino-tectal
in the LGN of thalamus: 2 ganglion cells project there what are they?
M and P
the M or P cells project to one of the __ layers in the LGN
6
each layer of the LGN is eye and hemi retina specific (either ___ or ___ + right or left)
nasal; temporal
the 2 ventral layers of the LGN are __ specific
M
the 4 dorsal layers of the LGN are __ specific
P
layers 2,3,5 take info from the _____ eye while 1,4,6 gather info from the ____ eye
ipsilateral; contralateral
the meyers loop- _____ retina (superior visual field)
inferior
baums loop- ____ retina (inferior visual field)
superior
the motion pathway (M cells) is
- M ganglion
- LGN
- V1
- V2: thick stripes
- MT
- V5
the color pathway (P cells) is
- parvo ganglion
- LGN(3-6)
- V1 blobs
- V2: thin stripes
- V4
from visual areas 1 and 2 to posterior parietal (where pathway) (important for location)
dorsal pathway
V1 and V2 to inferior temporal (what pathway) ( identification of objects)
ventral pathway
