exam one (eye) Flashcards
over ___ of the human cortex is involved in visual perception
1/3
electromagnetic radiation visible to the eye
light
measurement from trough to peak in a single wave (determines brightness and intensity)
amplitude
distance from peak to peak
wavelength
number of peaks per unit time (determines color)
frequency
radio waves and orange-red colors (hot) have ____ wavelength/energy
low
bouncing of light rays off a surface
reflection
transfer of light energy to a particle or surface
absorption
bending of light rays
refraction
light passes through ____ and then enters the pupil, and is focused by the ____ on the ____
cornea; lens; retina
in visual processing, the ____ is step one
retina
the ___ ____ ____ of the thalamus is the first relay center of light energy
lateral geniculate nucleus
the ___ ___ ___ is responsible for image processing and memory
primary visual cortex
amount of spaced viewed by the retina when the eye is fixated straight ahead
the visual field
what does the overlap of the human eyes allow humans to be good at?
depth perception
what is the function of the cornea?
bends incoming light, by focusing light on retina
changing the shape of the lens is known as
accommodation
the ___ physically changes shape, which allows extra focusing power
lens
___ additional refraction necessary for distant objects
little
greater refraction is needed for focus on ____ objects (this causes a fat lens)
near
people with ____ can’t bring distant objects into clear focus
myopia
people with ____ can’t focus on nearby objects
hyperopia
the ___ ___ ___ controls entry of light
pupillary light reflex
area within the macula that marks the center of the retina and the area of highest visual acuity
fovea
area of retina with relatively few blood vessels
macula
direction of the light message is
photoreceptors to horizontal cells to bipolar cells to amacrine cells to ganglion cells (P.H.B.A.G)
receive input from photoreceptors, project to bipolar cells
horizontal cells
receive input from bipolar cells
amacrine cells
rods and cones have three main regions, what are they?
outer segment, inner segment and synaptic terminal
the outer segment of a rod contains more ___ because of high light sensitivity.
disks
____ are responsible for visual acuity
cones
the fovea is a “pit” where there are only ____ and highest visual ____
cones; acuity
the ratio of cones to ganglion cells is ___ for a clear message
1:1
there is a ____ ratio of rods to cones
higher
the peripheral is more sensitive to ____
light
cones are ____ while rods are not because they focus on light
accurate
what structure converts electromagentic radiation to neural signals
photoreceptors
what are the three main regions of the photreceptor
outer, inner, synaptic terminal
true action potential starts with the ___ cells
ganglion
the outer segment of the photoreceptor contains what
disks with photopigment (rhodopsin in rods)
the inner segment of the photoreceptor contains what
cell body
____ energy activates photopigment (receptor) which stimulates the G protein, which is called what?
light, transducin
what does transducin do
activates effector enzyme (phosphodiesetrase)
The phosphodiesetrase decreases the second messenger which decreases
Na+ and GLU release
in the dark _____ is bound but not activated
rhodopsin
rod outer segments are _____ in the dark, why?
depolarized; elevated cGMP keeps Na+ open which in turn depolarizes the inner segment and increases GLU release
rod outer segments are _____ in the light, what is activated?
hyperpolarized, retinal
mixture of wavelengths produces all colors of the rainbow by activating the three different cones
trichromatic theory
what is the fast small contribution to light adjustment
pupillary reflex
how do your eyes adjust to light (large contribution)
increased cGMP allows Na and Ca channels to open back up (takes 5-10 minutes)
how do your eyes adjust to dark (large contribution)
regeneration of “unbleached” rhodopsin
____ is inactive in the dark
retinal
in the light absorbed light causes a conformational change activating the ____ which “bleaches” it.
opsin
photoreceptors and bipolar cells produce only ____ changes in membrane potentials
graded
retinal non-ganglion cells function
depolarize or hyperpolarize
retinal ganglion cells fucntion
change in frequency of action potentials
ON-center bipolar cell is ____ by light on the receptive fields via direct pathway
depolarized
ON-center bipolar cell is ______ by light on the receptive field surround via indirect pathway
hyperpolarized
when are OFF-center bipolar cells maximally active
when light is only in the surround
bipolar cell receptive fields code for patches and locations of what
light and dark
ON-center on the bipolar cells are ____ signal detectors
light
OFF-center on the bipolar cells are ____ signal detectors
dark
ganglion cell axons that leave by the optic nerve generate action potentials, whats that called?
frequency coding
type of ganglion cell that is large in size, large receptive fields and fast acting
M-type (Magno)
type of ganglion cell that is small in size, small receptive fields, and are wavelength specific
P-type (Parvo)
explanation of color vision that emphasizes the importance of the opposition of colors
opponent-process theory
