Lecture 51 - The visual system Flashcards
what is the:
sclera
encapsulates the eye (laterally and caudally)
what is the:
cornea
part of the sclera that is transparent in front of the eye
what is the:
pupil
entry of light
what is the:
retina
where light is focused (neural)
what is the:
lens
focuses the light
what is the:
ciliary muscle
controls lens thickness
what is the:
iris
controls the amount of light entering
what is the:
choroid
vascular bed surrounding the eye
what is the:
vitreous humor
fills the inside compartment of the eye (between lens and retina)
what is the:
aqueous humor
fills the space between the lens, iris, and cornea
what is the:
anterior chamber
compartment for aqueous humor
give steps 1 - 4 in the perception of light cascade
- light enters through cornea and is refracted
- light passes through the pupil, further refracted by the lens
- an inverted image is projected on to the retina
- photoreceptor cells in the retina respond to light
what is the sensor protein in the photoreceptor
opsin
give steps 5 - 8 in the perception of light cascade
- photoreceptors synapse onto bipolar cells which then synapse to ganglion cells
- signal transmitted through optic nerve to lateral geniculate nucleus
- LGN relays visual signals to the primary visual cortex
- visual broken down into two streams
dorsal stream of vision refers to
spatial information
ventral stream of vision refers to
object-related information
if the ciliary muscles are contracted the pupil is
constricted
what is the 3-component circuit of the retina
photoreceptors –> bipolar cells –> ganglion cells
the inner segment of photoreceptors does what
ATP production and photopigment synthesis
the outer segment of photoreceptors is composed of what
visual pigments in membrane discs
summarize phototransduction in 6 steps
- photon causes isomerization in rhodopsin
- breaks apart G-protein from rhodopsin
- activates cyclic GMP PDE
- PDE hydrolyzes cGMP to be inactive
- close cGMP-gated Na+ channels
- hyperpolarization
T/F: photoreceptors continuously secrete glutamate
TRUE
T/F: glutamate is excitatory in bipolar cells
FALSE - inhibitory
what decreases when photoreceptors are stimulated by light
glutamate production
the decrease in glutamate results in ____ of bipolar cells
depolarization
what are the properties of the rod system
- black and white
- high level of convergence
- high sensitivity to light
- night vision
- motion detectors
what are the properties of the cone system
- color
- low level of convergence
- low sensitivity to light
- day vision
- poor motion detector
do lateral or medial binocular ganglion cells cross
medial
tapetum lucidum
reflective surface that intensifies vision in dim light
tapetal degradation can occur due to
- nutritional induced (Zn deficiency)
- chemical-induced (zinc)
- hereditary (beagles, dilute/white hair)
