VISION B Flashcards
130 million _________ in retina transform light
intensity/color patterns into chemical and electrical signals which trigger activity of retinal cells.
• Information of 130 million photoreceptors is compressed to 1 million highly specialized ________
• 1 million ganglion cells in the retina form the optic nerve and transmit visual information to the ______
Photoreceptors
Ganglion cells
Visual cortex
____ causes blind spot - our brain fills in for it
Optic disc
___________:
-Color specific and high acuity
-Are concentrated in the fovea
Cone photoreceptors
_________
-No Color specificity, low acuity but high sensitivity
-rods are present in the peripheral retina
Rod photoreceptors
Color & high acuity = ___ photoreceptors
Colourless but sensitive = ___ photoreceptors
Cone
Rod
What are the 3 classes of cones ?
S cones
M cones
L cones
_____ cones = short wavelength sensitive
S (short )
____ cones = long wave length sensitive
L (long)
___ cones= middle wavelength sensitive
M (middle)
What are they 3 Color vision deficiencies ?
Monochromats
Dichromats
Trichromats
______- totally colour blind with one cone pathway plus rod pathway
Monochromats
________- a cone photopigment missing thus has only two cone channels
Dichromats
______- all three cone photopigments with one cone photopigment anomolous in having a shifted peak sensitivity
Trichromats
Retinal photoreceptors serve to convert ___energy to ____energy buy virtue of their special cellular structure consisting of an inner cell body and an outer segment of photopigment
Photonics
Chemical
In light, ___ is stimulated , starting a cascade involving transduction and phosphodiesterase (PDE)
Rhodopsin
____ are low resolution while ___ are high resolution
Rods
Cones
_____ cells connect photoreceptors laterally and dampen cells surrounding the centre of maximal receptive stimulation
Horizontal
___ cells are receptive fields for ganglion cells
Cone
_____ cells seRve one based receptive fields
Ganglion
Cone photoreceptors often synapse with 2 different types of ganglion cells : ___ and ____ ganglion cells
On and off centre
________- peripheral cones connect to more horizontal cells which inhibit those neighbouring cells getting weaker stimuli , optimizing acuity
Lateral inhibition
Visual pathway from eye to brain :
___ nerve, ___, ___ tract , ____, _______
Optic nerve
Optic chiasm
Optic tract
Thalamus
Occipital lobe
What Visual acuity is considered legally blind?
20/200
