Special Senses Vision Flashcards Preview

Nero Exam #2 > Special Senses Vision > Flashcards

Flashcards in Special Senses Vision Deck (22):
1

seeing near objects

light rays still diverging so require more refraction to focus light on retina
contraction of ciliary m - relaxation of suspensory lig. - rounding of lens

2

change in refractive power with age

young kids - 20 diopters
young adults - 10 diopters
50's - 1 diopter

3

near response

contraction of ciliary m
convergence of the eyes to the point of focus
constriction of pupil

4

seeing far objects

light rays have diverged so they can be focused on retina
relaxation of ciliary m - tension of suspensory ligament - flattening of the lens

5

cornea

1st site of refraction and bends the light the most
FIXED

6

lens

VARIED degree of refraction

7

accommodation

ciliary m
suspensory ligaments
lens

8

photoreceptors

constant release of glutamate
dark (no stimulation) release of glutamate is high
photon activates and release of glutamate decreases

9

vertical pathway - cones

photoreceptor struck by photon of light
decreases NT (glutamate) release onto a bipolar cell

10

ON center bipolar cells

activation leads to depolarization of bipolar cell
METABOTROPIC R activated NT release causes decrease in cation influx
dark - hyperpolarization
light - release of glutamate from the photoreceptor decreases so the cation current increase and the ON center is depolarized

11

OFF center bipolar cells

activation leads to hyperpolarization
AMPA R activated NT release causes an increase in cation influx
dark - depolarized
light - glutamate release from the photoreceptor decreases the AMPA R is NOT activated and OFF center is hyper polarized

12

ganglion cells

axons become fibers on the optic n
1st place AP can be generated
glutamate is NT

13

vertical pathway - rods

many rods
converge on the ON center bipolar cells
synapse on A11 amacrine cell
synapse on cone on center bipolar cell
activates ganglion cell

14

refining signal in the retina

role of ON/Off center cells is the ability to detect edges so they sharpen our vision
ON - where something is
OFF - where it ends
amacrine and horizontal cells - inhibitory signals that modify the activity of neighboring photoreceptors, bipolar cells, or ganglion cells

15

retina and visual fields

R visual field - L temporal retina and R nasal retina
L visual field - R temporal retina and L nasal retina

16

reconstructing a visual image

optic chiasma from NASAL RETINA will cross and joint the axons from temporal retina
R visual field seen in L side of the brain

17

lateral geniculate body

control motion of the eye so they converge on the desired point of interest
control focusing so that the image we are interested in is the best focus possible
identify major elements w/in visual image
identify motion w/in our visual image

18

primary visual cortex (V1)

layers 1,2,3 - networking to other parts of cortex
layer 4 - info from LGN
layers 5 & 6 - send info back to LGN
each column does a different job
input from photoreceptors in the macula (greatest density of R)
MAJOR JOB - identify the edges contours of the components in our visual image
color vision

19

V2

MAJOR JOB identify disparities in the visual images presented by the two eyes
used for depth perception

20

V4

MAJOR JOB complete processing of the color inputs

21

dorsal pathway

leaving occipital cortex relays visual information to the motor cortices and enables us to complete motor acts base on visual input

22

ventral pathway

relays visual info to areas of the brain involved in higher processing of sensory inputs