Special Senses Vision

Question 1

seeing near objects

Answer 1

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

Question 2

change in refractive power with age

Answer 2

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

Question 3

near response

Answer 3

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

Question 4

seeing far objects

Answer 4

light rays have diverged so they can be focused on retina

relaxation of ciliary m - tension of suspensory ligament - flattening of the lens

Question 5

cornea

Answer 5

1st site of refraction and bends the light the most

FIXED

Question 6

lens

Answer 6

VARIED degree of refraction

Question 7

accommodation

Answer 7

ciliary m
suspensory ligaments
lens

Question 8

photoreceptors

Answer 8

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

Question 9

vertical pathway - cones

Answer 9

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

Question 10

ON center bipolar cells

Answer 10

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

Question 11

OFF center bipolar cells

Answer 11

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

Question 12

ganglion cells

Answer 12

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

Question 13

vertical pathway - rods

Answer 13

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

Question 14

refining signal in the retina

Answer 14

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

Question 15

retina and visual fields

Answer 15

R visual field - L temporal retina and R nasal retina

L visual field - R temporal retina and L nasal retina

Question 16

reconstructing a visual image

Answer 16

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

Question 17

lateral geniculate body

Answer 17

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

Question 18

primary visual cortex (V1)

Answer 18

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

Question 19

V2

Answer 19

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

Question 20

V4

Answer 20

MAJOR JOB complete processing of the color inputs

Question 21

dorsal pathway

Answer 21

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

Question 22

ventral pathway

Answer 22

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