Test 2 - Lecture 4 (Phototransduction)

Question 1

somatosensory system reports

Answer 1

the body’s interactions with its immediate surrounds via touch and feel

Question 2

olfactory system reports

Answer 2

information concerning our surrounds via detection of airborne molecules that arise from carious sources outside the body

Question 3

gustatory system reports

Answer 3

nutritional content and quality of the foods and liquids that we ingest

Question 4

visual system reports

Answer 4

accurately locate and identify distinct objects within our visual space

Question 5

photoreceptors along the retina serve as the

Answer 5

visual receptors (transduce streams of arriving photons into bioelectrical signals for transmission into the brain)

Question 6

intensity of light (illumination)

Answer 6

based upon the number of photons striking a photoreceptor per unit of time (brightness)

Question 7

wavelength

Answer 7

perceived as color

Question 8

vision is based upon the capability

Answer 8

to see distinct objects within our visual space is based upon detecting contrasts in illumination and color

Question 9

visual space

Answer 9

all the outside sources of both emitted and reflected light that enters the eye

Question 10

visual field

Answer 10

region of visual space that projects light upon the retinal surface of EACH eye

Question 11

extensive overlap between the L and R monocular visual fields forms

Answer 11

binocular visual field (roughly the central 2/3 of the visual space)

Question 12

outside the binocular visual field are the L and R

Answer 12

monocular crescents (lateral portions of the visual space seen by just the L or R eye)

Question 13

retinotopic map

Answer 13

transmit sensory information from the retina into the primary visual cortex (basis for brain to perceive where objects located to our body)

Question 14

actual projection of the visual field upon the surface of the retina is

Answer 14

inverted and left/right reversed

Question 15

temporal visual field project upon the

Answer 15

nasal retina

Question 16

nasal visual field project upon the

Answer 16

temporal retina

Question 17

superior visual field projects upon the

Answer 17

inferior retina

Question 18

inferior visual field projects upon the

Answer 18

superior retina

Question 19

retina cell column order

Answer 19

photoreceptors (rods and cones), bipolar cells, and ganglion cells

Question 20

horizontal cells

Answer 20

interneurons, which modulate transmission from the photoreceptor to the bipolar cell

Question 21

bipolar cells

Answer 21

serve as relay between the photoreceptor and the ganglion cell

Question 22

ganglion cells

Answer 22

the projection neurons that generate signals for transmission into the brain via optic nerve

Question 23

rods

Answer 23

high sensitivity, night (scotopic) vision; are monochromatic (no color)

Question 24

cones

Answer 24

low sensitivity, providing day (photopic) vision; are chromatic

Question 25

structure of the retna

Answer 25

pigment epithelium, photoreceptor layer, neural network layer, ganglion cell layer

Question 26

muller cells

Answer 26

function as channel for light photons to reach photoreceptors

Question 27

ganglion cells are always stimulated by the NT released from the

Answer 27

bipolar cell

Question 28

low intensity light... cGMP is plentiful and Na channels are

Answer 28

open

Question 29

high intensity light, cGMP is reduced and Na channels are

Answer 29

closed

Question 30

photoreceptor cells ______ as light intensity is reduced

Answer 30

depolarize

Question 31

photoreceptor cells ________ as light intensity is amplified

Answer 31

hyperpolarize

Question 32

dark (no photons): cations Na and Ca channels are

Answer 32

open

Question 33

bright light: cations Na and Ca channels are

Answer 33

closed

Question 34

photoreceptor adaptation that reverses the light-induced reduction in cGMP

Answer 34

- cGMP must be regenerated within the photoreceptor | - Ca inhibits cGMP regeneration

Question 35

glutamate release is dependent upon the photoreceptor membrane potential: depolarized vs hyperpolarized

Answer 35

depolarized: increased NT release hyperpolarized: decreased NT release

Question 36

NT release is graded; ______ relationship with absorbed light intensity

Answer 36

inverse

Question 37

glutamate released from bipolar cell ALWAYS triggers

Answer 37

EPSP in ganglion cell

Question 38

glutamate released from photoreceptor may trigger

Answer 38

either EPSP or IPSP on bipolar cell

Question 39

off retinal column

Answer 39

absence of light

Question 40

on retinal column

Answer 40

presence of light

Question 41

off bipolar cells have

Answer 41

excitatory glutamate receports

Question 42

on bipolar cells have

Answer 42

inhibitory glutamate receptor

Question 43

dark conditions: off bipolar vs on bipolar

Answer 43

off bipolar - depolarize (more active) | on - hyperpolarize (less active)

Question 44

light conditions: off bipolar vs on bipolar

Answer 44

off bipolar - hyperpolarize (less active) | on bipolar - depolarize (more active)

Question 45

horizontal cells function as

Answer 45

inhibitory interneurons (GABA NT)

Question 46

signaling from the central photoreceptors to the bipolar cell is determine by two opposing influences

Answer 46

- illumination of the central photoreceptors | - signaling form the horizontal cells

Question 47

center only light stimulation: GABA

Answer 47

no change in GABA release from horizontal cells

Question 48

extend illumination to now include the surround: GABA

Answer 48

reduced stimulation of horizontal cells = reduced GABA release to center receptors (causes depolarization = increasing NT of center)