Neuro Fns Lect #34

Front 1

These photoreceptors detect low light levels at the expense of visual acuity and do not discriminate among colors (cones or rods)?

Back 1

Rods

Front 2

These photoreceptors are specialized for visual acuity and color vision at the expense of sensitivity to light (rods or cones)?

Back 2

Cones

Front 3

These photoreceptors are most concentrated in the fovea (rods or cones)?

Back 3

Cones

Front 4

This is the photopigment found in rods?

Back 4

Rhodopsin

Front 5

Cones have high or low acuity ?

Back 5

High

Front 6

Which photoreceptor has fast adaptation?

Back 6

Cones

Front 7

The absolute threshold is found in the (scotopic, mesopic, photopic) luminance scale?

Back 7

Scotopic

Front 8

Rod saturation begins between which two levels of luminance (scotopic and mesopic; or mesopic and photopic)?

Back 8

Mesopic and photopic

Front 9

Which level of luminance is the best acuity found in (scotopic, mesopic, photopic)?

Back 9

Photopic

Front 10

Which receptor is activated in the scotopic range of luminance (rods, cones, both, neither)?

Back 10

Rods

Front 11

Which receptor is activated in the mesopic range of luminance (rods, cones, both, neither)?

Back 11

Both

Front 12

Which receptor is activated in the photopic range of luminance (rods, cones, both, neither)?

Back 12

Cones

Front 13

Stimulation of photoreceptors by their stimulus produces (hyperpolarization, depolarization, both, neither)?

Back 13

Hyperpolarization

Front 14

What kind of sodium gated channels are located on the outer segment of photoreceptors?

Back 14

cGMP-Gated Na Channels

Front 15

cGMP is high during (light, absence of light)?

Back 15

Absence of light

Front 16

The photorecetor during darkness is (depolarized, hyperpolarized, both, neither)?

Back 16

Depolarized (cGMP is high > Channels are open)

Front 17

What transmitter is released during depolarization of photoreceptors?

Back 17

Glutamate

Front 18

What happens to cGMP when light hits the outer segment of photoreceptors?

Back 18

Hydrolysis of cGMP by an activated phsophodiesterase

Front 19

What decreases the amount of transmitter released at the synaptic terminal in photoreceptors (hyperpolarization or depolarization)?

Back 19

Hyperpolarization

Front 20

Is the transmitter released from the phtoreceptor usually excitatory or inhibitory?

Back 20

Inhibitory

Front 21

Which system has greater convergence (rods or cones)?

Back 21

Rods (50 rods converge onto on bipolar cell)

Front 22

What two things contribute to the rods greater light sensitivity?

Back 22

Higher levels of pigment and Amplification

Front 23

These cells modulate interactions between photoreceptor and bipolar cells?

Back 23

Horizontal Cells

Front 24

What are the only retinal cell types to produce action potentials, versus the others, which communicate via graded local electrotonic hyperpolarizations or depolarizations?

Back 24

Ganglion Cells

Front 25

What happens to the on-center receptor during an off-surround response?

Back 25

It is depolarized by the horizontal cell (lateral inhibition)

Front 26

What happens to the on-center ganglion cell during an off-surround response (depolarized, hyperpolarized)?

Back 26

Hyperpolarized (cell firing rate is decreased)

Front 27

What is the function of the on center/off-surround retinal organization?

Back 27

It functions to sharpen boundaries between areas of light and dark

Front 28

If both on center and off-surround receptors are equally stimulated, then the ganglion cell firing rate (increases, decreases, both, neither)?

Back 28

Neither (basal rate is maintained)

Front 29

How many types of cones are there in the human retina?

Back 29

3 types

Front 30

By itself, can a cone tell the difference between a change in color or light intensity?

Back 30

No (it is colorblind by itself)

Front 31

Which cones are the least sensitive to light (blue, green, red)?

Back 31

Blue

Front 32

Which cones are the most sensitive to light (blue, green, red)?

Back 32

Red

Front 33

Which cones are found in the central part of the fovea and play a role in resolving fine detail?

Back 33

red and green

Front 34

What problem is eliminated by not having blue cones in the central fovea?

Back 34

chromatic abberation (blurred images due to a greater refraction of blue light by the lens)

Front 35

Are more men or women red-green color blind?

Back 35

More men (X-linked recessive)