Duplex Retina

Question 1

A source with which of the following color temperature will appear most red

Answer 1

2000k

Question 2

The color temperature of an incandescent bulb is 3300K. This means

Answer 2

The bulbs spectral distribution matches that of a blackbody radiator whose temperature is 3300K

Question 3

A neutral density filter transmits 50% of 450nm light that is incident upon it. If 40W of 550nm are incident on the filter, how many watts are transmitted

Answer 3

20

40x50%=20W
Wavelengths doesn’t matter, it transmits all wavelengths equally

Question 4

The least amount of distortion is present with sunglasses made with a

Answer 4

Neutral density filter

Question 5

Which of the following light sources has more energy concetrated in the blue region of the spectrum

Answer 5

LEDs

Question 6

What is the adaptional range of the human eye

Answer 6

10^-6 to 10^10

Question 7

What makes it possible for the human eye to see something very bright and something very feeble in the night sky?

Answer 7

The pupil, but the pupil is good for only 1 log unit, the rest is from the retinal photoreceptors

Question 8

How does pupil help make humans able to see bright and dark

Answer 8

By changing its diameter in response to light, helps to control the amount of light that falls upon the retina

Question 9

How many log units does the pupil contribute to sensitivity of light

Answer 9

1 log unit

Question 10

How can the eye adjust to a 10-log unit range of retinal luminance if the pupil can only account for 1 log

Answer 10

Retinal photoreceptors, rods and cones

Question 11

Things about scotopic vision

Answer 11

• sensitive to dim lights
• poor VA
• absence of color discrimination
• mediated by rods

Question 12

Photopic vision things

Answer 12

• poor sensitivity to dim lights
• excellent VA
• color discrimination
• cones mediate photopic vision

Question 13

The existence of two classes of photoreceptors, each operating under different lighting conditions, referred to as a

Answer 13

Duplex retina

Question 14

Under _____________conditions, both rods and cones contribute to vision

Answer 14

Mesopic conditions

Question 15

Contained within the discs of the rods outer segment

Answer 15

Rhodopsin

Question 16

One eye contains about ______ rods

Answer 16

120 mill

Question 17

Each rod contains ______ disks

Answer 17

1000

Question 18

Each disk within a rod contains ________rhodopsin molecules

Answer 18

10,000

Question 19

How many rhodopsin molecules per eye

Answer 19

10^15

Question 20

Each molecule of one rhodopsin is capable of absorbing ______ photon of light

Answer 20

One

Question 21

The absorption of _____photon (s) is sufficient to activate a rod

Answer 21

One

Question 22

The large number of rhodopsin molecules capture light and contributes to our exquisite _______ under nighttime lighting conditions

Answer 22

Sensitivity

Question 23

The absoprtion of light quanta by the photosensitive pigment in the outer segment causes the photoreceptor to become ____________. This is the first step in a sequence of events that ultimately leads to vision.

Answer 23

Hyperpolarized

Question 24

Light quanta that are incident on the rhodopsin, but not transmitted, have been ________

Answer 24

Absorbed

Question 25

Relationship of the absoprtion curve and the transmission curve

Answer 25

Reciprocal

Question 26

Light quanta of _______nm have the highest probability of absorption in rods

Answer 26

507nm

Question 27

Wavelengths other than 507 in rods

Answer 27

Are absorbed, but with less probability

Question 28

Once a quanta of light is absorbed, all information regarding its wavelength is lost, a principle referred to as ______________

Answer 28

Univariance

Question 29

A molecule of rhodopsin becomes ______when it absorbs light

Answer 29

Bleached

Question 30

The absoprtion of __________ is required to bleach a molecule of rhodopsin

Answer 30

One quantum of light

Question 31

When a rhodopsin meolcule is in the bleached state, it is not capable of capturing another quantum, it will

Answer 31

Transmit a quantum of light incident on it

Question 32

A bleached molecule will _________ to the unbleached state

Answer 32

Spontaneously revert back

Question 33

50% of the rhodopsin will recover in 5 minutes. This is referred to as

Answer 33

The half life of rhodopsin

Question 34

What is the half-life for rhodopsin

Answer 34

5 minutes

Question 35

If you irradiate the retina with 1000 quanta of light at 507nm, you might successfully bleach _______ rhodopsin molecules

Answer 35

200 or 20%

Question 36

If you irradiate the same part of the retina with 1000 quanta of light at 580nm, you might bleach _____ rhodopsin molecules, since the longer wavelength is absorbed less effectively

Answer 36

100

Question 37

If you double the irradiance of 580nm light to 2000 quanta of light, you would bleach appx _______the number of rhodopsin molecules. This is equal to the result of bleaching the retina with 1000 quanta of 507nm light

Answer 37

Double the number (200)

Question 38

Physiological response of the visual system to 1000 quanta of 507nm light and 2000 quanta of 680nm light

Answer 38

It is the same

Question 39

Since the scotopic (rod) system produces one physiological response irrespective of wavelength, and it is possible to match the output signal for all wavelengths, by adjusting the brightness of the light. Therefore the scotopic system is _________; it has not wavelength discrimination

Answer 39

Colorblind

Question 40

Our ability to detect stimuli under scotopic conditions is circumscribed by the _________

Answer 40

Rhodopsin absorption curve

Question 41

Rhodopsin adsorption curve

Answer 41

- Dark adapt someone for 45 minutes, maximizing the regeneration of the rhodopsin - the minimum amount of energy required for the person to detect stimuli of various wavelengths is determined.

Question 42

The minimum amount of energy required for detection of a stimulus is referred to as the _______ for that stimulus

Answer 42

Threshold

Question 43

The sensitivity curve is the ________ of the threshold function. A low threshold indicates a high sensitivity

Answer 43

Reciprocal

Question 44

What is human scotopic spectral sensitivity function determined by

Answer 44

The absorption characteristics of rhodopsin

Question 45

_______ is sufficient to activate one rod

Answer 45

One quanta absorption

Question 46

How many rods activate a ganglion cell

Answer 46

10

Question 47

How many ganglion cells needed for there to be detection

Answer 47

10

Question 48

For these 10 quantal absoprtion to result in detection, they must

Answer 48

Occur within certain space and time constraints

Question 49

_______ of the quanta incident on the retina are absorbed by rhodopsin

Answer 49

Fewer than 20%

Question 50

Is a stimulus that emits 10 quanta visible?

Answer 50

No because many quanta are either reflected or absorbed by tissues inner to the photoreceptors (preretinal and retinal) or not absorbed by rhodopsin

Question 51

What are the 3 cone pigments

Answer 51

- cyanolabe/blue/426/S cone - chlorolabe/green/530/M cone - erythrolabe/red/557/L cone

Question 52

How many photopigments do each cone contain

Answer 52

One

Question 53

Where is the photopic spectral sensitivity

Answer 53

555

Question 54

Photopic spectral sensitivity shows a single broad peak in the region of

Answer 54

555nm

Question 55

What does the photopic spectral sensitivity curve represent

Answer 55

The addition of M and L cone absorption spectra

Question 56

S cones and the photopic spectral sensitivity

Answer 56

It is though that S cones make little, if any contribution to spectral sensitivity

Question 57

Where does the blue peek

Answer 57

Shorter than the rod (black line)

Question 58

The difference in sensitivity between scotopic and photopic systems, for a given wavelength is referred to as the

Answer 58

Photochromatic interval

Question 59

When is the photochromatic interval largest

Answer 59

At shorter wavelengths

Question 60

Where is the photochromatic interval medium

Answer 60

At medium wavelengths

Question 61

Where is the photochromatic interval switched, with the photopic being higher than the scotopic?

Answer 61

Longer wavelengths

Question 62

When does the photochromatic interval equal 0?

Answer 62

650nm

Question 63

When isthe photochromatic interval approximately zero and rods and cones are almost equally sensitive

Answer 63

Longer wavelengths

Question 64

Photochromatic interval beyond 650nm

Answer 64

The photopic system is slightly more sensitive than the scotopic system

Question 65

Photochromatic intervals ________with retinal eccentricity

Answer 65

Increase

Question 66

Photochromatic intervals int he fovea

Answer 66

Greatest for short, then medium, then long wavelengths

Question 67

Photochromatic wavelengths in the periphery

Answer 67

The order for short and medium wavelengths is reversed. The interval size for short and medium wavelengths increases at a negative rate and for long wavelengths at a positive rate

Question 68

Photochromatic intervals vary with

Answer 68

Stimulus size

Question 69

As lighting conditions change from scoptopic to photopic, the wavelength to which we are most sensitive increases from ______ to _____

Answer 69

507 to 555nm

Question 70

The relative increase in the brightness of longer wavelength stimuli as lighting conditions change from scoptopic to photopic

Answer 70

Purkinje shift

Question 71

How many rods in one eye

Answer 71

120 mill

Question 72

How many cones in one eye

Answer 72

6 mill

Question 73

What do the cones look like as you get further from the fovea

Answer 73

They get larger and mroe spaced out

Question 74

Ratio of L and M cones in people

Answer 74

Varies from person to person

Question 75

S cones distribution

Answer 75

Show a different retinal distribution than other cones. Not only are there considerably less numerous than either M or L ones, constituting appx 5-10% of the cone population, they are not found int he central 0.3-0.4 degrees of the human fovea

Question 76

What cones are not found in the fovea

Answer 76

S cones

Question 77

What cones are found in much less numbers in the retina

Answer 77

S cones

Question 78

Gradual improvement in vision, after exposure to bright-adapting light

Answer 78

Dark adaptation

Question 79

Rod and cone sensitivity recover

Answer 79

Recover at different rates, after exposure to bright lights

Question 80

What is recovery in sensitivity in rods and cones related to

Answer 80

The regeneration of photopigment molecules

Question 81

After 35 min in the dark, the eye is ______ more sensitive to light

Answer 81

100,000 times

Question 82

Cone plateau

Answer 82

10 minutes

Question 83

Rod-cone break

Answer 83

12 minutes

Question 84

From the point of cone plateau to the rod-cone break (10-12) minutes, what detects the stimulus

Answer 84

The cones

Question 85

Rod plateau

Answer 85

35 minutes

Question 86

Where does the rod cone break occur

Answer 86

At that point in time when the rods become more sensitive than the cones

Question 87

When do rods become more sensitive than cones

Answer 87

Rod-cone break, 90% of the rhodopsin as regenerated

Question 88

The different between the cone plateau, which represents the minimum photopic threshold for a stimulus, and the rod plateau, which represents the minimum scotopic threshold for this same stimulus

Answer 88

Photochromatic interval

Question 89

The photochromatic interaval is about ____ log units

Answer 89

3

Question 90

Bleaching to rod recovery is about ____ log units

Answer 90

5

Question 91

After _____ log units, sensitivity for rods increases

Answer 91

5

Question 92

What form does the dark adaptation curve take if the stimulus is 650nm?

Answer 92

It shows only oa cone portion, the rod aspect is missing, since the photochromatic interval for 650nm is 0. And because the scotopic system is not more sensitive than the photopic system, there is not an obvious rod-cone break

Question 93

The photochromatic interval for the 420nm stimulus

Answer 93

Large, consequently, this stimulus produces a dark adaptation curve with a prominent rod-cone break

Question 94

____ are not mroe sensitive than ____ for long wavelengths

Answer 94

Rods | Cones

Question 95

The stimulus used to generate the dark adaption curve

Answer 95

Is large and central fixeted. Such a stimumuls falls on both the fovea and surrounding retina

Question 96

What happens when you make the stimulus small when doing dark adaptation

Answer 96

Only a cone function is obtains, the absence of a rod function reflects the absence of rods in the fovea.