wk 2 SP

Question 1

when light changes in intensity, we perceive this as a change in…

Answer 1

brightness

Question 2

when light changes in wavelength, we perceive this as a change in…

Answer 2

colour

Question 3

what range of wavelength in nm can humans see

Answer 3

400-700nm

Question 4

Pupil between ~2 mm and ~___ mm diameter

Answer 4

9

Question 5

Cornea –__% focusing power
Lens –__% but can change shape due to action of _____muscles

Answer 5

80

20

ciliary

Question 6

Lens becomes fatter to focus _____objects

Answer 6

close

Question 7

Lens becomes thinner to focus ______objects

Answer 7

far

Question 8

Myopia

light focused ____ of retina

corrected with ____ lens

Answer 8

nearsightedness

in front

concave

Question 9

Hyperopia

light focused ____ of retina

corrected with ____ lens

Answer 9

farsightedness

behind

convex

Question 10

photoreceptors

how does transduction occour

Answer 10

light sensitive cells

carry out transduction

by visual photopigments reacting to light and trigger electrical signals

Question 11

2 types of photoreceptor

+ approx number

Answer 11

Rods (120 million)

Cones (6 mil)

Question 12

Rods vs cones in sensitivity

Answer 12

Rods

Very sensitive, respond well in very dim light

Most useful at night, useless in daylight

Cones

Less sensitive

Work best in daylight, useless at night

Question 13

scotopic

Answer 13

only rods active

Question 14

photopic

Answer 14

only cones active

Question 15

mesopic

Answer 15

both cones and rods active

Question 16

Bright light bleaches ________ so ______ stop responding

Going from bright to dark the _______ have to ‘recover’ or regain sensitivity.

Answer 16

photopigments

photoreceptors

photoreceptors

Question 17

Dark adaptation

Answer 17

increase in eye’s sensitivity in the dark

Question 18

After 20-30 minutes in the dark, sensitivity is about __________ times greater than the sensitivity in light

Answer 18

100,000

Question 19

rods or cones are Responsible for colour vision

Answer 19

cones

Question 20

3 types of cone, sensitive to different wavelengths of light:

Red (_____ wavelengths)

Green (_____ wavelengths)

Blue (______ wavelengths)

Answer 20

long

medium

short

Question 21

Rods

Produce ________ vision

(colour)

Answer 21

monochromatic

Question 22

how many types of rod cells are there, what are they most sensitive to

Answer 22

1 type - most sensitive to medium wavelengths (green light)

Question 23

Purkinje shift

Answer 23

• at night red looks darker than green

Question 24

On average…

___ rods send signals to 1 ganglion cell

__ cones send signals to 1 ganglion cell

Answer 24

120

6

Question 25

Rods have greater convergence – this leads to

Answer 25

lower acuity

can’t see fine details

Question 26

Cones have less convergence - this leads to

Answer 26

higher acuity

can see fine details