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Biology II > ch. 50 vision > Flashcards

ch. 50 vision Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what do most invertebrates have

A

light-detecting organ

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2
Q

simplest light-detecting organ

A

pair of ocelli called eyespots located near the head of planarians

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3
Q

what do eyespots of planarians do

A

allow planarians to move away from light and seek shaded locations (negative phototaxis)

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4
Q

what have ommatidia

A

insects, crustaceans, polychaete worms

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5
Q

compounds eyes

A

consist of several thousand light detectors called ommatidia

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6
Q

what are compound eyes effective at

A

detecting movement

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7
Q

color vision of insects

A

excellent - some can see ultraviolet range

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8
Q

where are single-lens eyes found

A

some jellies and polychaete worms, spiders, and many molluscs, vertebrates

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9
Q

how to single-lens eyes work

A

camera-like principle - iris changes diameter of the pupil to control how much light enters

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10
Q

choroid

A

thin, pigmented layer of the eye

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11
Q

what is just inside the choroid

A

retina with neurons and receptors

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12
Q

lens

A

transparent disk of protein

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13
Q

what is in front of the lens

A

clear and watery aqueous humor

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14
Q

what is behind the lens

A

jellylike vitreous humor

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15
Q

path of light through eyeball

A
  • cornea
  • aqueous humor
  • pupil - controlled by iris constricted/dilating
  • lens (living tissue)
  • vitreous humor
  • retina (photoreceptors, bipolar cells, ganglion cells)
  • optic nerve
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16
Q

what are the ciliary muscle connected to

A

the lens by suspensory ligaments - holds lens in place

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17
Q

myopia

A

focused in front of the retina

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18
Q

hyperopia

A

focused behind the retina

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19
Q

fovea

A

center of visual field compact with tons of cones and contains no rods

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20
Q

what is most of the retina composed of

A

rods

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21
Q

2 types of photoreceptors in retina

A
  1. rods
  2. cones
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22
Q

where do the neurons of the retina relay visual information to

A

the optic nerve and brain

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23
Q

optic disk

A

place in retina where optic nerve attaches to eye, lacks photoreceptors and forms a blind spot

24
Q

rods

A

more sensitive to light but don’t distinguish colors

25
Q

cones

A

provide color vision

26
Q

what do vertebrate visual pigments consist of

A

retinal bound to opsin

27
Q

retinal

A

light-absorbing pigment

28
Q

opsin

A

membrane protein

29
Q

ex. of vertebrate visual pigment

A

rhodopsin

30
Q

what does an absorption of light cause

A

change of shape in retinal

31
Q

glutamate in light

A

no glutamate released

32
Q

glutamate in dark

A

glutamate released as neurotransmitter from rods and cones to neurons called bipolar clues

33
Q

when light hits retinal, what happens to its shape

A

changes from cis isomer (bent) to trans isomer (straight)

34
Q

signal transduction in eyes

A
  • light changes cis-retinal to trans-retinal
  • trans-retinal activates rhodopsin
  • G protein activated - transducin activated
  • hydrolysis of cyclic GMP to GMP by phosphodiesterase
  • sodium channels close
  • cell hyperpolarized and rate of glutamate neurotransmitter release slows
35
Q

what does cGMP do in the dark

A

bind to sodium ion channels and keeps them open

36
Q

what happens when cGMP breaks down

A

Na+ channels close
- hyper polarizes cell

37
Q

how is the signal transduction pathway usually shut off

A

enzymes convert retinal back to cis form

38
Q

bleaching

A
  • light strikes cis-retinal and turns it to trans
  • bleaching occurs
  • ATP to ADP used by enzyme converts trans back to cis
39
Q

where does the processing of visual information begin

A

retina

40
Q

what does the decrease in glutamate do

A

change membrane potential of bipolar cells

41
Q

lateral inhibition

A

rod/cone stimulates horizontal cell, horizontal cell then habits more distant photoreceptors and bipolar cells
- regions receiving light appear lighter, dark surroundings appear darker

42
Q

what does a single ganglion receive information from

A

array of rods and cone
- defines receptive field

43
Q

what does a smaller receptive field typically result in

A

a sharper image

44
Q

optic chiasm

A

where optic nerves meet near center of base of cerebral cortex

45
Q

where are sensations from the left visual field of both eyes transmitted

A

to right side of brain and vise versa

46
Q

what vertebrates have good color vision

A

fish, amphibians, reptiles, birds

47
Q

what comprises the minority of mammals that can see color well

A

humans and primates

48
Q

mammals with nocturnal vision

A

have high proportion of rods in the retina and probably see a pastel world during the day

49
Q

what is the perception of color based off of in humans

A

3 types of cones

50
Q

3 types of cones

A

red, green, and blue - different visual pigments (photopsins)

51
Q

when are photopsins formed

A

when rental binds to 3 distinct opsin proteins

52
Q

what does abnormal color vision result from

A

mutations in the genes for one or more photopsin proteins

53
Q

what did researchers studying color vision in squirrel monkeys do

A

make breakthrough in gene therapy
- males are red-green color-blind
- when researchers introduced missing gene in virus, full color vision apparent

54
Q

focusing

A

changing shape of the lens

55
Q

near vision/accommodation

A
  • ciliary muscles contract
  • suspensory ligaments relax
    lens becomes thicker and rounder
56
Q

distance vision

A
  • ciliary muscles relax
  • suspensory ligaments pull against lens
  • lens becomes flatter

Biology II (43 decks)

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