PSL300 Term Test 3

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what are the 5 special senses?

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154 Terms

1

what are the 5 special senses?

vision, hearing, equillibrium, taste and smell

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2

what are the 4 somatic senses?

touch, temperature, proprioception and nociception

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3

receptors are

cells which convert stimuli into electrical signals (transduction)

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4

what is a neuron?

vision sensory cell

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5

every sensory system begins with

receptors

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6

receptor potential

a receptor cell converts stimulus energy into a graded change in membrane potential

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7

every type of receptor cell has an

adequate stimulus

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8

adequate stimulus

the form of energy to which a receptor is most responsive (ex thermoreceptors are sensitive to temp)

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9

receptors are classified according to their

adequate stimulus

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10

chemoreceptors

respond to specific molecules/ions

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11

mechanoreceptors

respond to mechanical energy such as pressure, vibration, gravity, sound

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12

thermoreceptors

respond to temperature

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13

photoreceptors

responds to light

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14

receptor threshold

the weakest stimulus that will cause a response in a receptor

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15

perceptual threshold

the weakest stimulus that will cause a conscious perception in the organism

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16

sensory systems involve a series of

neurons

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17

primary sensory neurons synapse onto

secondary sensory neurons

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18

convergence allows

secondary and higher neurons to combine data from multiple receptors

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19

sensory neurons carry info about many aspects of the stimulus, one aspect is

modality (what is the mode/source: light, sound, touch)

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20

groups of neurons can represent intensity in __ ways which are

  1. population coding of intensity: # of active neurons

  2. frequency coding: stronger stimuli may make individual neurons to fire at a faster rate

both mechanisms can work together

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21

receptors are neurons have

dynamics (changes in stimuli, not in steady levels)

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22

different cells have different dynamics, the 3 types of cells are:

  1. phasic cells

  2. tonic cells

  3. phasic-tonic cells

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23

phasic cells are

cells which respond to a stimulus for a brief moment/change and then stop (FADE AWAY)

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24

tonic cells

are cells that maintain their activity when the stimulus is not changing (at present level)

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25

phasic-tonic cells

are cells that react to change but don't stop/ go to 0 firing when the stimulus is constant. They also carry info about the steady level

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26

many retinal cells are

phasic

example: waving your arm to get a friend's attention will activate the phasic cells in their retina

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27

______ cells make communication more efficient

phasic

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28

since our world is fairly stable, it is more efficient to report changes that occur when there is change between time, this change is called __________

temporal change (change through time) ex. the weather stations

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29

it is also efficient to report ________ changes, which are:

spatial changes - differences between neighbouring regions in space ex. darker triangle vs lighter triangle in a square

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30

spatial changes are also known as _________

contrast

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31

locations where there is a strong contrast between two spaces are called _______

edges

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32

sensory systems accentuate edges (make them noticeable) by:

lateral inhibition: cells can inhibit their neighbours or they can inhibit the cells their neighbours excite ex (an object poking the skin would have an edge between contact and no contact)

<p>lateral inhibition: cells can inhibit their neighbours or they can inhibit the cells their neighbours excite ex (an object poking the skin would have an edge between contact and no contact)</p>
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33

away from the edge, __________ and _________ cancel out

excitation and inhibition

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34

most sensory pathways run via the ________ to the _______

thalamus -> cortex

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35

one pathway that does not send signals from the thalamus to the cortex is the:

olfactory (smell) pathway - goes straight from nose -> cortex

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36

equillbrium (balance) pathways project mainly to the _________

cerebellum

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37

sensory processing is ___________

inference (educational guessing) - unconscious and fast

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38

since the brain has to guess, it can be fooled. the brain also ______ coincidences

mistrusts

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39

the eye is divided into __ chambers by the ___ . These chambers are the:

  • 2, lens

  • anterior chamber, vitreous chamber

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40

the anterior chamber:

is filled with aqueous humor (plasma like fluid)

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41

the vitreous chamber is:

filled with clear jelly that maintains they eyeballs shape

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42

the ______ is a transparent buldge, the outer wall of the eye

cornea

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43

the ____ is a transparent disk that focuses light

lens

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44

the _____ and ____ focus light on the _____, the inner lining of the eye which contains photoreceptors

  • cornea

  • lens

  • retina

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45

light passes from the ____ to the lens through a hole in the ___ called the ____

  • cornea

  • iris

  • pupil

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46

the pupil can change ___

size

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47

in bright light, the pupil _____ to ____ the amount of light reaching the ____

  • constricts/shrinks

  • reduce

  • lens

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48

in the dark, the pupils ____ to _____ the amount of light that reaches the ___

  • dilates/expands

  • increase

  • lens

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49

the pupil is controlled by _____ muscles in the ____

  • smooth

  • iris

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50

in bright light, _________ signals from the brain contract the ____ _______ muscle, shrinking the pupil

  • parasympathetic (long=light)

  • pupillary constrictor

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51

in the dark, ___________ signals contract the _____ ______ muscle, _____ the pupil

  • sympathetic

  • radial pupillary

  • dilating

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52

the _____ helps to focus light and control _________________

  • pupil

  • depth of field (what you can see around you and how much of it)

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53

when the pupil is dilated, we have a ____ depth of field. this means only objects ___ one specific distance are in ____

  • shallow

  • near

  • focus

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54

when the pupil is tightly constricted, we have ____ depth of field, which means everything we see is ____ in _____

  • full

  • equally

  • focus

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55

the problem with using the pupil alone to focus light is that:

  • the retinal image is dull

  • enlarging the pupil makes the image brighter and blurrier (B&B)

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56

in order to get a retinal image that is both ____ and _____, we rely on ________

  • bright

  • focus

  • refraction

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57

the bending of light is known as:

refraction

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58

light ____ when it enters a medium with a ______ refractive index

  • bends

  • different

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59

our corneas are made of _______. they bend strongly because there is a big difference between the ____ _____ of air and collagen

  • collagen

  • refractive index

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60

the cornea is responsible for _____ of the eye's refraction. while the lens accounts for ____

  • cornea = 2/3

  • lens = 1/3

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61

the lens of the eye is ____. These lenses are flatter in the middle and thinner at the edges. (ex: magnifying glass)

  • convex

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62

refraction depends on the:

angle of incidence

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63

a ____ lens bends light more, and so it has a closer _____ _____

  • rounder

  • focal point

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64

for clear vision, the ____ ____ must fall on the ___

  • focal point

  • retina

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65

if the objects draws closer, but the lens stays flat, focus falls ___ the ____

  • behind

  • retina

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66

to bring a closer object into focus, we make the lens ______. This process is called ______ and is an _____ reflex

  • rounder

  • accomodation, unconscious

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67

what is hyperopia? where does the focal point fall and how can it be solved?

  • far-sightedness

  • behind the retina

  • solved by convex lens (reading glasses)

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68

what is myopia? where does the focal point fall and how can it be solved?

  • near-sightedness (MY EYESIGHT)

  • in front of the retina (NEAR AND FRONT)

  • can be solved with concave lens

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69

a ______ lens causes light rays to ____ ____ more, which is the opposite of a ____ lens

  • concave

  • spread out

  • convex

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70

photoreceptors are found in the

retina

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71

our retina has ___ types of photoreceptors which are:

  • rods

  • cones

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72

rods and cones are ______, however they do not fire ________ potentials. instead, the respond to ______ with _____ membrane potentials

  • neurons, action potentials, stimuli, graded

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73

cones and rods have the ______ basic structure. in the ___ segment, the membrane folds into ___________ layers which contain __________ that respond to light

  • same

  • outer

  • disk-like

  • visual pigments

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74

how do photoreceptors detect light?

  • they detect light using membrane bound visual pigments

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75

photoreceptors are _______ and more ______ in darkness. this means they release lots of ________

  • depolarized

  • active

  • glutamate

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76

each photoreceptor contains ____ of molecules of its _______. However, each type of photoreceptor has just ____ type of _____.

  • millions

  • pigments

  • one

  • pigment

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77

the visual pigment for rods is:

rhodopsin

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78

photoreceptors are not distributed ________. They are most densely packed in the _____, and especially in its central pit called the ______.

  • uniformly/equally

  • macula

  • fovea

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79

we use the ______ for detailed vision

fovea

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80

there are _____ photoreceptors in the ____ spot. The ____ spot is the hole where axons carrying ____ info exit the eyeball to form the ____ nerve.

  • no

  • blind

  • blind

  • optic

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81

cones are for _______ and rods are for ________.

  • bright light

  • dim light

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82

Therefore, _____ are considered to be more sensitive than _____ because they can detect single photons but they only operate in _____ light.

  • rods

  • cones

  • dim

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83

During daylight, ____ are bleached out, which means their _____ is broken down so they can't sense light

  • rods

  • rhodopsin

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84

cones and rods are distributed differently in the _______. The _____ contains exclusively ______ and the more peripheral ______ contains mainly _____. Therefore, there is a ____ density of _____ in the fovea.

  • retina

  • fovea

  • retina

  • rods

  • high

  • cones

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85

photoreceptors synapse onto ______ cells, which synapse onto _______ cells. up to ______ photoreceptors may converge on a single _______ cell, the BP cells in turn converge on ___.

  • bipolar

  • ganglion

  • 45

  • GC

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86

convergence is greatest in the peripheral _____ and least in the ______

  • retina

  • fovea

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87

everyone neuron in the visual system has a _______________ also called the _____ field. the ______ is the region of the ____ where light affects the cell's activity.

  • receptive field/visual field

  • visual field

  • retina

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88

bipolar cells receptive fields can be on centre or off centre. ___________ are excited by light in the centre of their field and ____________ by light in the surround. These cells respond most when a light spot fills their _____ and the surround is _____.

  • on centre cells

  • inhibited

  • centre

  • dark

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89

off centre cells are ___________ by light in the centre, and excited by ______ in the surround. they respond best when a _____ spot fills their centre and the surround is _________.

  • inhibited

  • light

  • dark

  • light

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90

both types of bipolar cells react to ___________. when lighting is _________, neither type of _____________ responds. this is because the effects of the centre and surround ___________, which leaves the cell at its ___________ level.

  • contrast

  • uniform

  • bipolar cells

  • cancel

  • resting

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91

bipolar cells project to ___________ ___________ ______.

  • retinal ganglion cells

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92

retinal ganglion cells unlike photoreceptors and bipolar cells, do:

  • fire action potentials

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93

ganglion cells in ___________ parts of the retina have different sized ___________. Therefore, a ganglion cell near the ______ gets input from only a few ___________, which are mostly ____.

  • different

  • receptive fields

  • fovea

  • photoreceptors, cones

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94

farther out, each ganglion cell gets input from many ________, which are mostly ______.

  • receptors

  • rods

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95

in the periphery, each ganglion cell is very ___________ to light, but ____ at reporting spatial detail. this is because it blends information from a wide range of ________.

  • sensitive

  • poor

  • receptors

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96

___________ are also classified based on how their signals are used in the brain.

ganglion cells

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97

large ganglion cells are ___________. these cells provide info about ___________ and are ________. they account for about _____ of RGC.

  • magnocellular ganglion cells/ M cells

  • M = MOVEMENT

  • phasic

  • ~10%

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98

small ganglion cells are ___________. these cells provide info that is used to infer form and fine detail, like texture. they are less ______ and more ___________. they account for about ___ of RGC.

  • parvocellular / P cells

  • phasic-tonic

  • ~70%

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99

~1 % of ganglion cells are ___________ ganglion cells. there are photoreceptors with their own ________ ___________.

  • melanopsin

  • visual pigment (melanopsin)

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100

half the optic-nerve fibres cross at the _______ ___________.

optic chiasm.

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