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Physiology > Unit 2: Sensory Physiology > Flashcards

Unit 2: Sensory Physiology Flashcards

1
Q

A _____________ is how a receptor responds to a stimulus

A

sensation

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2
Q

__________ is the thing that initiates activity at a sensory receptor [ex) sound]

A

stimulus

[something you are exposed to]

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3
Q

_________ is what you feel

A

Perception

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4
Q

What 3 things must receptors be able to do?

A
  1. distinguish different stimuli from each other (stimulus modality) AKA: specificity = adequate stimulus
  2. determine the location of the stimulus (anatomy)
  3. determine stimulus amplitude (property of neuron)
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5
Q

Define sensation

A

sensing the existence of a stimulus

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6
Q

define perception

A

interpretation of information from the environment so that we can identify its meaning

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7
Q

Describe the structure of a sensory receptor with reference to the neuron

A

3 types

  1. most basic- just dendrites [free nerve ending]
  2. wrapped dendrites
  3. specialized receptor cell
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8
Q

Some receptors have non-neural accessory structures, what is the general purpose of these accessory structures?

A

they wrap the dendrite so the stimulus is applied to them first, then it relays info to the dendrite

general purpose: act as an intermediate between stimulus applied and the dendrite; in this process, they can modify the stimulus ~could amplify, focus, or oppose/block stimulus

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9
Q

List the five different functional types of receptors

A

chemoreceptor- chemical
thermoreceptor- temp
mechanoreceptor- mechanical
photoreceptor- vision
nociceptor- pain

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10
Q

define “adequate stimulus”.

A

what a specific receptor is sensitive to

specific type of stimulus it can respond to

ex) touch receptor : touch stimulus

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11
Q

How are different specific stimuli distinguished at the receptor level and at the CNS level?

A

Receptor: only the corresponding receptor respond > sends signal to brain > interprets that this stimulus is this type based on AP frequency

CNS: which part of the brain becomes stimulated due to receptor being stimulated

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12
Q

Explain how lateral inhibition contributes to stimulus localization.

A

inhibition of lateral neurons enhances the perception of the stimulus

lateral inhibition definition - a divergent neural circuit that results in lateral divergent branches inhibiting their target cells; central neuron has inhibitory affect on lateral neurons

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13
Q

How is the intensity of a stimulus represented in a single neuron?

A

Proportional to amplitude of graded potential

frequency of action potential

NT quantity in synaptic cleft

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14
Q

Describe the characteristics of a “phasic’ receptor.
Provide an example.

A

fast adapting receptor

most common.

~receptor responds to change in stimulus

the response will be quick initially and will slow down although the stimulus is unchanged when continuously stimulated

ex) temperature, smell, vision

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15
Q

Describe the characteristics of a “tonic’ receptor.
Provide an example.

A

~receptor exhibits tone when off, but also exhibits a fixed amount of activity/ tone when it is on

slow adapting receptor

ex) pain receptor

less common.

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16
Q

Describe how the structure of the Pacinian corpuscle contributes to its phasic nature.

A

when a stimulus is applied, the CT layers dimple inward, stimulating the receptor; as the stimulus is continuously applied, the CT layers will go back to their original state, so the stimulus is not being relayed to the dendrite

Due to its accessory structures, it is very phasic.

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17
Q

What type of cells function as olfactory receptors?

A

~Bipolar neurons~

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18
Q

Describe the structure of the taste receptor (taste bud). What type of cells function as receptors?

A

encapsulated dendrites synapsing on transducer/gustatory cells

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19
Q

How is the tone of a sound (soundwave frequency) differentiated at the cochlear level? At the CNS level?

A

each tone/identity of sound stimulates a different group of hair cells > vibration in different parts of basilar membrane.

cochlear - different tones stimulate different hair cells

CNS- different parts of cortex stimulated

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20
Q

How is the volume of a sound (soundwave amplitude) differentiated at the cochlear level?

A

volume of a sound = how big is stimulus

bigger stimuli = larger graded potentials = AP in higher frequencies > increasing NT released

Volume = how much hair cells bend

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21
Q

Describe how the central retina (i.e. fovea centralis) and the peripheral retina differ both structurally and functionally.

A

central- more cones, so better color discrimination
~greater visual acuity due to less convergent neural circuit

peripheral- more rods than cones; almost completely colorblind here
~more convergence here = lower amplitude stimulus needed for nerve impulse

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22
Q

Why is the central retina better able to distinguish color and details while the peripheral retina is better able to distinguish weak visual stimuli?

A

The high packing density of cones and the low convergence of cones onto bipolar cells in the macula support higher visual acuity in the central visual field.

each photoreceptor/cone responds to unique and discrete point of light = unique signal to brain

in peripheral retina, there are giant receptive fields; don’t know where the stimulus is applied exactly; acuity much lower here. but sensitivity is gained like to dim lights

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23
Q

Describe the neural pathway from the light receptor cells in the eye to the visual cortex in the brain.

A

Light is the stimulus

Cornea > Pupil > lens > retina > ganglion cells (do not respond) > bipolar neurons (do not respond) > photoreceptors (respond and initiate nerve impulse)

> NT release > bipolar cells > ganglion cells > AP down axon > optic nerve > optic chiasm > optic tracts > thalamus > occipital lobe (visual cortex)

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24
Q

Explain how changes in the shape of the lens change the focal point of vision.

A

changes in the shape of the lens are achieved through the contraction and relaxation of the ciliary muscles.

When you look at distant objects, the lens is relatively flat, focusing distant light rays onto the retina.

For near vision, the lens becomes thicker and more rounded, allowing it to bend light more sharply and focus near objects onto the retina.

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25
Q

Explain how color vision works. Example: how can we see yellow if we do not have photoreceptors specifically sensitive to yellow

A

yellow may be associated with wavelength in between the 3 cones

yellow light stimulates all 3 cones unequally, so the signal to the brain is a code, telling the brain it must be yellow light, bc only yellow light would create this pattern of stimulation of the 3 cones.

when brain receives this pattern > must have been yellow to receive this code > so we see color yellow

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26
Q

The ear can be divided into 3 main regions:

A

outer ear
middle ear
inner ear

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27
Q

The outer ear includes

A

auricle
external auditory canal
tympanic membrane

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28
Q

The outer ear conducts sound (pressure waves) to the

A

tympanic membrane (eardrum)

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29
Q

The oscillating pressure waves that carry sound will cause the thin drum-like structure of the tympanic membrane to:

A

vibrate as it is struck by alternating high and low pressures

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30
Q

The middle ear is an air-filled chamber that has 3 interconnected bones (ossicles)

A

malleus
incus
stapes

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31
Q

The ____________ is responsible for the transmission of sensory info to the brain to be processed and integrated

A

optic nerve

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32
Q

The sensory receptor responds to a:

A

stimulus

ex) light/color, sound, warmth

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33
Q

The most basic sensory receptor is

A

free nerve ending

just dendrite

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34
Q

sensory receptors that can respond to a chemical are called:

examples?

A

chemoreceptors

[including taste, smell, awareness of hunger/blood conc.]

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35
Q

Sensory receptors that can respond to mechanical stimuli are:

examples?

A

mechanoreceptors

ex) touch, need to pee (bladder stretch), balance, hearing

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36
Q

Thermoreceptors respond to:

A

temperature

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37
Q

Photoreceptors require a ________ cell

A

Transducer

to convert light to chemical stimulus that dendrite can respond to

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38
Q

Photoreceptors are associated with sense of:

A

vision

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39
Q

_____________ are receptors associated with pain

A

Nociceptor

[similar to chemoreceptor but has unique role]

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40
Q

the brain exhibits ___________, meaning it can re-arrange the processing centers within the brain to maximize amount of available “mental real estate” for a specific task

A

plasticity

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41
Q

________ receptors exhibit adaptability

A

Sensory

important characteristic!

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42
Q

Describe the pacinian corpuscle structure

A

dendrite wrapped by many layers of CT (accessory structures)

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43
Q

Describe the distribution and responsiveness of the following receptor:

root hair plexus

A

dendritic ending that wraps around hair follicles

any time the hair follicle bends due to wind, dendrites will bend, stimulating them

provides us awareness of anything that moves hair on our skin

ex) awareness of light breeze

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44
Q

Describe the distribution and responsiveness of the following receptor:

Golgi tendon organ

A

tension sensitive- detects how much strain is applied to the tendon by contraction of a muscle or limb movement

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45
Q

Describe the distribution and responsiveness of the following receptor:

muscle spindle.

A

sensitive to length changes in muscle

once muscle length changes, it resets for the next change

distributed throughout skeletal muscles, particularly in those involved in fine motor control. It serves as a highly responsive receptor that detects changes in muscle length and the rate of change, playing a crucial role in proprioception and motor control.

The information provided by muscle spindles is used to regulate muscle tone and ensure precise movements and postural stability.

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46
Q

___________ ___________ are very sensitive even to weak stimuli [light touch sensitive receptor]

A

Meissner’s corpuscles

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47
Q

______ _______ __________ are abundant within the skin; may be associated with pain/temperature sensitivity.

A

Free nerve endings

48
Q

___________ receptors may be free nerve endings

A

temperature/ pain

49
Q

The one sensory receptor type that is everywhere EXCEPT structure of the CNS are:

A

proprioceptor

[muscle spindles, golgi tendon organ]

50
Q

what is the sensory receptor type that responds to a stimulus you will never feel?

A

muscle spindles

51
Q

proprioception is

A

sense of limb position and movement

52
Q

The olfactory pathway is unique how?

A

neurons do not go directly to the thalamus, they go to the cortex

53
Q

The specific region of the ______ ____________ that is activated is a result of the location of the tactile stimulus and thus is how the location of a tactile stimulus is perceived.

A

somatosensory cortex

54
Q

Sensory receptors that respond strongly when a stimulus is first applied but do not continue to respond even if the stimulus is still present are called:

A

phasic receptors

55
Q

A change in membrane potential within a sensory receptor when stimulated is a graded potential , and it is called a(n) :

A

receptor potential .

56
Q

The number of odors that we can distinguish is significantly _________ than the number of unique olfactory receptors that we have.

A

greater

57
Q

ALL sensory receptors are composed of _________ at the core of their structure.

A

dendrites

58
Q

Each specific receptor is most sensitive to a specific type of stimulus referred to as the receptor’s:

A

“adequate stimulus”.

59
Q

Most sensory receptors are described as “phasic”. What does this mean?

A

sensory receptors “adapt” to continuous stimuli

60
Q

Which of the following do sensory receptors do poorly:

Determine the location of a stimulus
Determine stimulus amplitude
Determine how long a stimulus lasts
Distinguish different stimuli from each other

A

Determine how long a stimulus lasts

61
Q

the inner ear has 2 main regions:

A

cochlea
vestibular complex

62
Q

Cochlea is associated with

A

sense of hearing

63
Q

the vestibular complex is associated with

A

sense of balance

64
Q

The vestibular complex is composed of

A

the vestibule with utricle and sacule (awareness of gravity)

& semicircular canals (rotational awareness)

65
Q

the inner ear is more of a ___________ than a structure in the temporal bone

A

space

66
Q

the membranous labyrinth is filled with:

A

endolymph

67
Q

the inner ear space is filled with a fluid called

A

perilymph

68
Q

Within the ____________________ of the ear are the sensory receptor structures

A

membraneous labyrinth

69
Q

Inside the membraneous labyrinth, there are transducer cells that are mechanoreceptors and are sensitive to:

A

anything that causes bending to microvilli like structures

70
Q

The bending of the microvilli like structures in the ear stimulates:

A

mechanically gated channels > awareness of bending

creates a membrane potential change/ graded potential

71
Q

What causes the microvilli in the ear to bend?

A

tectorial membrane

[basilar membrane vibrates, causes hair cells to be compressed against tecortial membrane > bending > stimulating nerve impulse bc hair cell releases NT on dendrites of sensory neuron]

72
Q

The hair cells inside the utricle and saccule are associated with the _________________ that sits on top of them and is filled with crystals that make the mass heavy so it falls downward

A

gelatinous mass

73
Q

the utricle and saccule are associated with __________ equillibrium

A

static

[orientation to gravity and linear acceleration]

awareness of gravity.

74
Q

in the semicircular canals are hair cells that project into a gelatinous mass called the

A

cupula

75
Q

The cupula acts like a ______; if the surrounding endolymph moves left to right, the sail also bends left to right, bending the hair cells

A

sail

76
Q

The semicircular canals & cupula are associated with ____________ equillibrium

A

dynamic

[orientation to angular acceleration]

77
Q

the cornea is shaped as a lens and contributes to the:

A

focusing of light on to sensory receptors at the back of eye

78
Q

Just behind the cornea is the iris, which is the muscle that forms the opening at the center. The Iris’ job is to regulate:

A

diameter of pupil

how much light enters eye

79
Q

The lens does what?

A

bends and focuses light

80
Q

Ciliary muscles can contract and relax to adjust lens shape in order to bring light that is further or closer to us in to focus. This is called:

A

the accomodation reflex

81
Q

The light that shines into the eye is going to form an image on the:

A

retina

[receptors will respond to the light]

82
Q

myopia and hyperopia is what

A

change in eye shape

near vs far sighter

83
Q

Astigmatism is an irregularity in the curvature of the

A

cornea

[rays do not focus; part of image is blurry]

84
Q

What are the 3 layers of the retina?

A

1) ganglion cells

2) bipolar cells

3) photoreceptors

85
Q

What are the 3 types of cones?

A

Red cones
Green cones
Blue cones

RGB

86
Q

There is ____ type(s) of rod cells

A

1

87
Q

_____ cells cannot diffentiate different colors

A

rod

however they do not have equal sensitivity to all colors either.

88
Q

Rods respond to most of the color spectrum, except

A

part of the spectrum that only red cones respond to

89
Q

the eye feeds sensory info out the optic nerve > optic chaism > axons continue onward and don’t terminate until they get

A

to the thalamus

90
Q

The right side of the brain receives sensory signals from receptors on the

A

left side of the body

and vice versa

91
Q

Contralateral relationship is

A

right brain associated with left side of body

left brain associated with right side of body

92
Q

The right visual field is assciated with

A

left side of brain

93
Q

each side of the brain receives ____________________________ of visual info

A

2 different versions

[from right, and left eye]
> 2 images being processed in each half of brain.

94
Q

where is the blind spot?

A

in the retina where the optic nerve connects.

no photoreceptors = no ability to detect light stimuli

95
Q

Where there is less cones and more rods, the ability to discriminate color:

A

decreases

96
Q

central vision is much more able to discriminate colors compared to peripheral visions due to:

A

presence of more cones

97
Q

with _____ there is convergence

A

rods

rods>convergence>bipolar cells>ganglion cell&raquo_space;> no discriminatrion, only 1 signal produced

[no converence with cones]

98
Q

How does the CNS use summation to evaluate stimulus intensity?

A

CNS level -

frequency of AP arriving

and looks at how many neurons carry the same info

spatial summation.

99
Q

Define “modality”

A

Textbook definition: the nature of a stimulus

the different specific stimulu

ex) vision- colors of light
Ex) hearing - tones of sound

100
Q

Define “nystagmus”.

A

An involuntary eye movement which may cause the eye to rapidly move from side to side, up and down, or in a circle, and may slightly blur vision.

101
Q

Which structures monitor the rotational acceleration of the head?

A

semicircular canals

102
Q

The peripheral retina (responsible for peripheral vision):

is made primarily of ___1_____

has greater _____2______ sensitivity than the central retina

has _____3_____ acuity than the central retina

& is color blind.

A

1- rods

2- low light

3- lower

103
Q

The ciliary muscle helps to control:

A

the shape of the lens

104
Q

The right side of the brain receives visual inputs from:

A

both eyes, but only images from the LEFT side part of the visual world that each eye can see

105
Q

In regions of the retina where there is greater convergence of photoreceptors onto ganglion cells, visual acuity would _____1_____ and sensitivity to low light would _____2____

A

1- decrease
2- increase

106
Q

The tone of a sound is distinguished from all other tones by:

A

which hair cell is bent

107
Q

All of the receptors in the inner ear are composed of the same transducer cell type, called :

A

a hair cell.

108
Q

The volume of a sound is another way of describing:

A

the amplitude of the actual sound wave

109
Q

Different volumes are distinguished by :

A

how much a hair cell is bent

110
Q

The frequency of action potentials in the auditory nerve is an indicator :

A

of volume

111
Q

Which neurons in the auditory nerve relay the signal is an indicator:

A

of tone

112
Q

tone of sound is another way of describing the:

A

frequency of the actual sound wave

113
Q

How is eye movement & stabilization influenced by the vestibular apparatus?

A

semicircular canals detect head movement and allow eyes to stay fixed while eye is turning

Detecting Head Movement:
Semicircular canals; When the head moves, the fluid moves & stimulates the hair cells in the canals, which send signals to the brain to detect the direction and speed of head movement.

Maintaining Gaze Stability:
counteract the involuntary movements of the head, such as when walking or turning.
[vestibulo-ocular reflex]

Balancing the Body:
The vestibular apparatus contributes to balance and spatial orientation.

114
Q

What is necessary for two identical and simultaneous stimuli to be distinguished from each other?

A

they must stimulate different receptors & be connected by different neurons > different signals in the brain

115
Q

pressure, stretch, and thunder would be an adequate stimulus for :

A

a mechanoreceptor

116
Q

light from the environment first enters eye through the

A

cornea

Physiology (20 decks)

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