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PT9111 - TEST 3 > Lecture 46 - Hearing, Olfaction and Gustation > Flashcards

Lecture 46 - Hearing, Olfaction and Gustation Flashcards

1
Q

Sound is measured in (2)

A

decibels or hurtz

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2
Q

Decibel

A

Smallest difference in loudness intensity that can be perceived

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3
Q

Frequency is measured in

A

Hertz

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4
Q

Frequency is equal to

A

Pitch

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5
Q

What are the 3 structures of the outer ear

A
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6
Q

What are the structures and muscles of the middle ear

A
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7
Q

Stapedius is connected to

A

The stapes and uses the facial nerve to dampen low tones

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8
Q

The tensor tympani is connected to

A

The malleus and uses the trigeminal nerve to dampen low tones

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9
Q

Bone conduction

A

Sound waves can be conducted through bones of skull

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10
Q

Hyperacusis

A

Hypersensitivity to sound because of damage to facial or trigeminal nerve

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11
Q

Eustachian Tube

A

Is a pressure equalizer and drain

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12
Q

2 structures of the internal ear

A
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13
Q

Cochlea

A

Sound waves are transduced into electrical signals that are then perceived by the brain

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14
Q

Membranous labyrinth is filled with

A

Endolymph

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15
Q

Bony labyrinth is filled with

A

Perilymph

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16
Q

What are the 3 fluid-filled spaces of the cochlea

A
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17
Q

What structure occupies the entire oval window to vibrate

A

Stapes

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18
Q

Pathway of sound in the cochlea

A

Scala tympani and Scala vestibuli contain the perilymph and are continuous with one another to the helicotrema
stapes vibrates -> oval window vibrates -> causes pressure waves in perilymph of scala vestibuli that go to helicotrema -> waves go to scala tympani -> round window -> also waves go to cochlear duct to transduce electrical signals that are sent to brain

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19
Q

Round window

A

Flexible membrane that releases pressure

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20
Q

T or F: If stapes and oval window move outwards, the round window moves inwards

A

T

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21
Q

What are the 2 key membranes of the cochlear duct and their function

A
  1. Reissner Membrane (Vestibular): Separates scala vestibuli and cochlear duct
  2. Basilar Membrane: Separates scala tympani and cochlear duct (contains hair cells = sensory receptors)
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22
Q

The cochlea has what type of localization

A

Tonotopic localization

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23
Q

Describe the frequencies found in tonotopic organization of cochlea

A

Apex = low frequency (wider and more flexible)
Base = High frequency (more narrow and less flexible)

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24
Q

The spiral organ of corti is made of

A

Receptor and supportive cells in the cochlear duct

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25
Q

The receptor hair cells of the organ of corti can be classified into what 2 groups

A

1) Inner hair cells
2) Outer hair cells

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26
Q

The hair cells are imbedded in the (auditory)

A

Tectorial membrane from the basilar membrane

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27
Q

How are signals activated through the basilar and tectorial membrane

A

When basilar membrane moves in response to sound or pressure waves in cochlea it creates a sheering force which activates hair cells by pushing them against the tectorial membrane that causes an activation signal

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28
Q

Compare inner hair cells and outer hair cells

A

Inner: Single row
Outer: 3-5 rows depending on location

Similarities: Both arrange stereocilia from shortest to longest and the stereocilia is embedded in the tectorial membrane

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29
Q

Bending towards stereocilia (longest hair cell)

A

causes depolarization

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30
Q

Bending away from stereocilia (longest hair cell)

A

causes hyperpolarization

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31
Q

What is the innervation of inner and outer hair cells

A

Hair cells are innervated by primary auditory neurons in spiral ganglion

Inner: 1:1 synaptic relationship with many ganglion cells (up to 20) which allows for greater tonotopic discrimination (discriminate between tones)

Outer: Each ganglion cell synapses on many hair cells and is innervated also by efferent olivocochlear fibers (superior olivary nucleus in pons) which increases height of outer hair cells and stiffness of stereocilia which influence basilar membrane to regulate selective attention to certain sounds (can alter response of inner hair cells and amplify sounds of particular regions of basilar membranes)

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32
Q

Do medications affect outer or inner hair cells

A

Outer hair cells

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33
Q

Frequency (tone) is coded by

A

the location of the basilar membrane activated

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34
Q

Intensity (measured in db) is coded by

A

Firing frequency of afferents and number of activated afferents (recruitment)

35
Q

Describe the auditory pathway starting with the hair cell

A
  1. Hair cells receive sound and innervated by ganglion cells
  2. Axons of ganglion cells form cochlear nerve
  3. Cochlear nerve projects to cochlear nuclei
  4. Cochlear nuclei span medulla and pons
  5. Cochlear nuclei decussates and projects ipsilaterally and contralaterally to each side (auditory pathway = bilateral)
  6. Superior olivary nucleus localizes sound because it receives input from cochlear nuclei on both sides of head
  7. Superior olivary nucleus in pons projects using olivocochlear fibers to the cochlea to regulate selective attention to certain sounds. They also play a role in acoustic reflex (attenuation) by dampening sound (trigeminal and facial nerve) and innervates muscle in middle ear. Superior olivary nucleus also projects to inferior colliculus (midbrain) via lateral lemniscus.
  8. Inferior colliculus communicates with contralateral inferior colliculus via commissure pathway. It also projects to thalamus (medial geniculate nucleus).
  9. Medial geniculate nucleus of thalamus projects auditory radiations to the primary auditory cortex
36
Q

Inferior Colliculus

A

All auditory pathways converge here and is responsible for signal integration and frequency recognition and discrimination

37
Q

T or F: In the auditory cortex we see tonotopy and neurons respond to increasingly complex stimuli differently

A

True

38
Q

T or F: Other cortical areas respond to auditory info

A

T (Wernicke’s Area)

39
Q

what happens with Lesions to auditory cortex
1. Whole cortex
2. Partial lesions

A

All cortex destroyed = deafness
Partial Lesions = can still show normal auditory perception due to redundancy of bilateral pathways

40
Q

T or F: tonotopy is observed in all parts of the auditory pathway

A

T

41
Q

How to determine hearing impairment

A

Use screening test of few key tones and compare to average threshold

42
Q

How to classify different types of hearing

A
43
Q

Deaf compared to profound/hard of hearing

A

Deaf is profound hearing loss and do NOT benefit from hearing amplification (eg. hearing aid)

44
Q

Conductive Hearing loss

A

1) Occurs in outer/middle ear
2) Affects intensity but not clarity
3) Responsive to surgical or medical intervention
4) Does not exceed 65dB
5) Benefit from hearing aid

45
Q

Sensorineural Hearing Loss

A

1) Occurs in inner hear
2) Affects conversion to neural impulses (hair cells damage)
3) Referred to nerve deafness and results in changes in perceived intensity and distortion of sound

46
Q

T or F: We are more sensitive to bad than good smells

A

T

47
Q

Pheromones

A

Chemical signals for reproductive behavior’s that trigger a social response

48
Q

Olfactory dysfunction results in

A

Negative interpersonal functioning

49
Q

What are the 3 different receptors/cells that make up the olfactory epithelium

A

1) Olfactory cells/receptors (blue) are neurons that penetrate the cribriform plate in the ethmoid bone and have cilia that project from surface (replaced every 4-8 weeks)
2) Supportive Cells: Produce mucous (replaced every 10 mins) = protective function containing enzymes and antibodies
3) Basal cells: Produce our olfactory receptor cells

50
Q

Rabies Virus

A

Transmitted through eyes, nose, mouth or through bite and virus targets CNS to cause brain dysfunction and death

51
Q

Who has better olfactory acuity, humans or dogs? Mouse?

A

Humans have the worst acuity

52
Q

Mitral cells

A

Send axons as olfactory tract that projects to olfactory cortex WITHOUT passing through thalamus

53
Q

Anosmia

A

Loss of sense of smell due to blow to the head because of cribiform plate being sensitive to breaking

54
Q

Pathway of olfactory signalling

A
55
Q

Describe the signaling in the olfactory bulb

A

Different receptor cells synapse onto glomerulus (map out odor information) and glomerulus is attached to dendrites of mitral cells

56
Q

T or F: Glomerulus can be modified

A

T

57
Q

Olfactory cortex is found in

A

Primary - temporal lobe
Secondary - frontal lobe

58
Q

What other structures does the olfactory tract project to

A

1) temporal lobe (amygdala) -emotions with smells
2) Hippocampus - learning and memory of smells
3) Orbitofrontal cortex - linking smell to taste and discriminating smells

59
Q

Temporal lobe epilepsy - Aura

A

Someone is about to have a seizure so they will have an aura (smell a certain smell right before their seizure eg. burnt toast) due to location in temporal lobe

60
Q

How does the brain discern smells (3)

A

1) Olfactory population coding: Combination of responses from many smells, not just one receptor cell (eg. smelling onions involves many cells)
2) Olfactory Map: Sensory map and their is spatial representation of particular odours in the bulb (depends also on concentration of odourant)
3) Temporal Coding: Oudor cells fire together in synch (not firing rate) producing intensity and quality of a smell

61
Q

T or F: There is evidence for aromatherapy in rehab

A

F, not yet still trying to learn if smells can affect treatments for cancer and reduce anxiety or stress

62
Q

Chemical senses

A

Taste and smell arise from specific chemical receptors and perception of these senses occurs in cerebral cortex

63
Q

Flavor is perceived by using both

A

taste and smell

64
Q

Gustation and olfaction are strongly linked to our most basic needs. What are these needs.

A

thirst, hunger, emotion, sex, and memory

65
Q

Flavor aversion learning

A

Where we learn to dislike certain foods results and it is stored in associative memory (amygdala)

66
Q

Flavour aversion learning can be used to stop

A

Alcohol or drug addiction or nail biting by making it taste bad

67
Q

What are the 5 basic tastes and where is it sensitive

A
68
Q

Flavour is a combination of

A

taste and smell (eg. onion might taste like apple when nose is plugged)

69
Q

T or F: We also consider what our food feels like

A

T (taste, temperature, and pain)

70
Q

What cranial nerves innervate the tongue

A

1) Facial Nerve: Anterior 2/3 of tongue
2) Glossopharyngeal Nerve: Posterior 1/3 of tongue

71
Q

What nerve innervates the throat (glottis, epiglottis, and pharynx)

A

Vagus nerve

72
Q

Papillae

A

Taste sensitive structures of tongue (contain taste buds)

73
Q

What are the 4 papillae of tongue

A
74
Q

Threshold concentration

A

Each papillae requires a certain stimulus to acquire a specific perception of taste

Higher concentration = papillae become less specific and respond to more types of taste

Lower concentration = papillae become more specialized

75
Q

T or F: Taste receptor cells undergo regeneration every 2 weeks because they undergo regeneration and death constanly

A

T

76
Q

What is a taste receptor cell made of

A
  1. Taste pore
  2. Taste cell
  3. Microvilli
77
Q

Basal Stem cells replace

A

the taste cells

78
Q

Gustatory afferent

A

Synapse at base of taste cells and form gustatory afferent nerve that send info via glossopharyngeal, facial or vagus nerve depending on location of tongue

79
Q

What is the taste signaling pathway

A
80
Q

The taste signaling pathway runs

A

Ipsilaterally

81
Q

The primary gustatory cortex is located in the

A

parietal lobe

82
Q

Lesions to thalamus or gustatory cortex (3rd order neurons) can cause ageusia which is

A

Loss of tase perception

83
Q

Taste pathways are linked to (what other areas of the brain)

A

1) Brainstem regions involved in swallowing, salivation, gagging, vomiting, digestion and respiration
2) Hypothalamus: Involved in hunger and digestion, hormones, and feeding behavior’s
3) Limbic System (Amygdala): Link emotions with eating or how we feel

PT9111 - TEST 3 (16 decks)

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