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Year 2 NSB > Physiology of Balance, Taste and Smell > Flashcards

Physiology of Balance, Taste and Smell Flashcards

1
Q

What are the 2 functions of the vestibular system?

A
  • balance

- spatial awareness

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2
Q

What does otolith mean?

1 - greek for ear
2 - greek for ear stone
3 - greek for hearing loss
4 - greek for heavy

A

2 - greek for ear stone

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3
Q

Otolith is greek for ear stone. What are the otoliths in the ears?

1 - Ca2+ carbonate sits on top of a gelatinous matrix in the macula of utricle and saccula
2 - Ca2+ carbonate that sits between the utricle and saccula
3 - Ca2+ carbonate acts as a gateway between vestibule and cochlea systems
4 - Ca2+ carbonate sits in the ampulla of the semi-circular canals

A

1 - Ca2+ carbonate sits on top of a gelatinous matrix in the macula of utricle

  • horizontal movements = macula of utricle
  • vertical movements = macula of saccule
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4
Q

What 2 parts of the vestibular system that contain otoliths?

1 - utricle and ampulla
2 - utricle and scale vestibule
3 - saccule and utricle
4 - ampulla and scale vestibule

A

3 - saccule and utricle

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5
Q

Why are the semi-circular canals arranged at 90 degrees to one another?

A
  • to allow 3 dimensional awareness
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6
Q

Which cranial nerve supplies the vestibular system?

A
  • cranial nerve VIII (8) vestibulocochlear nerve

- vestibular branch

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7
Q

What is endolymph?

1 - fluid in bony labyrinth high in K+
2 - fluid in bony labyrinth high in Na+
3 - fluid in membranous labyrinth high in K+
4 - fluid in membranous labyrinth high in Na+

A

3 - fluid in membranous labyrinth high in K+

  • clear fluid located in the membranous labyrinth of the inner ear
  • contains high K+ (140 mEq/L) and low Na+ concentration (15 mEq/L)
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8
Q

What is static equilibrium in relation to body movement?

A
  • when the body is not moving
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9
Q

The saccule and utricle contain a macula, which is filled with sensory mechanoreceptors that are supported by epithelial cells. What are these mechanoreceptors located in the macula called?

1 - oliths
2 - ampulla
3 - hair cells
4 - follicular cells

A

3 - hair cells

- type I and type II

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10
Q

The saccule and utricle are at aprox 90 degrees to one another. Why is this important?

A
  • hair cells are orientated in multiple directions
  • allows detection of head tilt in any direction
  • utricle macula = horizontal plane pointing up remember the boys name HUgh
  • saccule macula = vertical plane pointing out remember Very Small
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11
Q

The hair cells contain cilia that are able to detect horizontal (utricle) and vertical (saccule) acceleration. There are 2 types of cilia, one of which is much larger than the others, what are they both called?

1- stereocilia and epicillia
2 - stereocilia and macucillia
3 - kiniocillia and stereocilia
4 - kiniocillia and large kiniocillia

A

3 - kiniocillia and stereocilia

  • kiniocillia = 1 large in each hair cell
  • stereocilia = mulitple of these in each hair cell
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12
Q

The otolith organs contained within the utricle and saccule contain type I and II hair cells that are able to detect movement in the macula. What are the hair cells embedded in?

1 - mucus
2 - gelatinous matrix
3 - columnar epithelial cells
4 - ear wax

A

2 - gelatinous matrix

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13
Q

The utricle macula contains hair cells in the horizontal plane pointing up. What type of motion are the hair cells of the utricle able to detect?

A
  • linear acceleration in a horizontal plane
  • head tilt (left, right, forward)
  • like driving a car, sudden break and the head moves forward
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14
Q

The saccule macula contains hair cells in the vertical plane pointing up. What type of motion are the hair cells of the utricle able to detect?

A
  • vertical linear acceleration/deceleration

- moving up and down

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15
Q

Label the image of the macula below using the names below:

  • cilia
  • supporting cells
  • vestibular nerve axons
  • gelatinous matrix
  • hair cell
  • otoliths
A 
1 = otoliths
2 = gelatinous matrix
3 = cilia 
4 = hair cell
5 = supporting cells
6 = vestibular nerve axons
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16
Q

The gelatinous matrix of the otolith cells contains otoliths on its surface. What are otoliths?

A
  • calcium carbonate stones

- when movement happens these cause gel matrix to move in a specific direction

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17
Q

The gelatinous matrix of the otolith cells contains otoliths on its surface which are heavy calcium carbonate stones. Why are these important in being able to detect movement in the macule?

A
  • as we accelerate/decelerate the stones are heavy and pull the gelatinous matrix in a specific direction
  • pulling of the gelatinous matrix is detected by hair cells
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18
Q

Each hair cell in the vestibular system have cilia like projections and one large projection at the end, what are these called?

1- stereocilia and epicillia
2 - stereocilia and macucillia
3 - kiniocillia and stereocilia
4 - kiniocillia and large kiniocillia

A

3 - kiniocillia and stereocilia

  • small = sterocilia
  • large = kinocilium
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19
Q

In addition to the multiple sterocilia (small) and the singular kinocilium (large) on hair cells in the vestibular system there is something in between each sterocilia (small) and the singular kinocilium (large). What is this call and what is its purpose?

A
  • mechanotransducotors

- connected to spring-gated ion channels

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20
Q

In addition to the multiple sterocilia (small) and the singular kinocilium (large) on hair cells in the vestibular system there is something in-between each sterocilia (small) and the singular kinocilium (large) called tip links. When there is movement the otoliths that are on top of the gelatinous membrane drag the gelatinous membrane. As they drag the gelatinous membrane the hair cells inside also move. When the hair cells detect movement the tip links come into closer contact with the adjacent sterocilia and kinocilium. When this occurs what happens?

1 - tip links open mechanically gated Na+ channels
2 - tip links open mechanically gated Ca2+ channels
3 - tip links open mechanically gated Mg+ channels
4 - tip links open mechanically gated K+ channels

A

4 - tip links open mechanically gated K+ channels

- increased K+ causes depolarisation

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21
Q

In addition to the multiple sterocilia (small) and the singular kinocilium (large) on hair cells in the vestibular system there is something in-between each sterocilia (small) and the singular kinocilium (large) called tip links. When the hair cells detect movement the tip links come into closer contact with the adjacent sterocilia and kinocilium. When this occurs tip links open mechanically gated K+ channels and increased K+ causes depolarisation. What then happens at the base of the hair cell?

A
  • depolarisation of the hair cell causes Ca2+ release at the bottom of the hair cells
  • Ca2+ causes vesicles containing glutamate to fuse with membrane, releasing glutamate
  • glutamate (stored in vesicles) is released into synaptic space
  • glutamate binds to glutamate receptors and depolarises the axon, sending a signal to the brain
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22
Q

When our heads are in a stationary position we are constantly generating action potentials to tell the brain about our head position. However, if we change position and move towards or away from the kinocilium, do the action potentials increase or decrease?

A
  • towards = increased action potentials

- away = decreased action potentials

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23
Q

There are 3 semi-circular canals which are continuations of the utricle. What are the 3 positions (names) of the canals?

1 - superior, posterior and inferior
2 - superior, inferior and lateral
3 - anterior, posterior and lateral
4 - lateral, medial and inferior

A

3 - anterior, posterior and lateral

  • anterior (like handle on a handbag)
  • posterior (like handle on a mug)
  • lateral (like a shelf draw pulling out)

Together they provide 3 dimensional information

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24
Q

The semicircular canals are continuations of the utricle, and therefore contain the same fluid, which is called what, endolymph or perilymph?

A
  • endolymph

- high in K+ and low in Na+

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25
Q

The semicircular canals are continuations of the utricle, and therefore contain the same fluid, called endolymph. There is also an enlarged portion at the end of each of the semi-circular canals (so 3 in total), called what?

1 - macula
2 - canaliculi
3 - fossa
4 - ampulla

A

4 - ampulla

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26
Q

In the ampulla is the crista ampullaris, which is the sensory organ that is able to detect rotation and angular acceleration and deceleration. What is contained within the crista ampullaris?

1 - cisterna
2 - hair cells type I and II
3 - Ca2+ channels
4 - otoliths

A

2 - hair cells type I and II

- a gelatinous mass called the capula that covers hair cells

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27
Q

In the ampulla is the crista ampullaris, which is the sensory organ that is able to detect rotation and angular acceleration and deceleration. Within the crista ampullaris are hair cells type I and II covered in a gelatinous mass called the cupula. Each hair cell is the same as those contained within the saccula and utricle, meaning they have lots of sterovilli, one kinocilium and tip links that connect sterovilli and the kinocilium. What happens if the hair cells are stimulated and the sterovilli and the kinocilium move towards a stimulus?

A
  • tip links open mechanically gated K+ channels
  • K+ causes depolarisation
  • depolarisation causes Ca2+ channels to open
  • Ca2+ causes the release of glutamate into synaptic space
  • glutamate binds to receptors causing action potential to be sent to the brain via cranial nerve VIII (8) the vestibulocochlear
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28
Q

Once the semi-circular afferent nerves have been stimulated they will travel along cranial nerve VIII (8) vestibulocochlear nerve. Where is the first place they will synapse?

A
  • superior and medial vestibular nuclei
  • group of cell bodies from vestibule branch of CN VIII (8) the vestibulocochlear nerve
  • located in the lower pons and upper medulla
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29
Q

How many parts of the vestibular nuclei (VN) are there?

A 
- 4 parts located in lower pons and upper medulla
1 - superior VN
2 - lateral VN
3 - medial VN
4 - inferior VN
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30
Q

Once the utricle macula stimulate the afferent nerves they will travel along cranial nerve VIII (8) vestibulocochlear nerve to where?

A
  • lateral vestibular nuclei
  • lateral because they detect horizontal/lateral motion
  • located in the lower pons and upper medulla
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31
Q

Once the saccule macula stimulate the afferent nerves they will travel along cranial nerve VIII (8) vestibulocochlear nerve to where?

A
  • lateral and inferior vestibular nuclei
  • inferior as they detect vertical movements
  • located in the lower pons and upper medulla
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32
Q

Once the saccule macula stimulate the afferent nerves they will travel along cranial nerve VIII (8) vestibulocochlear nerve to the inferior and lateral vestibular nuclei (VN). Once here which cranial nerves do the inferior and lateral VN then go onto stimulate?

A
  • to the cerebellum from inferior VN
33
Q

Once the semicircular canals stimulate the afferent nerves they will travel along cranial nerve VIII (8) vestibulocochlear nerve to the superior and medial vestibular nuclei (VN). Once here which cranial nerves do the inferior and lateral VN then go onto stimulate?

A
  • the abducens nuclei of cranial nerve VI (6) abducens nerve

- the occulomotor nuclei of cranial nerve III (3) occulomotor nerve

34
Q

Projections of the 4 regions of the vestibular nuclei (inferior, superior, lateral and medial) are able to innervate which cranial nerves?

1 - CNs I, II and III
2 - CNs II, III and IV
3 - CNs III, IV and VI
4 - CNs IV, VI and X

A

3 - CNs III, IV and VI

  • cranial nerve III (3) (oculomotor nerve)
  • cranila nerve IV (4) (trochlear nerve)
  • cranial nerve VI (6) (abducens nerve)
  • contribute towards coordinating the eye, neck and trunk movement.
35
Q

Projections of the 4 regions of the vestibular nuclei (inferior, superior, lateral and medial) are able to innervate cranial nerves III (3) (oculomotor nerve), IV (4) (trochlear nerve) and VI (6) (abducens nerve), contributing towards coordinating the eye, neck and trunk movement. How are these then transported into posture and muscle tone to help balance and move?

1 - travel to motor cortex for processing
2 - travel to frontal cortex for processing
3 - travel down descending tracts
4 - travels to the cerebellum

A

3 - via descending pathways

36
Q

What is nystagmus?

A
  • an involuntary rhythmic side-to-side, up and down or circular motion of the eyes that occurs with a variety of conditions
37
Q

When looking at the semi-circular canals of the vestibular system, which are filled with endolymph, if we move our head and look to the right, does the endolymph move in the same direction to the right or to the left?

A
  • opposite

- so endolymph moves to the left

38
Q

When we turn our head to look to the right the endolymph within the lateral semi-circular canals of the vestibular system will move in the opposite direction. How does this link with out eye position?

A
  • the right vestibular nuclei decussate to left hemisphere
  • the efferent signal innervates the abducens nuclei of cranial nerve VI (6) (abducens nerve)
  • cranial nerve VI (6) signals the left lateral rectus muscle to contract and eye moves to the left
39
Q

When we turn our head to look to the right the endolymph within the lateral semi-circular canals of the vestibular system will move in the opposite direction. The right vestibular nuclei decussates to the left hemisphere and the efferent signal innervates the abducens nuclei of cranial nerve VI (6) (abducens nerve) and contracts the left lateral rectus muscle to contract and eye moves to the left. How does this also contribute to the right eye?

A
  • interneurons from the abducens muscle decussation to right side of hemisphere
  • signals for the right cranial nerve III (3) the occulomotor nerve to contract the right medial rectus
40
Q

Nystagmus has 2 phases, what are they?

A
  • slow phase = slow eye movement in opposite direction

- fast phase = rapid eye movement to jump back to same direction

41
Q

Nystagmus has 2 phases:

  • slow phase = slow eye movement in opposite direction
  • fast phase = rapid eye movement to jump back to same direction

If nystagmus occurs in the absence of head movement, what can this indicate?

A
  • damage or a lesion to the vestibular system
42
Q

The caloric test can be used to test the vestibular system. How is this test performed?

A
  • ice cold or warm water or air is irrigated into the external auditory canal
  • temperature difference between the body and fluid creates a convective current in the endolymph of the semicircular canal
  • hot and cold water produce currents in opposite directions and therefore a horizontal nystagmus in opposite directions
43
Q

The caloric test can be used to test the vestibular system. Ice cold or warm water or air is irrigated into the external auditory canal of the patient. The temperature difference between the body and fluid creates a convective current in the endolymph of the semicircular canal. The hot and cold water produce currents in opposite directions and therefore a horizontal nystagmus in opposite directions. When hot or cold water is used what nystagmus will this cause?

A
  • hot water = movement of head to left, but the eyes move to the right causing a right eye nystagmus
  • cold water = movement of head to right, but the eyes move to the left causing a left eye nystagmus
44
Q

In a healthy person using a caloric test, if the water is injected to the left ear the following occurs:

  • cold = head moves left and eyes move to right
  • hot = head moves right and eyes move to left side

If the above does not happen, what does this indicate?

A
  • damage or lesion to the vestibular system
45
Q

Vertigo is a dysfunction of the vestibular system. What happens to cause vertigo?

A
  • accumulation of debris from otolithic membrane to the ampulla
  • sensitivity is increased to angular movement, affecting balance
  • causes nausea and/or vomiting
46
Q

Dysfunction of the vestibular system can be caused by some other basic things such as?

A
  • ear infection
  • trauma
  • inflammation of the membranous labyrinth
  • ototoxity caused by drugs
47
Q

Meniere’s disease is a condition that affects the inner ear, and ultimately the vestibular system. What is meniere’s disease?

A
  • accumulation of endolymph due to poor drainage
  • damage to hair cells has also been observed, possibly due to endolymph oedema (fluid retention).
  • vertigo that is intermittent and relapsing.
  • possible hearing distortion or tinnitus
48
Q

Which cranial nerve supplies the olfactory system (sense of smell)?

A
  • cranial nerve I (1)

- olfactory nerve

49
Q

In the nasal cavity where are the olfactory receptors located?

A
  • top of the nasal cavity
50
Q

What is the average life span of olfactory receptors?

1 - 10-20 days
2 - 20-30 days
3 - 30-60 days
4 - >100 days

A

3 - 30-60 days

51
Q

Olfactory receptors are bipolar. Where do their 2 projections travel to?

A

1 - project into nasal cavity as and give off olfactory hairs (cilia)
2 - project into axons that form mini olfactory nerves that ultimately become cranial nerve I (1) olfactory nerve

52
Q

The axons that project from the bipolar olfactory receptors merge and synapse at the glomerulus, where they will synapse with the 2nd order neurons. What is the area where this is contained within called?

1 - cribiform place
2 - olfactory bulb
3 - nasal concha
4 - junction with sphenoid bone

A

2 - olfactory bulb

- resembles a bulb

53
Q

Olfactory receptors (ORs), also known as odorant receptors, are chemoreceptors, what are chemoreceptors?

A
  • specialised cell groups responsible for acquiring information about the chemical environment
  • chemical environment is conveyed into neurons.
54
Q

In the olfactory system the dendrites from the olfactory receptors create cillia and protrude out into the nasal cavity to bind with chemicals that are associated with smells. The cilia sit in a mucous layer, what is the purpose of this layer?

A
  • smell molecules get trapped in the mucosal layer

- allows for binding to cilia

55
Q

Olfactory receptors only have a life span of around 30-60 days. How are these receptors replaced?

1 - stem cells in the basal epithelium
2 - cells undergo metaplasia
3 - cilia shed but are replaced with fresh cilia to detect smells
4 - they are not replaced, just change

A

1 - stem cells in the basal epithelium

- form of plasticity and regeneration

56
Q

Are the axons of the olfactory receptors myelinated?

A
  • no
57
Q

What type of receptor do smell molecules bind with on the olfactory receptors?

1 - GPCR (Gai)
2 - GPCR (G-olfactory protein)
3 - tyrosine kinase receptors
4 - ligand gated ion channels

A

2 - GPCR (G-olfactory protein)

- adenylyl cyclase increases cAMP and phosphorylation

58
Q

Smell molecules bind with on the olfactory receptors, which are G protein coupled receptors, specially G-olfactory protein. Once bound, what is the intracellular pathway?

A
  • Na+ and Ca2+ channels open and enter the cell
  • Ca2+ opens Cl- and Cl- leaves the cell
  • both increase charge causing depolarisation
  • the receptor then fires and sends an action potential to the olfactory bulb
59
Q

Once an action potential has been stimulated from the olfactory receptors they synapse with the 2nd order neurons in the olfactory bulb. What neurotransmitter is released here?

1 - dopamine
2 - serotonin
3 - glutamate
4 - acetylcholine

A

3 - glutamate

60
Q

Once the olfactory neurons leave the olfactory bulb where do they travel to in the brain?

1 - piriform cortex in the temporal lobe (primary)
2 - somatosensory cortex
3 - occipital cortex
4 - cerebellum

A

1 - piriform cortex in the temporal lobe (primary)
- can also signal limbic system (thalamus, hypthalamus and amygdala), which is why some smells make us feel a certain way

61
Q

What does anosmia and hyposmia mean?

A
  • ansomia = loss of smell (a = lack of and somia = smell)

- hyposmia = reduced smell

62
Q

What are some common causes of ansomia (loss of smell) and hyposmia (reduced smell)?

A
  • head injury
  • covid-19
  • nasal polyps
  • age
  • smoking/chemical inhalation
63
Q

Cacosmia (Phantosmia) is an olfactory disorder, what is this?

A
  • cac = bad/ugly (think caca for poo) and osmia = smell
  • olfactory hallucination of unpleasant smells
  • affects the temporal lobe
  • think caca is poo in french
64
Q

Which common neurodegenerative disease can affect the olfactory system?

1 - Alzheimers
2 - Parkinsons disease
3 - Dementia
4 - SLE

A

2 - Parkinsons disease

65
Q

What is the gustatory system?

A
  • gustare is latin and means ‘to taste’

- so the tastinh system

66
Q

What are the 5 basic senses of taste:

A 
1 - sweet
2 - bitter
3 - salty
4 - sour
5 - umami (Japanese for pleasant savoury taste)
67
Q

Are their specific regions in the tongue that can detect certain tastes, or is the tongue able to taste everything?

A
  • everything
68
Q

Which cranial nerve innervates the tongue muscles?

A
  • cranial nerve XII (12)

- hypoglossal nerve

69
Q

The taste receptors are able to enter the taste receptors that can then innervate the afferent nerves. Which cranial nerves receive afferent projections relating to taste?

1 - CN V, VI and VII
2 - CN VII, VIII and IX
3 - CN VII, IX and X

A

3 - CN VII, IX and X

  • cranial nerve X (10) the vagus nerve
  • cranial nerve IX (9) the glossopharyngeal nerve
  • cranial nerve VII (7) the facial nerve
70
Q

Taste receptors are arranged like orange slices, what type of receptor are these?

1 - chemoreceptors
2 - mechanoreceptors

A

2 - chemoreceptors

  • meaning they can detect changes in chemicals
  • same as olfactory
71
Q

When our taste receptors bind to a chemical, what happens to trigger the release of a neurotransmitter and an action potential that travels to the cranial nerves?

A
  • depending on the taste (salty, sour etc) affects the ions that flow into the taste receptor
  • salty causes an influx of Na+, followed by Ca2+
  • sour causes an influx of H+, followed by Ca2+
  • Ca2+ influx allows neurotransmitters to be released into synaptic space and bind with their respective receptors
72
Q

What are the most common neurotransmitters that are released following the binding of a taste molecule to a taste receptor?

A

1 - serotonin
2 - noradrenalin
3 - acetylcholine
4 - GABA

73
Q

Within our tongues we have taste receptors 1 and 2. In taste receptors 1, which are for salty and sour tastes, what cation is released into the cell to initiate depolarisation?

A
  • salty = Na+ followed by Ca2+

- sour = H+ followed by Ca2+

74
Q

Within our tongues we have taste receptors 1 and 2. In taste receptors 2, which are for sweet and bitter tastes, what is released into the cell to initiate depolarisation?

A
  • sweet = GPCR Gas pathway
  • bitter = GPCR Gaq pathway
  • both increase Ca2+
75
Q

Which nerves project the afferent signals relating to taste to the gustatory cortex?

A
  • chorda tympani (cranial nerve VII (7)) facial nerve provides anterior 2/3rds
  • cranial nerve IX (9) the glossopharyngeal nerve provides posterior 1/3rd
  • cranial nerve X (10) the vagus nerve
76
Q

The chorda tympani (arises from the mastoid segment of cranial nerve VII (7) the facial nerve) can be affected during ear surgery, why and what does this cause?

A
  • runs through the middle ear
  • any error in surgery or trauma to the ear can cause dysgeusia (perception of taste is altered)
  • this nerve provided the anterior 2/3rds of the tongue
77
Q

Dysgeusia can be caused by an error in surgery or trauma to the ear canal. What is dysgeusia?

A
  • change in perception of taste
  • dys = dysfunction
  • geusia = taste
78
Q

What is hypogeusia?

A
  • diminished sense of taste
  • hypo = low
  • geusia = taste

Year 2 NSB (53 decks)

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