Physiology of Balance, Taste and Smell Flashcards Preview

Theme 2: Sensory Inputs and Motor Outputs > Physiology of Balance, Taste and Smell > Flashcards

Flashcards in Physiology of Balance, Taste and Smell Deck (17)
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1
Q

Semi circular canals

-How many are there?

A

6 altogether(3 in each ear)

Detects rotation of the head
-L+R lateral, L anterior + R posterior, R anterior + L posterior functionally paired

  • Canals connect to ampulla
  • ampulla embedded in a cupula
2
Q

Otolith organs

-functional divisions

A

To detect tilt and acceleration

  • the utricle- detects movement in the horizontal plane
  • the saccule, which detects movement in the vertical plane.

Within the utricle and saccule, hair cells detect movement when crystals of calcium carbonate shift in response to it, leading to movement in the layers and displacement of hair cells.

3
Q

Mechanism of semicircular canals firing

A

Endolymph movement in the semi-central canals moves the axis of sensory hair cells

-This affects the frequency at which AP fire (CN8)

4
Q

Type I vestibular hair cells

-function

A
  • Less common
  • Surrounded by an afferent nerve calyx
  • hair cells are not directly contacted by efferent nerve fibres
  • signal/detect broad range of movements
5
Q

Type II vestibular hair cells

A
  • Most common
  • receive both afferent and efferent innervation
  • more sensitive
6
Q

Nystagmus

  • Physiological
  • Pathological
A

Physiological-
slow eye movements followed by fast ones during continuous head rotation

Pathological- Spontaneous
Rapid side to side eye movements in the absence of head movements
-due to damage to semicircular canal (lack of firing)

7
Q

Causes of vestibular disorders

A
Ear infection
Head injury 
Whiplash
Ageing
Certain drugs, e.g. (gentamicin) –
8
Q

Olfactory tranduction

A
  1. Odorant molecule binds to receptor cell
  2. release of cAMP and opening channels
  3. Na+ and Ca2+ influx-leads to AP
  4. Opening of Cl- channels
9
Q

Hyposmia and anosmia

A

reduced ability or lack of smell and ability to detect odours

10
Q

Mechanisms of taste tranduction

-salt

A

purely passive

depends on the equilibrium potential for Na+ ions across the taste receptors

11
Q

Mechanisms of taste tranduction

-sour

A

H+ ions close K+ channels
via cAMP
leads to depolarisation

can be direct or indirect

12
Q

Mechanisms of taste tranduction

-sweet

A

cAMP as second messenger

closes K+ channels

13
Q

Mechanisms of taste tranduction

-bitter and umami

A

second-messenger induced increase in intracellular Ca2+ in the receptors. The Ca2+ increase leads to neurotransmitter release

14
Q

Causes of taste disorders

A

URTI

head injury

poor oral hygiene

15
Q

Central pathways of the gustatory system

A

Signals travels via CN 7, 9 and 10
Terminate on neurons on the solitary tract in medulla
travel to thalamus
gustatory cortex/orbitofrontal cortex

16
Q

What are the 2 distinct portions of the middle ear?

A
  1. vestibular portion (semicircular canals for balance)

2. Auditory (cochlear)

17
Q

Describe the anatomy of the vestibular portion of the inner ear

A

3 semicircular canals
which are perpendicular to one another

each canal has a swelling at the end called the ampulla

there are 2 membranous sacs in the middle called the utricle and saccule