Physiology Of Balance, Smell And Taste

Question 1

Why are the 4 otoliths organs not at right angles?

Answer 1

To enable them to resolve head tilt and linear acceleration in all directions

Question 2

What detects circular rotation?

Answer 2

Semicircular canals

Question 3

Sensory cells of semicircular canals are embedded in?

Answer 3

Cupula (gelatinous), moves with fluid

Question 4

What are the otoliths organs?

Answer 4

Sacculus and utriculus

Question 5

Sensory cells in otoliths are embedded in?

Answer 5

Otoliths, gelatinous sheet covered with heavy crystals of calcium carbonate

Question 6

Vestibular hair cells types?

Answer 6

Type 2- receive both afferent and efferent

Type 1- surrounded by calyx not directly contacted by efferent nerve fibres

Question 7

Nystagmus?

Answer 7

Slow eye movements then fast ones during continuous head rotation, vestibular ocular reflex

Question 8

Spontaneous nystagmus happens when?

Answer 8

Eyes move rhythmically from side to side in the absence of head movements
1 canal is damaged
Net difference between canals even when head is stationary

Question 9

Caloric testing?

Answer 9

Cold water irrigation, eye movements in direction of water.

1. With brainstem intact both eyes move to ear with water.
2. With medial longitudinal fiasciculus lesion, movement of eye only on irrigated side
3. Low brainstem lesion-no response

Question 10

What does warm or cold water do?

Answer 10

Generates current in canal mimic endolymph movement induced by turning head to irrigated side or away from it

Question 11

What does alcohol do in canals?

Answer 11

Creates convection currents, feel as if you are rotating

Question 12

What do currents cause?

Answer 12

Changes in firing rate of vestibular nerve, increased on warm and decreased in cold

Question 13

Vestibular disorder drugs?

Answer 13

Aminoglycoside antibiotics gentamicin, also affects hearing

Question 14

Benign paroxysmal position vertigo?

Answer 14

Otoliths causing contamination of endolymph, vertigo caused by changes in head position

Question 15

Menieres disease?

Answer 15

Progressive hearing loss, tinnitus and vertigo. Excess fluid in inner ear

Question 16

How many odorant receptor proteins?

Answer 16

1000 and in each cell has just one of these

Question 17

Olfactory transduction?

Answer 17

cAMP opens ligand gated ion channels, no selective Na and ca, depolarises cells causing AP.

Ca influx open Cl- channels, causing Cl- to leave cell contributing to depolarisation

Question 18

Hyposmia and anosmia percent?

Answer 18

5-10

Question 19

Umami recognition of?

Answer 19

Amino acids

Question 20

How does sour sensation come about?

Answer 20

H+ closes K+ channels directly or through cAMP, causing depolarisation

Question 21

Sweet sensation happens through?

Answer 21

Second messenger closing K+ channels, depolarising

Question 22

Bitter and umami sensation?

Answer 22

Second messenger induced increase in intracellular Ca, causing neurotransmitter release

Question 23

Gustatory system signalling via?

Answer 23

7th for anterior 2/3 and 9 and 10 for rear 1/3 to nucleus of solaitary tract in brainstem.

Then 2 order neurons project ipsilaterally to ventral posterior nucleus of thalamus.

Then to insula then to orbitofrontal cortex

The parabrachial nuclei of pons sit of second order synapsing, then to hypothamalmic nuclei and amygdala

Question 24

What is the secondary cortical taste area?

Answer 24

Orbitofrontal cortex

Question 25

Some second order neurons synapse to?

Answer 25

Parabrachial nuclei of pons which then project to amygdala and hypothalamus

Question 26

How many taste disorders are smell disorders?

Answer 26

80%

Question 27

Endolymph in the scala media in the cochlea is continuous with what?

Answer 27

Endolymph on the apical surface of the vestibular hair cells

Question 28

What is the left anterior canal paired with?

Answer 28

The righ posterior canal

Question 29

Sensory cells in the ampullae is embedded within?

Answer 29

Cupula

Question 30

Central vestibular pathways?

Answer 30

Vestibular organs to vestibular nuclei/cerebellum then to:

Spinal cord, cerebral cortex, reticular formation, oculomotor nuclei and extra ocular muscles

Question 31

Causes of vestibular disorders?

Answer 31

Head injury
Whiplash
Ageing
Ear infection
Certain drugs e.g aminoglycoside antibiotic

Question 32

Difference between lightheaded and spinning?

Answer 32

Spinning- check vestibular

light-headed- cardiovascular

Question 33

Central pathway of olfactory system?

Answer 33

Olfactory receptors- bulb- tract- entorhinal cortex/olfactory tubercle/pyriform cortex and amygdala

Then that leads to the thalamus, hypothalamus, hippocampus formation, orbitofrontal cortex

Question 34

What are the causes of hyposmia and anosmia?

Answer 34

Upper respiratory tract infection, age, nasal polyps, diabetes, head trauma, high dose radiation at nasal epithelium and drugs

Question 35

Where are circumvallate found?

Answer 35

Back of tongue under the uvula

Question 36

Where are follate?

Answer 36

Side of tongue towards the back

Question 37

Fungiform are found?

Answer 37

Tip of tongue

Question 38

What is a cause of true taste disorders?

Answer 38

Prior upper respiratory tract infections, head injury and poor oral hygiene