hearing and equilibrium

Question 1

what is hearing

Answer 1

Auditory system

response to vibrating air molecules

Question 2

what is equilibrium

Answer 2

Vestibular system

sense of motion & balance

Question 3

what is sound

Answer 3

Pressure wave

zone of compression (air particles close together) & zone of rarefaction (air particles spread apart)

Question 4

what is pitch (high or low)

Answer 4

frequency of vibration [Hz]

Question 5

what is loudness

Answer 5

amplitude of vibration [Db]

Question 6

what is pitch measured in

Answer 6

hertz (Hz)

Question 7

what is loudness measured in

Answer 7

decibels (Db)

Question 8

explain the outer ear

Answer 8

fleshy auricle/pinna; auditory canal

secretions + dead cells
- earwax

Question 9

explain the middle ear

Answer 9

eardrum; 3 smallest bones & 2 smallest skeletal muscles of body

contains auditory ossicles:
- Malleus [hammer]
- Incus [anvil]
- Stapes [stirrup]

Question 10

explain the inner ear

Answer 10

bony labyrinth contains:
Organs of equilibrium
Organ of hearing
- cochlea

Question 11

in the anatomy of the ear, the eustachian tube leads to what

Answer 11

to nasopharynx (superior portion of pharynx)

Question 12

where does ear wax come from

Answer 12

from ceruminous glands in outer ear canal

Question 13

what is the eustachian tube

Answer 13

(auditory tube)
is an air circulating tube which goes from back of nose, near the adenoids, to the air space in the middle ear

Question 14

what does an air pressure equalization tube do

Answer 14

keep middle ear pressure the same as outside pressure

Question 15

explain the cochlea in the inner ear

Answer 15

Snail-like spiral with 3 fluid filled chambers

Vibration form a nerve impulse via organ of corti.

Question 16

explain the organ of corti

Answer 16

Contains outer hair cells with hairs
- stereocilia

On top of which rests gelatinous tectorial membrane

Base of cell synapses with nerve fibres

Question 17

explain how the organ of corti allows us to hear

Answer 17

Sound bends hairs (via vibrating membranes & lymph)
to
Depolarise cell
to
Induces action potential
to
Conducted to CNS
to
Translated in cerebral cortex as ‘sound’

Question 18

The cochlea is filled with what and what doe sthis do

Answer 18

a fluid

moves in response to the vibrations from theoval window.

As the fluid moves, 25,000 nerve endings are set into motion.

These nerve endings transform the vibrations into electrical impulses, these travel along the eighth cranial nerve to the brain
- auditory nerve

Question 19

describe the Frequency Response of Basilar Membrane of Cochlea

Answer 19

Low pitch in centre, high pitch as enter cochlea:

Question 20

explain the vestibular system

Answer 20

Human Labyrinth, from the left ear. It contains i) the cochlea (yellow), which is the peripheral organ of our auditory system; ii) the semicircular canals (brown), which transduce rotational movements; and iii) the otoliths (in the grey pouches), which transduce linear accelerations. The light blue pouch is the endolymphatic sac and contains only fluid.

Question 21

name the semi circular canals part of the vestibular apparatus

Answer 21

anterior
posterior
horizontal

and these are all on the lateral part of the ear

Question 22

name the otolith organs canals part of the vestibular apparatus

Answer 22

utricle
saccule
cochlea

and these are all medial to the ear

Question 23

semicircular ducts are stimulated by what

Answer 23

by rotation of head in different planes

Question 24

semi circular ducts are filled with what

Answer 24

endolymph

Question 25

what does each of the semicircular ducts have at one end

Answer 25

dilated sac at one end called:
Ampulla

Question 26

describe the structure and cells of semicircular ducts sac’s

Answer 26

With mound of hair cells with stereocilia embeded in gelatinous cupula membrane; all called crista ampullaris

Question 27

how do semicircular canals move

Answer 27

by cupula being pushed over as head turns
this is called: Crista ampullaris

Question 28

what does equilibrium provide us with

Answer 28

co-ordination of balance

Question 29

explain the vestibular apparatus in terms of equilibrium

Answer 29

Contain structures and receptors for equilibrium

3 semicircular canals/ducts:
- movement e.g., rotation

2 chambers:
- Otolith organs; saccule & utricle
— position, acceleration or deceleration

Question 30

what are the 2 types of equilibrium called

Answer 30

static
dynamic

Question 31

what is static equilibrium

Answer 31

head orientation when stationary

Question 32

what is dynamic equilibrium

Answer 32

motion or acceleration

Question 33

explain the chambers of the vestibular

Answer 33

Each chamber has patch of hair cells:
Macula
- 1 vertical = macula sacculi
- 1 horizontal = macula utriculi

With stereocilia tips embedded in gelatinous otolithic membrane

Weighted with otoliths
- calcium carbonate-protein crystals

Question 34

what do otoliths do

Answer 34

bend hairs

Question 35

name the 2 auditory neural pathways

Answer 35

peripheral auditory canal (outer, middle and inner ear)

central auditory system (auditory cortex, medial geniculate body (parts of brain), inferior colliculus (within chest), cochlear nucleus, superior olivary complex(stomach and pelvis area))

Question 36

explain the CNS pathway for equilibrium

Answer 36

in vestibular apparatus:
vestibular branch of bestibulocochlear nerve (Viii)

then to vestibular nuclei of medulla and then to somatic motor neurons controlling eye movement

or

from vestibular apparatus to cerebellum then reticular formation, then to thalamus, and then to the cerebral cortex in the brain