EAR

Question 1

What are the three parts of the ear

Answer 1

Outer ear
Inner ear
Middle ear

Question 2

What is the outer ear comprised of and its function

Answer 2

• Pinna- hearing O
  collects sound waves and channels them into the ear canal
• External acoustic meatus
• tympanic membrane

Question 3

What is the middle ear comprised of and its function

Answer 3

air-filled tympanic cavity, three auditory ossicles, and tympanic membrane

Question 4

What is the inner ear and its function

Answer 4

cochlea (the organ of hearing) and the vestibular system (the organ of balance).

Question 5

How does mechanically gated transduction work

Answer 5

Movements affect stretch-sensitive ion channels at the tip of the sensory hairs

Tip links connecting cilia open the K+ channels

Leads to depolarisation

Voltage-gated Ca2+ channels open

Influx of Ca2+ causes release of neurotransmitter by exocytosis

Question 6

How do you know if have vestibular problem

Answer 6

Head tilt towards lesion

Question 7

What are the two parts of the vestibular organ

Answer 7

Semicircular canals- give dynamic information, fluid filled and say how head it moving
Otolith organs- static information.

Question 8

What are the two otolith organs

Answer 8

Utricle
Saccule

Question 9

What does the saccule sense

Answer 9

gathers sensory information to orient the body in space. It primarily gathers information about linear movement in the vertical plane, including the force due to gravity.
Stationary

Question 10

How do the otolith organs

Answer 10

Each organ has a sheet of hair cells, the macula, whose cilia are embedded in a gelatinous mass, just like the semicircular canals. Unlike the canals, however, this gel has small crystals of calcium carbonate embedded in it, called otoliths. The otoliths provide the inertia, so that when movement to one side occurs, the otolith–gel mass causes the hair cells to deviate

Question 11

What does the utricle do

Answer 11

linear accelerations and head-tilts in the horizontal plane
Detects horizontal movement

Question 12

What are the semicircular canals filled with

Answer 12

Endolymph

Question 13

How do the canals determine head movement

Answer 13

There are 3 canals, each one is in a different plane
Flow within the endolymph matches head rotation in the same plane as the canal.
Movement of endolymph causes cilla to move, which results in release of neurotransmitters

Question 14

Why do you get a head and body tilt with vestibular problems

Answer 14

On side of lesion:
The excitatory impulse to the extensor muscles is failed
So you just get flexor
Also muscle isn’t functioning as anti gravity

Question 15

What is the floccunolodular lobe

Answer 15

Part of the cerebellum

receives input from, and functions in conjunction with, the vestibular system to regulate equilibrium/balance and posture

Question 16

What does the floccunolodular lobe structure look like

Answer 16

Ipselateral projection

Question 17

What is hearing

Answer 17

Hearing is the neural perception of sound energy

Question 18

How is sound generated

Answer 18

All objects vibrating in air or water generate sound

Causes compression and rarefaction of molecules in the environment, creating areas of increased and decreased pressure

Question 19

What is the wavelength of sound

Answer 19

Distance between areas with maximal pressure

Question 20

What is sound frequency

Answer 20

Pitch

Question 21

What is sound pressure

Answer 21

Volume/ amplitude

Question 22

What is the pinna made from

Answer 22

Elastic cartilage and skin

Question 23

What CN innervates the muscle of the pinna

Answer 23

CN 7

Question 24

What is the structure of the external acoustic meatus like

Answer 24

L shapes tube ending in tympanic membrane
Contains sebaceous glands that produce earwax, and hairs to act as a barrier to dust, insects etc.

Question 25

What is the structure of the tympanic membrane lie,

Answer 25

Covered by epithelium on the outside Covered by mucus membrane on the inside

Question 26

What is the function of the pinna and external acoustic meatus

Answer 26

Pinna and external auditory meatus act as funnel to collect sound wave vibrations and direct to the eardrum

Question 27

What is the function of the tympanic membrane

Answer 27

When sound waves reach your eardrum, they cause the membrane to vibrate, which then travels to the middle ear Also acts as barrier to bacteria getting into the inner ear

Question 28

What is the function of the middle ear

Answer 28

The middle ear is an air-filled cavity in the temporal bone containing ossicles transferring tympanic membrane vibrations to the inner ear

Question 29

What are the three ossicles

Answer 29

malleus, incus, and stapes

Question 30

What is the function of ossicles

Answer 30

Acts as a series of levers to transmit sound wave vibrations The stapes is attached to the membrane covering the oval window of the cochlear

Question 31

What does the middle ear consist of

Answer 31

Ossicles Tympanic bulla

Question 32

What is the Eustachian tube/ guttural pouch and its function

Answer 32

Auditory tube Connects middle ear to pharynx Narrow and normally closed Purpose is to equalise the air pressure on the two sides of the tympanic membrane

Question 33

How is sound waves transmitted to inner ear

Answer 33

To achieve this, it increases pressure and reduces amplitude of vibrations through the ossicles Stapes pushes on fluid in inner ear

Question 34

How many canals are there in the cochlear and what are they called

Answer 34

3 Outer, middle, inner

Question 35

What is each canal filled with

Answer 35

Upper and lower canals- perilymph Middle canal- endolymph

Question 36

What is the difference between peri lymph and endolymph

Answer 36

Endolymph is higher in K+ and more positive electro potential

Question 37

Where are the sensory cells on the cochlear

Answer 37

Basilar membrane

Question 38

How does the cochlear work

Answer 38

When the oval window is compressed by the ossicles it creates wave that travel through the fluid of the cochlear These waves cause the basilar membrane to move too Causes hair cells and stereocilia to move for transduction of stimulus

Question 39

How is frequency of sound discriminated

Answer 39

High frequency waves have maximum amplitudes near round window Low frequency cause membrane to vibrate with maximum amplitude near tip of cochlear

Question 40

How is the vestibular cochlear nerve connected to organ

Answer 40

Communicates with hair cells and enters brainstem just under cerebellum Afferent from organ of Corti Efferent to organ of Corti (tensions membrane)

Question 41

What is the caudal colliculus

Answer 41

4 bumps that form of the root of the midbrain

Question 42

What does the caudal colliculus do

Answer 42

Auditory information co-ordinates head/ear/neck muscles to orientate the animal’s head towards sound source

Question 43

How does the brain determine the direction of sound

Answer 43

based on differences in arrival time between both ears Lower sound pressure at furthest ear (sound shadow) Mobile external ears help with location of sound from behind/infront

Question 44

What are the two different types of hearing loss

Answer 44

Conduction Sensation

Question 45

What are the causes of conduction hearing loss

Answer 45

Otitis externa (wax in ear canal)- sound waves can’t get down Otitis media (pus/ fluid in ear)- oscilles cant vibrate Rupture of tympanic membrane

Question 46

What are some problems with sensation hearing loss

Answer 46

Damaged hair cells – loud or continuous sound Ototoxic drugs (e.g. streptomycin) Inherited conditions

Question 47

Where does conduction hearing loss occur

Answer 47

External to internal acoustic meatus

Question 48

Where does sensation hearing loss occur

Answer 48

Inner ear

Question 49

How does BAER work

Answer 49

Each ear is stimulated separately by a click stimuli Accumulated action potential from the cochlea via the cochlear nerve can be measured as auditory evoked potential Sedation or anaesthesia required to avoid artefacts Can be used to determine brain health in a coma