Sensory disorders

Question 1

function of the external, middle and inner ear

Answer 1

external : funnels sound waves, sound localisation, prevent entrance of foreign bodies

middle : sound amplification and pressure equalization

inner :
- cochlea : transforms waves into nervous signal
- semicircular tubes : balance (eye movements)

Question 2

what happens in vertigo ?

Answer 2

vestibular problem or in brain -> sensation of motion without motion -> nausea, sweating

Question 3

what is the first type of hearing impairement and the 4 main mechanisms

Answer 3

conductive impairement -> problem in outer or middle ear -> sound can’t reach cochlea

1) obstruction
2) mass loading (middle ear effusion)
3) stiffness effect (otosclerosis)
4) discontinuity (ossicular disruption)

Question 4

describe the obstruction and stiffness mechanisms in more detail

Answer 4

obstruction :
- most commonly ear wax (cerumen)
- do not irrigate organic foreign bodies (would swell)
- immobilize living insects

otosclerosis :
- inflammatory disease of bone
- treatment : replace the ossicles with implants

Question 5

what is the second type of hearing impairement ? is it reversible ? Give three possible causes

Answer 5

sensorineural impairement -> cochlea or nerve problem -> usually irreversible

1) ototoxic medication : antibiotics, aspirin, …

2) trauma
- loud sounds >85dB
- head trauma

3) presbycusis (older people) -> affects high pitched sounds

Question 6

what is otitis media and the mechanism ? why does it happen more often in children ?

Answer 6

It is an inflammation of the middle ear. There is an upper respiratory tract infection that causes liquid to accumulate in the eustachian tube -> negative pressure in middle ear.

Kids have a shorter tube and it’s more horizontal.

Question 7

symptoms and treatment of acute and chronic otitis media

Answer 7

1) acute :
- pain, fever, rupture of tympanic membrane
- anti-inflammatory drugs, sometimes antibiotics

2) chronic (>12 weeks)
- adhesions in middle ear, retraction of tympanic membrane, scarring
- debris removal and ventilation tubes

Question 8

what are the 3 things that healthy vision requires ?

Answer 8

• formation of image on retina
• stimulation of rods and cones
• conduction of nerve impluses to brain

Question 9

describe the structure of the eye

Answer 9

• cornea (clear)
• iris (eye color)
• lens -> focuses light on retina
• retina : light transformed into nerve impulses

Question 10

explain the aqueous and vitrous humour

Answer 10

anterior chamber : aqeuous humor filled from ciliary body, flows around and drained through canal of schlemm -> regulates eye pressure

posterior chamber : behind lens, contains vitrous humor

Question 11

explain the different things present on the retina (4)

Answer 11

rods -> black and white vision
cones -> color and visual acuity
macula -> mainly cones
optic disc -> blind spot

Question 12

name the 4 errors of refraction

Answer 12

1) myopia (nearsightedness) : rays focus before the retina -> concave lens

2) hyperopia : rays focus after the retina -> convex lens

3) presbyopia : loss of accommodative capacity -> reading glasses

4) astigmatism : irregular curvature of cornea -> distorted image and multiple focal points -> glasses

Question 13

what is strabismus ? how do you treat it ?

Answer 13

cross-eyedness (squint) because the muscles of one eye are weaker. Brain gets two images. -> patching of good eye, glasses, surgery

Question 14

what is amblyopia ? therapy ?

Answer 14

poor vision, even with proper optical correction -> patching, blurring of vision

Question 15

what is cataract ? treatment ?

Answer 15

clouding, opacity of the lens -> removal / replacement of the lens

Question 16

explain 3 retinopathies

Answer 16

1) retinal detachment
- caused by accumulation of fluid, mechanical forces, or shrinkage of vitrous humor
- blurred vision, flashes

2) diabetic retinopathy : caused by impaired blood flow (treat it by controlling the diabetes)

3) macula degeneration : unknown causes, areas of central vision loss become larger and darker

Question 17

what is glaucoma ? what are the 2 types ?

Answer 17

progressive loss of vision due to increaed intraocular pressure (blood supply to retina is decreased)

1) chronic open angle
- the angle where the canal is, is bigger
- treatment : increasage drainage, decrease pressure, constrict pupil

2) acute angle-closure
- very small angle where the canal is -> drainage of liquid is blocked
- rapid onset by darkened room (pupil gets big)