Ageing special sensory system

Question 1

What senses constitute the special senses?

Answer 1

Hearing, Balance, Vision, Taste and Olfaction

Question 2

Which two physiological systems undergo age-related changes in ALL individuals:

Answer 2

Hearing and vision

Question 3

What percentage of adults and over 60s experience hearing loss?

Answer 3

20% of adults and 75% of over 60s have mild hearing loss

Question 4

Why are auditory and visual decline not much of a problem in modern society?

Answer 4

~ hearing aids increase volume and change pitch of sound

~ contact lenses and glasses improve vision

Question 5

Why are age related changes in olfaction important?

Answer 5

Effect both taste and smellas they are linked

Question 6

What is amplitude?

Answer 6

the amplitude of waves

Question 7

What is pitch?

Answer 7

wave frequency?

Question 8

What is he human range of pitch?

Answer 8

1000-4000Hz

Question 9

What is the purpose and structure of the middle ear?

Answer 9

Middle ear bones
(ossicles: malleus,
incus & stapes)
amplify & transfer
sound to the oval
window

Question 10

What is the function of the inner ear?

Answer 10

The inner ear has hair cell

receptors for hearing in the cochlea and equilibrium in semi-circular canals (balance)

Question 11

Which part of the ear protects against loud noises and how?

Answer 11

• Middle ear reflexes protect against loud noises but respond
poorly to sudden loud sounds (eg gun shot), risking damage
• The tensor tympani muscle & stapedius muscle both contract in
response to loud sounds

Question 12

What is the cause of presbycusis?

Answer 12

Reduced movement of the tympanic membrane (ear drum) and middle ear bones

Question 13

How do AGEs contribute to presbycucis?

Answer 13

~ tendons attached to the ossicles become cross-linked due
to Advanced Glycation End products (AGEs) and stiffen
~ this reduces sensitivity to loudness and pitch
~ it is a non-enzymatic process which gets worse with age

Question 14

What is prebycusis?

Answer 14

Loss of hearing in old age

Question 15

What are possible causes of presbycusis

Answer 15

~ can be caused by conductive problem in the middle ear
~ usually caused by loss of hair cells or stereocilia therefore less neurotransmitter is released in response to sound which decreases sensation of loudness and pitch

Question 16

What age related changes occur to the auditory cortex and auditory nerves?

Answer 16

~ neuron losses in ageing sensory pathways reduces hearing
~ blood vessel thickening reduces blood flow and hearing
~ cochlear implants may help

Question 17

What can cause sensorineural hearing loss?

Answer 17

Ototoxic drugs such as aminoglycoside antibiotics

Question 18

What is the neuronal sequence of events to perceive sound

Answer 18

The nerves go to thalamus, then
the auditory cortex
~ superior temporal gyrus
~ left has hearing and pitch dominance
~ right has music dominance
Many cross to opposite side & ascend via the inferior colliculus
~ role in acoustic reflexes
~ direction detection
1st order neurones synapse in
medulla (cochlear nucleus)
Afferent fibres form the cochlear
branch of the vestibulocochlear
nerve enter the brain stem

Question 19

What is the vestibular apparatus?

Answer 19

~ contains 3 semicircular canals at right angles to each
other which respond to movement 3 planes
• Semicircular canals transduce rotational movement in 3
directions using cupula hair cells located in ampullla
~ the Utricle and Saccule transduce linear acceleration
using otolith (calcium carbonate crystals) linked hair cells

Question 20

What age related changes occur to the vestibular apparatus?

Answer 20

40% less vestibular nerve
fibres the by age 80
18,000 ↓ to 11,000 by 80
• Age related changes affect balance, equilibrium & dizziness in
14 – 30% of the over 60s mainly due to hair cell loss

Question 21

What age related changes occur to vestibular hair cells?

Answer 21

• Vestibular hair cell degeneration occurs with age

* By age 90 vestibular function can fall by 40%

Question 22

How are utricles and saccules effected by ageing?

Answer 22

33000 normal, reduction of 20% by age of 80

Saccules contain about 19000 hair cells decreasing to 14000 in old age

Question 23

What wavelengths are detected by he retina?

Answer 23

Wavelengths between 400-700nm

Question 24

What age related changes occur to vision?

Answer 24

Age-related changes reduce acuity, sensitivity, adaption

thresholds and nerve number

Question 25

What is presbyopia?

Answer 25

inability of the lens to recoil, from a spherical shape, to

increase it’s refractive power to focus on near objects

Question 26

How do AGEs contribute to presbyopia?

Answer 26

Collagen cross links stiffen the lens

Question 27

Why does vision decline irreparably as we age?

Answer 27

• Terminally differentiated
cells in the lens are not
relaced when they die
~ lens damage is not
repaired as we age
• A slight decrease in
smooth muscle cell
number occurs in the
ciliary body

Question 28

what is the purpose of the lens changing shape?

Answer 28

to make adjustments for far and near objects

Question 29

Why does ageing reduce the ability to focus on an object

Answer 29

elasticity reduction makes changing the lens shape less effective

Question 30

What type of retinal cells reduce in number as we age?

Answer 30

Ganglion cells and optic nerve axons

Question 31

What is cataracts?

Answer 31

a cataract is an opaque lens caused by photo-oxidation and a lack of lens repair as cells die
it is crystalin proteins in the lens denature

Question 32

what are age related frequency for cataracts?

Answer 32

0. 7% of 50-59s;
1. 2% of 60-69s;
2. 5% of 70-79s
3. 8% of 80+

Question 33

what are age related frequency for Glycoma?

Answer 33

0. 1% of 50-59s;
1. 2% of 60-69s;
2. 3% of 70-79s
3. 7% of 80+

Question 34

What is glycoma?

Answer 34

Glaucoma is a group of disorders in which intraocular pressure
causes optic neuropathy and to blindness

Question 35

what are age related frequencies for Macular degeneration?

Answer 35

<0.1% of 50-59s;

0. 05% of 60-69s;
1. 15% of 70-79s
2. 5% of 80+

Question 36

Name 3 general facts regarding taste buds

Answer 36

~ taste receptor cells die within about 10 days and are
continually replaced by new receptor cells
~ they are chemoreceptors found within taste buds
~ each taste bud contains 40 - 150 receptor cells

Question 37

at what age does taste bud number decline?

Answer 37

about 50

Question 38

What is loss of olfactory sense called?

Answer 38

anosmia

Question 39

what percentage 80+ year olds have major olfactory impairment

Answer 39

75%