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1st yr-Med 2022-2023 > BMC L10 > Flashcards

BMC L10 Flashcards

1
Q

How do we hear?

A

Sound is captured by the pinna (auricle)
Travels through external acoustic meatus
VIBRATES tympanic membrane
This compresses molecules in medium, molecules in medium they recoil when pressure (sound) is removed

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2
Q

Describe the anatomy of the ear?

A

Diargam L10

Pinna (auricle) (EXTERNAL EAR)
External acoustic meatus (EXTERNAL EAR)
Tympanic membrane (MIDDLE EAR)
Pharyngeal tympanic tube (INNER EAR)

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3
Q

Describe the transmission of sound

A

This is the route of sound waves through the inner ear.

  1. Sound waves vibrate the tympanic membrane
  2. Vibrates auditory ossicles (Maleus, incus, Stapes).
  3. They then amplify the pressure
  4. The pressure created by stapes pushes onto oval window, causing perilymph fluid in the scala vestibuli to move
  5. If sound is in hearing range, sound waves travel through cochlear duct, vibrating basilar membrane, causing hairs to be pushed onto inner hair cells, exciting the hair cells
  6. If the sound is not in the hearing range (below), sound waves travel through helicotrema and no hair cells are excited
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4
Q

State the parts of the external ear

A

Auricle
Externl auditory meatus

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5
Q

State the parts of the middle ear

A

Tympanic membrane
Auditory ossicles - maleus
- incus
- stapes

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6
Q

State the parts of the inner ear

A

Oval window, round window
Cochlear duct / scala media
Scala vestibuli
Scala tympani
Vestibular membrane
Basilar membrane
Perilymph
Endolpymh
Auditory tube (pharyngotympanic tube)
Helicotrema

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7
Q

Explain how the basilar membrane can act as a frequency spectrum analyser

A

Sound waves of different frequencies cross / vibrate the basilar membrane at different locations

For example, at the base (oval window), fibres are short and stiff, and vibrate with high frequency sound waves

At the apex, fibres are long and floppy and vibrate with low frequency sound waves

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8
Q

State the function of the organ of corti

A

Tranduces pressure waves (sounf waves) into APs

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9
Q

Where is the organ of corti located

A

Spiral organ of corti

Basilar membrane

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10
Q

How does the organ of corti transduce pressure waves into APs

A

Basilar membrane vibrates
Tectorial membrane does not, but moves radially
Differnce in motion
Deflects stereocillia
Generates AP

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11
Q

Spiral ganglion

A

Afferent fibres of cochlear nerve coil around the base of hair cells

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12
Q

How is loudness detected?

A

Stronger, more frequent vibrations to basilar membrane
More deflection of hair cells
More excitation of hair cells
Therefore, more action potentials sent from inner hair cells to brain

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13
Q

What is localisation of sound?

A

Detecting the location of the source of sound by both ears

Depends on

  1. Timing sound waves reach both ears
  2. Relative intensity of sound waves reaching both ears
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14
Q

Where is the primary auditory cortex located?

A

Temporal lobe

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15
Q

What is the function of the primary auditory cortex?

A

Certain cells in primary auditory cortex respond to sound waves of certain frequencies - tonopically organised

DETECTS

Repition
Intensity
Pitch
Duration

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16
Q

What is the function of the secondary auditory cortex?

A

Higher analysis:

Rythmic
Harmonic
Melodic

17
Q

State the two muscles associated with the auditory ossicles

A

2 striated muscles:

  1. Stapedius muscle - attached to stapes
  2. Tensor tympani muscle - attached to malleus
18
Q

State the function of the stapedius and tensor tympani striated muscles

A

Reduce amplification of loud sounds
Protects ear from damage

19
Q

State the two types of hair cells present in the organ of corti and their function

A

Inner hair cells: Less numerous, densely innervated, 10 sensory axons per each hair cell
Function: send APs to brain
SYNAPSE WITH AFFERENT NEURONES

Outer hair cells: More numerous, arranged in 3 rows, sparsely innervated, 1 sensory axon per sevral hair cells
Function: Alter the mechanical composition of basilar membrane to dampen / amplify sound
SYNAPSE WITH EFFERENT NEURONES

20
Q

State 3 hearing loss disorders

A

Sociocusis - noise e.g. traffic
Presbycusis - age, heredity, oxidative stress, inflammatory conditions, sensorineural hearing disorder - loss of hair cells
Nosocusis
-oxotoxic drugs (aspirin)
-diabetes
-hypertension

21
Q

State 4 homeostatic imbalances of hearing

A

Conduction deafness
Sensorineural daefness
Tinnitus
Menier’s Syndrome

22
Q

Conduction deafness

A

Blocked sound conduction of fluids in the internal ear

Caused by

-Impacted ear wax
-Perforated ear drums
-Otosclerosis of ossicles

23
Q

Sensorineural deafness

A

Damage to neuaral structures (from cochlear hair cells to auditory cortical cells)

24
Q

Tinnitus

A

Ringing / clicking sound in ears in absence of auditory stimuli

Cause

Cochlear nerve degeneration
Inflammation of middle / internal ears
Side effects of aspirin

25
Q

Menier’s syndrome

A

Disorder of inner ear (cochlear / semicircular canals)

Leads to vertigo, nausea, vomiting

26
Q

State the role of vision in balance

A

Vertical references
Perception of motion in visual field

Importance:

-Navigation + object avoidance

27
Q

What is the issue of constant use of vision in balance?

A

Constant reliance of vision in balance - we become dependent

This leads to visual vertigo

28
Q

Balance

A

Line of gravity occurs within base of support

29
Q

State the role of postural control

A

MAINTANANCE OF POSTURE

Restores line of gravity within base of support, maintains balance, therefore, maintains posture

30
Q

Explain the limits of stability and what happens when limits of stability is exceeded

A

Boundaries in which the body maintains its position without altering base of support

If exceeded, step, stumble, grap external onject to regain balance, if not, you will fall

30
Q

Explain the limits of stability and what happens when limits of stability is exceeded

A

Boundaries in which the body maintains its position without altering base of support

If exceeded, step, stumble, grap external onject to regain balance, if not, you will fall

1st yr-Med 2022-2023 (57 decks)

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