Sound and Hearing

Question 1

what is sound?

Answer 1

• sound is produced when matter is acted upon
• vibration that propagates as an acoustic wave
• sound energy
• produced in many activities (Eg. voice)

Question 2

what are the two properties of sound?

Answer 2

amplitude (loudness) and frequency (pitch)

Question 2

what is the frequency?

Answer 2

• measured in hertz (cycles per second)
• pitch is the frequency of waves in a given amount of time - depends of frequency
• higher pitch - higher frequency
• lower pitch - lower frequency

Question 2

what is amplitude?

Answer 2

• sound pressure level
  -magnitude of sound - loudness
  -measured in decibels - 70 dBA or lower is safe hw 85 dBA or higher can damage your hearing

Question 2

why is hearing useful?

Answer 2

helps us converse with other people, learn by listening, hear music and shows and podcasts and alert us of dangers

Question 3

what are the hearing structures for the outer ear?

Answer 3

pinna - funnel sound energy toward ear
external auditory meatus
tympatic membrane

Question 4

what are the hearing structures for the middle ear?

Answer 4

ossicles - 3 bones in ear
ligaments and muscles

Question 5

what are the hearing structures in the inner ear?

Answer 5

cochlea
auditory nerve

Question 6

when do we do our best hearing?

Answer 6

because of the shape of the ear we do our best hearing face to face - funnel and capture info and magnifies the sound

Question 7

external auditory meatus - description of the structure

Answer 7

• small opening surrounded by cartilage (makes up the pinna)
• medial two thirds are bony
• proximal end is closed at the T.M

Question 8

role of the external auditory meatus

Answer 8

• conducts sound energy from concha to the T.M
• role is resonator- amplify certain pitches/ freq or sound b4 reaching the tympatic membrane

Question 9

tympatic membrane - description of the outer ear structure

Answer 9

• 8-10mm diameter with 3 layers (0.0001m thick)
• “cone of light” via otoscope - see the bottom portion will shine
• used to be labelled the eardrum - now the TM
• boundary bw outer and middle ear

Question 10

tympatic membrane - function of the outer ear structure

Answer 10

• function is that sound energy is funneled in
• hits membrane and causes it to vibrate from sound energy

Question 11

ossicles - structure within the middle ear

Answer 11

• smallest bone in the human body
• extends from human body extending
  from T.M to oval window of cochlea
• 3 ossicles in ear- malleus (hammer), incus (anvil), stapes (stirrup)

Question 12

ossicles - function within the middle ear

Answer 12

amplify the sound energy applied to the T.M to the fluid in the cochlea

Question 13

pharyngotympanic or eustachian tube - structure within the middle ear

Answer 13

• Aka. The auditory tube
• 3.8 cm tube running from middle ear to nasopharynx
• cartilaginous and flexible toward the nasopharynx where it is usually closed

Question 14

pharyngotympanic or eustachian tube - function within the middle ear

Answer 14

• opens occasionally to equalise the pressure in middle ear
• also functions to drainage mucus

Question 15

what part of the ear is the semicircular canal?

Answer 15

inner ear

Question 16

semicircular canal role within inner ear

Answer 16

essential for balance

Question 17

bony labrynth - within the inner ear

Answer 17

• oval window - footbed of the stapes (ossicles), movement on oval window will move fluid called perilymph
• round window - perilymph exerts force on round window, causing it to slightly bulge

Question 18

cochlea - structure

Answer 18

• coil like structure - comes up and down
• filled with perilymph
  
  1. scala vestibuli - spiral up
  2. scala tympani - spiral down

Question 19

cochlea - function / description

Answer 19

• movement of perilymph leads to movement of the basilar membrane
• movement the basilar membrane means hair cells bend which causes action potential to be sent along the cochlea nerve

Question 20

cranial nerve 8 - CNVIII

Answer 20

• auditory nerve - part of cranial nerve VIII
• afferent fibres will carry signal to central nervous system structures that

allow us to:
- converse w other ppl, learn by listening, hear music/podcast - temporal lobe
- moves head toward sound ( brainstem)

Question 21

order of the hearing process

Answer 21

external sound energy, funnelled by the pinna, external auditory meatus, tympanic membrane, amplified through the ossicles, oval window, move perilymph, move hair cells, action potential, CNVIII, Primary auditory cortex

Question 22

auditory perception

Answer 22

- ability to receive, identify and attach meaning to sounds - perception is the ability to interpret info that our senses receive from the environment - interpretation is an active process that depends on our cognitive processes and prior knowledge - relies on the auditory cortex and association nerves - eg. recognise someone via listening to their voice, sirens

Question 23

types of hearing impairments

Answer 23

- conduction deafness - sensorineural deafness - tinnitus - menieres syndrome

Question 24

what is conduction deafness?

Answer 24

- hampers sound conduction to the fluids of the inner ear - eg. impacted ear wax, perforated eardrum, osteosclerosis of the ossicles,

Question 25

sensorineural deafness

Answer 25

damage to the neural structures at any point from the cochlear hair cells to the auditory cortical cells

Question 26

tinnitus

Answer 26

- ringing or clicking sound in the ears in the absence of auditory stimuli - disorder of the cochlea

Question 27

menieres syndrome

Answer 27

- entire labrynth disorder - affects cochlea and semicircular canals - causes vertigo, nausea, vomiting

Question 28

structural types of neurons

Answer 28

unipolar bipolar multipolar

Question 29

unipolar

Answer 29

- one process of the cell body: mainly sensory neurons - neuron that is unipolar has an axon that extends into dendrites

Question 30

bipolar

Answer 30

- cell body positioned in the middle of the neuron - has both an axon and a dendrite extending from the stoma - two processes of the cell body mainly special sensory neurons

Question 31

multipolar

Answer 31

- two or more dendrites and one axon - many processes of the cell body: mainly motor

Question 32

functional types of neurons

Answer 32

sensory, motor and interneuron

Question 33

sensory neurons

Answer 33

carry sensory info from receptors to CNS eg. touch of skin, taste

Question 34

motor neurons

Answer 34

carry action potential from CNS to the PNS to effect the muscles

Question 35

interneurons

Answer 35

in CNS only to facilitate efficient communication bw neurons

Question 36

What is the structural difference bw a neuron classified as myelinated compared to unmyelinated?

Answer 36

- myelinated axon have Schwann cells tightly coiled around them axons have larger loose Schwann cells in unmyelinated neurons around a group of axons

Question 37

What is the functional difference bw a neuron classified as myelinated compared to unmyelinated?

Answer 37

speed of transmission of nerve impulses is high in myelinated nerve fibres. hw unmyelinated nerve fibres don't have myelin insulations, tf the speed of transmission of nerve impulses is slow

Question 38

Describe similarities and differences bw spinal nerves and cranial nerve

Answer 38

- similar - both nerves, part of the PNS, can be motor/sensory OR both -differences - spinal nerves connect body structures (eg. bicep) to the CNS whereas Cranial nerves connect the head and neck structures to Brain and Brain Stem

Question 39

Where are the spinal and cranial nerves in the body?

Answer 39

- spinal nerve - in the spinal cord -cranial nerve - in the head

Question 40

Explain the difference between nerve fascicles and peripheral nerves

Answer 40

- peripheral nerves are formed by bundles of fascicles grouped by epineurium - nerve fascicles are surrounded by another layer of connective tissue - perineurium