Lecture 9 Hear Flashcards
(31 cards)
What is the sequence of ion flow in an action potential?
Na⁺ flows in (depolarisation), K⁺ flows out (repolarisation), then reset
What triggers an action potential?
An influx of positively charged Na⁺ ions into the neuron
What causes repolarisation after an action potential?
K⁺ ions flow out of the neuron
What is the speed of sound wave propagation in air?
Approximately 1,100 km/h
What is the frequency range of human hearing?
30 – 20,000 Hz
What physical process underlies hearing?
Vibration of objects causing air pressure changes (compression and rarefaction)
What is the function of the pinna?
Helps determine the elevation of a sound
What structure converts physical movement into neural signals in the inner ear?
The cochlea
What is the role of the ossicles (malleus, incus, stapes)?
Amplify eardrum vibrations and transmit them to the oval window
What does the stapes push against to initiate cochlear fluid movement?
The oval window
What is the function of the round window?
Bulges outward when oval window is pushed in, allowing fluid to move
What is the basilar membrane?
A membrane inside the cochlea that vibrates in response to sound and supports hair cells
What is the Organ of Corti?
Structure on the middle chamber of the cochlea, composed of the basilar membrane, hair cells, and tectorial membrane
What happens when stereocilia on hair cells bend to the right?
Ion channels open, causing K⁺ and Ca²⁺ influx and neurotransmitter release
What is the first stage of converting physical movement into neural signals?
Bending of hair cells in the cochlea
Which hair cells drive most auditory nerve signals?
Inner hair cells
What is the role of outer hair cells?
convert sound pressure into neural signal
What happens if inner hair cells are damaged?
Hearing is severely impaired or lost
What is the relationship between frequency and position on the basilar membrane?
High frequencies vibrate the base; low frequencies vibrate the apex
What is place coding?
Different positions along the basilar membrane respond to different frequencies
What is the function of spiral ganglion cells?
Transmit frequency-specific auditory signals to the brain
How is sound information transmitted to the brain?
Auditory nerve → Cochlear nuclei → Superior olivary nucleus → Auditory cortex (both side of the brain, first place the brain beginning to process it)
What is tonotopic organisation?
Spatial arrangement where different frequencies are processed at different locations
Where does primary frequency processing occur in the brain?
Primary auditory cortex
