Physiology of Hearing Flashcards
How does sound move through the air?
As sound waves
What is a sound wave?
Vibrations of molecules causing compression and rarefaction of the air particles
What is frequency?
The number of compression & rarefaction (waves) in a second.
What is the range of human hearing?
20 Hz - 20,000 Hz
What causes hearing loss - high sound pressure or low sound pressure?
High sound pressure
What is sound pressure?
Localised pressure caused by a sound wave travelling through and increasing / decreasing atmospheric pressure
What is sound pressure measured in?
Decibels
How does the hearing system hear sounds?
It converts vibrational waves (sound) to electrical neuronal impulses via mechanoreceptors in the ear.
What type of channels do mechanoreceptors contain? Where are these channels found on the mechanoreceptor?
They contain cation channels - found in the membrane of the receptors.
How do mechanoreceptors work roughly?
The vibrational sensation causes the sensory receptor in the membrane to open causing an influx of cations, causing depolarisation, thus allowing for the release of NTs OR generation of AP as a result.
What are the three parts of the outer ear?
Pinna
External auditory canal
Tympanic membrane (ear drum)
Where are the auditory ossicles found?
Middle ear
Where is the cochlea found?
Inner ear
Name the three auditory ossicles
Malleus
Incus
Stapes
What can happen to the ossicles as we get older to cause hearing loss?
They can fuse a bit, losing their ability to vibrate as much
Which ossicle is attached to the tympanic membrane?
Malleus
Which ossicle is attached to the oval window?
Stapes
How is the stapes attached to the oval window?
Annular ligament - connective tissue
What is the purpose of the middle ear?
It converts sound waves from the outer wave to fluid waves in the inner ear.
What senses is the inner ear responsible for?
Audition (hearing)
Balance
What is the cochlea made of?
Bony labyrinth & membranous labyrinth
What is the bony labyrinth filled with?
Perilymph
What is the membranous labyrinth filled with?
Endolymph?
How do perilymph and endolymph differ?
Different ion concentrations
Perilymph = high Na and low K+
Endolymph = low Na and high K+
What are the three parts of the cochlear canal?
Scala vestibuli (upper)
Scala media (middle)
Scala tympani (lower)
What does the Scala vestibuli contain?
Perilymph
Where does the Scala vestibuli end?
Oval window
What dos the Scala media contain?
Endolymph + Organ of Corti
What does the Scala tympani contain?
Perilymph
Where does the Scala tympani end?
In the round window
What does the helicotrema do?
Allows communication between the Scala vestibuli and Scala tympani