Hearing And Equilibrium Flashcards
The external ear
Consists of pinna and the ear canal, sealed at its end by tympanic membrane (eardrum)
Middle ear
Just beyond the ear drum, an air filled space connected to the pharynx by the Eustachian tube
The inner ear
Contains the sensors; cochlea and vestibular apparatus
What is the cochlea important for
Hearing
What is the vestibular apparatus important for
Equilibrium
What exactly is sound
Pressure waves
Where is the pressure high in pressure waves? Where is the pressure low?
High in the peaks, low in the troughs
Pitch
The frequency (number of wave peaks per second)
What is the sound range for human ears
16-20,000 Hz- 10 octaves
Where is acuity highest in human hearing
1000-3000 Hz
Amplitude
The pressure difference between peak and trough
Main factor that determines our perception of loudness- the larger the amplitude the louder the sound
T/F. Loudness depends entirely on amplitude
False, it depends on amplitude and frequency
What does the eardrum separate
The outer ear from the middle ear
Describe the path of sound vibrations
The eardrum will vibrate the malleus bone, moving the incus, which moves the stapes, pushing against the oval window
What are the smallest bones in the body
The ossicles, three bones in the ear, the malleus, incus, and stapes which act as a lever system carrying vibrations from the eardrum to the smaller oval window
Where are the receptor cells in the ear
Cochlea
Describe the path of sound vibrations from the oval window to the cochlea and back to the middle ear
- The ossicles vibrate the oval window
- Wave energy passes through the cochlea and exits from round window to the middle ear
- Some of the wave energy will travel through the helicatrima, into the tympanic duct while others take a short cut through cochlea duct with auditory cells (hair cells)
The cochlear duct contains the ______
Organ of corti (contains auditory receptors)
Organ of Corti
Sits on the basilar membrane and under the tectorial membrane
Contains auditory receptor cells- mechanoreceptors- they are epithelial cells and contain around 20,000 per cochlea
Stereocilia
Each hair cell contains 50-100 stiff hair cells which extend into the tectorial membrane.
They bend when waves in perilymph deform the basilar and tectorial membranes
When do hair cells depolarize
When the cilia bend toward the longest cilium, exciting a neuron and will release a neurotransmitter- activating primary sensory neuron
Axons of these neurons form the auditory nerve (cochlear nerve)- cranial nerve 8
When do hair cells hyperpolarized
When its cilia bend away, releasing less transmitter and does not cause any excitation
Where is the membrane narrow and stiff?where is wider and more flexible
It is narrow near the round and oval window. Wider and flexible at the helicotrema
Fill in the blank.
high-frequency waves maximally displace the membrane at the _____ end
Oval window end
