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What is hearing?
What is a sound wave?
Hearing: perception of the energy carried by sound waves.
Sound waves: alternating waves of air pressure with periods of compression and rarefraction.
What is Pitch?
What is the range of frequencies audible to humans?
- Pitch: the frequency of sound waves.
- It is measured in cycles per second (Hz)
Humans: can hear in the range between 20-20kHz.
What is loudness?
- Loudness: our interpretation of sound intensity.
- Function of: wave amplitude.
Measured in decibels.
Does the small size of the external ear affect hearing?
does the middle ear cavity continue to grow during early childhood?
The chain of ossicles have reached adult dimensions and rigidity by birth. True or false
Name the composition of the Auricle, and ear lobe, what lines the ear to produce wax, what limits the ear canal?
- Auricle: elastic composition
- Ear lobe: fat
- Ceruminous glands line the ear cahal and produce wax.
- The structure which limits the ear canal is the tempanic membrane.
Where in the temporal bone does the middle ear sit?
The ear sits on the petrous part of the temporal bone.
The middle ear is lined with a mucus membrane. True or false?
True. the middle ear is lined with a mucus membrane.
What three bones comprise the middle ear. These bones are the reason we are able to chew and hear at the same time.
- The ossicles comprise the middle ear.
- These bones are: Malleus, incus and stapes.
This tube links the middle ear to the pharynx. It usually lies flat, but if opened, it allows equalization of pressure between the middle ear and the throat.
What is Otiits Media?
Otitis media is ear inflammation where infections in the throat can travel up and burst the ear drum.
Sound waves lose or gain energy when they're transferred from air to liquid?
- Lose energy.
- Fortunately, ossicles help with the process of maintain the sound wave energy and use a process called Impedence Matching, to match the air-->liquid sound waves.
Name the shape of the different ossicles, where they're attached and their significance.
Malleus: looks like a hammer, is attached to the tembanic membrane, and incus.
Incus: in between the malleus and the stapes.
Stapes: looks like a stirrup. It's foot plate is attached to the oval window of the inner ear.
The inner ear the "organ of hearing" is also called the labrynth, it is filled with lymph fluid. It's enclosed in the petrous portion of the temporal bone. What are the three regions of the inner ear?
- Three regions are:
- 1. chochlea
- 2. semicircular canals.
- 3. vestibule.
The outside chamber where the inner is enclosed is called?
What is this chamber filled with?
- Bony labrynth.
- It is filled with perilymph.
The chamber which sits inside the bony labrynth is called?
What is it filled with?
The chamber which sids inside the bony labrynth is called the membranous labrynth.
It is filled with endolymph.
Cochlea is involved in hearing. It contains the oval window where the stapes hits against and initiates lymph waves.
It's main organ is the Organ of Corti. What is the purpose of the organ of corti?
The basilar membrane of the cochlear duct has receptor cells with hair embedded in rigid tectoral gel membrane, and the vibrations pull hairs which synapse with sensory fibers of cochlear nerve and set off electrical signal to CN 8
Describe the process of sound transmission through the ear. There are 6 steps.
- 1. Sound waves in the inner ear canal strike the tympanic membrane (eardrum) and become vibrations.
- 2. The sound wave energy is transferred to the ossicles of the middle ear, which also vibrate.
- 3. the vibration of stape's footplate against the oval window of the cochlea are converted into fluid waves within the vestibular duct (perilymph).
- 4. Fluid waves push on the membrane of the cochlear duct (endolymph), activating sensory hair cell receptors.
- 5. Fluid waves energy transfers across the cochlear duct (endolymph) and into the tympanic duct (perilymph) and is dissipated at the round window.
- 6. Activated hair cells within the cochlear duct (endolymph) create action potentials in the sensory neurons of the cochlear nerve.
Which three fluid filled compartments comprise the cochlea?
- 1. Perilymph: fills the tempanic duct and the vestibular duct, which are continuous.The perilymph is comparable to plasma.
- 2. Endolymph: fills the cochlear duct, and resembels the intracellular fluid with high K.
The cochlear duct contains the organ of Corti. This organ contains the hair cells covered with stereocilia. Where does the organ of corti rest?
What are the long stereocilia of hair cells embedded in?
The organ of corti rests on the basilar membrane.
The tectorial membrane is where the longest stereocilia of the hair cells are embedded in. The hair cells initiate a neural impulse by brushing against the tempanic membrane.
The organ of corti has a basalar membrane with hair cells. What are the other types of cells present?
- supporting cells:
- Deiter's cells, Hansen's cells, Claudius cells, inner pillar cells and outer pillar cells.