What is the primary function of the ear?
The ear is specialized for transducing pressure waves in the air into perceptions of sound.
What are the three main sections of the ear?
The outer ear, middle ear, and inner ear.
What are sound waves?
Sound waves are pressure waves that compress and expand air molecules as they travel outward from a vibrating structure.
What is the role of the outer and middle ears?
They funnel and amplify pressure waves from the air.
What is the role of the inner ear?
It converts pressure waves into action potentials.
What structures make up the outer ear?
The auricle and the external acoustic/auditory meatus (ear canal).
What is the function of the auricle?
It is a funnel-shaped flap of cartilage that forms the external ear.
What substance is found in the ear canal and what is its purpose?
Cerumen (earwax), which is secreted by ceruminous glands to trap dirt.
Where do the outer and middle ears meet?
At the tympanic membrane (eardrum), which vibrates in time with pressure waves.
What are the three ossicles (middle ear bones)?
The Malleus (hammer), Incus (anvil), and Stapes (stirrup).
How do the ossicles connect the ear sections?
The malleus attaches to the tympanic membrane, the incus joins the malleus to the stapes, and the stapes attaches to the oval window of the inner ear.
How does sound amplification occur in the middle ear?
The tympanic membrane is much larger than the oval window, so the vibrations of the ossicles amplify the sound wave properties.
What prevents damage from loud sounds?
The tensor tympani muscle (on the malleus) and the stapedius muscle (on the stapes) contract to decrease ossicle vibrations.
What is the Auditory (Eustachian) tube’s function?
It opens to the nasopharynx to allow for the equalization of pressure between the middle ear and the external environment.
What is otitis media?
It is a common ear infection in infants where infection reaches the middle ear from the nose and throat.
What is the bony labyrinth?
A thin shell of bone that surrounds the inner ear.
What is the membranous labyrinth?
A membrane within the bony labyrinth that holds hearing and balance receptors and is filled with endolymph fluid.
What are the three regions of the inner ear?
The Cochlea, Semicircular canals, and Vestibule.
What are the three chambers/ducts of the cochlea?
The vestibular duct (scala vestibuli), the tympanic duct (scala tympani), and the cochlear duct.
What fluid fills the vestibular and tympanic ducts?
Perilymph fluid, which is similar to cerebrospinal fluid.
What fluid fills the cochlear duct?
Endolymph fluid.
What structure contains the hair cells responsible for sound transduction?
The Organ of Corti within the cochlear duct.
What is the process by which an action potential is generated for hearing?
Vibrations of the perilymph distort the basilar membrane and disrupt the position of the hair cells in the Organ of Corti (covered by the tectorial membrane), which generates action potentials.
How does the brain perceive pitch?
Different frequencies of sound waves activate hair cells at different positions within the cochlea.
