ANATOMY LECTURE chapter 17 part 3
otolithic organs
: Saccule and Utricle
Low-frequency or low-pitched sounds
cause the basilar membrane to vibrate near the apex of the cochlea.
high frequency or high-pitched sounds
cause the basilar membrane to vibrate near the base of the cochlea.
hair cells of spiral organ
cells generate nerve impulses in cochlear nerve fibers.
auricle (pinna)
collects sound waves
internal ears
develop first. This also begins about 22 days after fertilization.
cataract
is a loss of transparency of the lens that can lead to blindness
glaucoma
is abnormally high intraocular pressure, due to a buildup of aqueous humor inside the eyeball, which destroys neurons of the retina. It is the second most common cause of blindness (after cataracts), especially in the elderly.
otitis media
is an acute infection of the middle ear, primarily by bacteria. It is characterized by pain, malaise, fever, and reddening and outward bulging of the eardrum, which may rupture unless prompt treatment is given. Children are more susceptible than adults.
deafness sensorineural conduction
is significant or total hearing loss. It is classified as ___ (caused by impairment of the cochlear or cochlear branch of the vestibulocochlear nerve) or ____ (caused by impairment of the external and middle ear mechanisms for transmitting sounds to the cochlea).
equilibrium
The ear also contains receptors for ____.
tinnitus vestibular imbalance
(ringing in the ears) and vestibular imbalance also occur more frequently in the elderly.
external, middle, internal
The ear is divided into 3 regions: the_____, ____, _____
sound waves
result from the alternate compression and decompression of air molecules.
presbycusis
By about age 60, approximately 25% of individuals experience a noticeable hearing loss. Age associated loss is called
semicircular ducts
Contain cristae, site of hair cells for dynamic equilibrium.; detect rotational acceleration or deceleration
basilar membrane
Differences in pitch are related to differences in the width and stiffness of the ___ ____ and sound waves of various frequencies that cause specific regions of the basilar membrane to vibrate more intensely than others.
hair cells of the cochlea
Exposure to loud sounds can damage ______ and possibly lead to deafness.
scala tympani round window
From here, pressure waves travel to the ____ _____ and then to the round window which bulges into the middle ear.
cochlear cochlear nuclei
Nerve impulses from the _____ branch of the vestibulocochlear nerve pass to the ____ ____ in the medulla. Here, most impulses cross to the opposite side and then travel to the midbrain, to the thalamus, and finally to the auditory area of the temporal lobe of the cerebral cortex.
scala vestibuli vestibular membrane endolymph
Pressure waves travel from the ____ _____ to the ____ _____ to the _____ of the cochlear duct.
50
Smell and taste are not affected by aging until around age ___ when the gradual loss of receptors and the slower rate of regeneration have an affect.
vestibulocochlear (VIII) nerve. medulla oblongata
The cochlear nerve fibers form the cochlear branch of the _____ nerve. The axons synapse with neurons in the cochlear nuclei in the ___ ____
optic cups
The distal portion of the optic vesicles forms the
transduction
The ___ of sound vibrations by the ear's sensory receptors into electrical signals is 1000 times faster than the response to light by the eye's photoreceptors.
maculae static equilibrium dynamic equilibrium
The ____ of the utricle and saccule are the sense organs of ____ equilibrium; they also contribute to some aspects of _____ equilibrium
internal (inner) ear (labyrinth) semicircular canals balance and equilibrium
The ______ contains the cochlea which translates vibrations into neural impulses that the brain can interpret as sound, and the _____ _____ that work with the cerebellum for _____ and _____.
hearing
The auricle directs sound waves into the external auditory canal. Sound waves strike the tympanic membrane, causing it to vibrate back and forth. The vibration conducts from the tympanic membrane through the ossicles (through the malleus to the incus and then to the stapes) The stapes moves back and forth, pushing the membrane of the oval window in and out. The movement of the oval window sets up fluid pressure waves in the perilymph of the cochlea (scala vestibuli). Pressure waves in the scala vestibuli are transmitted to the scala tympani and eventually to the round window, causing it to bulge outward into the middle ear. As the pressure waves deform the walls of the scala vestibuli and scala tympani, they push the vestibular membrane back and forth and increase and decrease the pressure of the endolymph inside the cochlear duct. The pressure fluctuations of the endolymph move the basilar membrane slightly, moving the hair cells of the spiral organ against the tectorial membrane; the bending of the hairs produces receptor potentials that lead to the generation of nerve impulses in cochlear nerve fibers. Pressure changes in the scala tympani cause the round window to bulge outward into the middle ear.
pitch
The frequency of a sound vibration is its ____;
presbyopia
The lens begins to lose elasticity and has difficulty focusing on close objects (____) at age 40.
malleus incus stapes oval
The middle ear contains 3 auditory ossicles (smallest bones in the body). They are the __ the ____ which and the _____. Sound vibrations are transmitted from the eardrum through these 3 bones to the ____ window into which the stapes fits.
lens places
The optic vesicles reach the surface ectoderm which thickens to form the
1000 and 4000
The sounds heard most acutely by human ears are from sources that vibrate at frequencies between ____ and _____ Hertz (Hz; cycles per minute).
otic places
The surface ectoderm thickens to form ___ ____that appear on either side of the hindbrain (rhombencephalon).
semicircular
The three _____ ducts, along with the saccule and utricle maintain dynamic equilibrium.
external
The______ (outer) ear contains the auricle (pinna), external auditory canal and the tympanic membrane (eardrum).
optic grooves
They become the optic vesicles.
true or false
Various pathways between the vestibular nuclei, cerebellum, and cerebrum enable the cerebellum to play a key role in maintaining static and dynamic equilibrium.
stapes oval window cochlea perilymph
Vibrations are transmitted from the ____ through the ____ _____ (whose vibrations are about 20 times more vigorous than those of the tympanic membrane) to the ____ as fluid pressure waves are transmitted into the _____ of the scala vestibuli.
meniere's
___ syndrome is a malfunction of the inner ear that may cause deafness and loss of equilibrium.
cornea
admits and refracts(bends) light
otoacoustic emmissions (OAEs)
are caused by vibrations of the outer hair cells that occur in response to sound waves and to signals from motor neurons.
cochlear implants
are devices that translate sounds into electronic signals that can be interpreted by the brain.
equilibrium
balance
eyes
begin to develop about 22 days after fertilization.
auricle
captures sound
cochlea
can produce sounds called otoacoustic emissions
cochlea
contains a series of fluids, channels, and membranes that transmit vibrations to spiral organ(organ of Corti), the organ of hearing, hair cells in spiral organ produce receptor potentials, which elicit nerve impulses in cochlear branch of vestibulocochlear (viii) nerve
anterior cavity
contains aqueous humor that helps maintain shape of eyeball and supplies oxygen and nutrients to lens and cornea
utricle
contains macula, site of hair cells for static equilibrium (maintenance of body position, mainly the head, relative to force of gravity; detects linear acceleration or deceleration that occurs in a horizontal direction and also head tilt
SACCULE
contains macula, site of hair cells for static equilibrium; detects linear acceleration or deceleration that occurs in a vertical direction
vitreous chamber
contains vitreous body that helps maintain shape of eyeball and keeps retina attached to choroid
hair cells
convert a mechanical force (stimulus) into an electrical signal (receptor potential)
external auditory canal (external auditory meatus)
directs sound waves to eardrum
vestibular branch fibers
enter the brain stem and terminate in the medulla; the remaining fibers enter the cerebellum
auditory tube (eustachian tube)
equalizes air pressure on both sides of tympanic membrane
auditory tube (pharyngotympanic tube, eustachian tube)
extends from the middle ear into the nasopharynx to regulate air pressure in the middle ear.
ectoderm of the forebrain (prosencephalon)
forms the optic grooves
medial geniculate nucleus primary auditory area of the cerebral cortex
impulses travel to the ____ of the thalamus and end in the_____ in the temporal lobe.
cristae
in the semicircular ducts are the primary sense organs of dynamic equilibrium.
vestibular apparatus
includes semicircular ducts, utricle, and saccule, which generate nerve impulses that propagate along the vestibular branch of the vestibulocochlear (VIII) nerve.
static equilibrium
maintenance of the body's position relative to the force of gravity
vibration of basilar membrane
moves the hair cells of the spiral organ (organ of Corti) against the tectorial membrane
optic stalks
optic cups remain attached to the prosencephalon by
otic pits
otic placodes form ___ ____ that pinch off to form otic vesicles.
choroid
provides blood supply and absorbs scattered light
sclera
provides shape and protects inner parts
retina
receives light and converts I t into receptor potentials and nerve impulses. output to brain via axons of ganglion cells, which for optic (II) NERVE
lens
refracts light
iris
regulates the amount of light entering the eye
hair cells
release neurotransmitter, which initiates nerve impulses.
ceruminous glands
secrete cerumen (earwax) to protect the canal and eardrum
ciliary body
secretes aqueous humor and alters shape of lens for near or far vision (accommodation)
tympanic membrane(eardrum)
sound waves cause it to vibrate, which in turn causes malleus to vibrate
basilar membrane
vibrates
retinal diseases
such as macular disease, detached retina and glaucoma (damage to the retina due to increased intraocular pressure) occur more frequently in the elderly.
intensity louder
the greater the ____ (size) of the vibration, the ____ the sound (as measured in decibels, dB).
dynamic equilibrium
the maintenance of the body's position in response to sudden movements such as rotation, acceleration, and deceleration.
auditory ossicles
transit and amplify vibrations Fromm tympanic membrane to oval window
external auditory canal
transmits sound to the eardrum.
true
true or false:Muscles of the iris weaken and react more slowly to light and dark causing elderly people to have difficulty adjusting to changes in lighting.