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.