Chapter 19: Special Senses Part I (Equilibrium and Hearing) SYDNEY Flashcards
what is stimuli
changes in environment
what is sensation
conscious awareness
5 general senses
-temperature
-pain
-touch
-stretch
-pressure
5 special senses
-taste
-smell
-vision
-equilibrium
-hearing
what are receptors?
-initiate nerve impulses
-type of transducer
definition of transducer
change one type of energy into another
2 types of receptors
-tonic receptors
-phasic receptors
process of tonic receptor
continuous response
process of phasic receptor
-detect new stimulus/change
-adaptation
definition of adaptation
acclimating to changes that persist
what is the lateral head?
temporal bone
parts of the ear
-external ear
-middle ear
-inner ear
parts of the external ear
-auricle
-external acoustic meatus
external ear is a skin-covered, primarily cartilaginous structure called _____
auricle (or pinna)
what is the external acoustic meatus?
bony tube in ear that extends medially and slightly superiorly from the lateral surface of the head
type of glands in external acoustic meatus
ceruminous glands
the makeup of earwax
cerumin + dead skin
where does the external acoustic meatus terminate?
at the tympanic membrane
funnel-shaped epithelial sheet that is the partition between the external and middle ear
tympanic membrane (or eardrum)
parts of the middle ear
-auditory ear ossicles
-auditory (eustachian) tube
what are the auditory ossicles?
tympanic cavity of the middle ear houses the three smallest bones of the body
features of the auditory ear ossicles
-amplify sound waves
-oval window (inner ear)
-suspended by ligaments
what are the 3 smallest bones in middles ear ossicles?
-malleus
-incus
-stapes
where is the malleus located?
-attached to the medial surface of the tympanic membrane
shape of malleus
resembles a large hammer
features of incus
-shape: resembles an incus
-middle auditory ossicle
features of stapes
-shape: resembles a stirrup on a saddle
-footplate in oval window
what is responsible for amplifying sound waves?
the auditory ossicles
size of tympanic membrane compared to footplate of stapes
tympanic membrane 20x larger than footplate of stapes
significance of the size of the tympanic membrane
sounds transmitted across the middle ear are amplified more than 20-fold, and able to detect very faint sounds
how does the tympanic cavity maintain an open connection with the atmosphere?
auditory (eustachian) tube
what does the auditory (eustachian) tube do?
equalize pressure
2 tiny skeletal muscles of the middle ear
-stapedius
-tensor tympani
which of the middle ear ossicles is the stapedius located in?
stapes
which of the middle ear ossicles is the tensor tympani located in?
malleus
what do the skeletal muscles (stapedius and tensor tympani) do?
-dampen loud sounds
-protect receptors in inner ear
what is otitis media?
an infection where there is fluid in the middle ear
features of otitis media
-pressure, pain
-common in children
-risk reduces after age 5
why is otitis media more common in children?
they have shorter/flatter auditory tubes
spaces or cavities in the inner ear
bony labryinth
membrane-lined, fluid-filled tubes and spaces within the bony labyrinth
membranous labyrinth
space between the outer walls of the bony labyrinth and the membranous labyrinth is filled with a fluid called ___________
perilymph
composition of perilymph
extracellular fluid
membranous labyrinth contains a unique fluid called ______
endolymph
composition of endolymph
intracellular fluid
parts of the inner ear
-cochlea
-vestibular complex
-vestibulocochlear nerve (CN VIII)
length of inner ear
~ 1 cm across
function of cochlea
hearing
function of vestibular complex
balance
function of vestibulocochlear nerve (CN VIII)
-hearing & balance
-signals to brain
3 distinct regions of the bony labyrinth
-cochlea
-vestibule
-semicircular canals
parts of the vestibular complex
-vestibule
-semicircular canals
parts of the vestibule
-saccule
-utricle
-macula
function of vestibule
position of head
function of semicircular canals
rotational movements
parts of the semicircular canals
-semicircular ducts
-ampulla
structure in semicircular ducts
membranous labyrinth
structure in ampulla
hair cells
sensory receptors of the inner ear for both equilibrium and hearing
hair cells
what do hair cells continuously release?
release neurotransmitters to neurons
the apical surface of each hair cell has a covering of numerous long, stiff ______
microvilli (stereocilia)
long microvillus
kinocilium
effects of stereocilia and kinocilia bending
changes in the amount and rate of neurotransmitter release from the hair cell
shape of cochlea; feature
-snail-shaped spiral chamber
-hearing
what is the membranous labyrinth called?
cochlear duct
2 membranes of the cochlear duct
-vestibular membrane
-basilar membrane
2 categories of hair cells on the basilar membrane
-inner hair cells
-outer hair cells
these membranes partition the bony labyrinth of the cochlea into 2 smaller chambers on either side of the cochlear duct
-scala vestibuli
-scala tympani
location of the oval window
scala vestibuli
location of the round window
scala tympani
protected within the membranous cochlear duct
spiral organ
features of the spiral organ
-sensory epithelium
-hair cells and supporting cells
-tectorial membrane
gelatinous structure of the spiral organ
tectorial membrane
how are sound waves collected?
by the auricle of the external acoustic meatus
sound transmission in the middle ear
-amplifies sound waves
-stapes pushes on membranous labyrinth
-foot of stapes moves like a piston in the oval window
location where perilymph in bony labyrinth vibrates
scala vestibuli
what happens in the vestibular membrane relating sound transmission?
pushes on endolymph in membranous labyrinth
what happens in the tectorial membrane relating to sound transmission?
pushes on hair cells
changes in neurotransmitters during sound transmission due to what
impulse in spiral ganglion - cochlear branch of CN VIII
what is frequency?
the number of waves that move past a point during specific amount of time
2 types of frequency
-higher frequency
-lower frequency
location of higher frequency
stimulate basilar membrane closer to oval window
location of lower frequency
stimulate the spiral organ further away from the oval window
