Allison A&P Quizlet Import

what is the difference between anatomy and physiology?

anatomy is the study of structures of the body while physiology is looking at the functions of these body parts

what is the difference between the central and peripheral auditory system?

the peripheral auditory ststem is the outer, middle, and inner ear. the central auditory system is located in the brain

what are the three major anatomical planes? describe each

sagittal (longitudinal) separates right from left. transverse (axial) separates top and bottom. frontal (coronal) separates front from back

what are the two directions in which information travels ? ( terms for to and from the brain)

afferent arrives at the brain. efferent exits the brain

what bone houses the auditory system?

the temporal bone

what is the difference between longitudinal and transverse temporal bone fractures?

longitudinal fractures run along the axis of the temporal bone. they are more common and less severe. transverse fractures run perpendicular to the temporal bone. they are less frequent but more severe

which two cranial nerves are most important for audiologists to know about?

the 7th (facial) and 8th (vestibulocochlear)

what are the parts of the outer ear?

the pinna and external auditory meatus (ear canal)

what is the outer ear made of?

ligaments and cartilage covered by skin

which frequencies are best amplified by the pinna?

high frequency sounds (5,000 Hz)

why is the pinna best at amplifying high frequency sounds?

the wavelengths of high frequency sounds are smaller and are harder to pass around the pinna

which frequencies does the ear canal amplify best?

3000-4000Hz

what is the purpose of the outer ear?

collect and funnel sound to the tympanic membrane

what is the main function of the middle ear? how does it carry out this function?

the ear's main function is to increase acoustic energy to address the impedance mismatch. it does this through the area differential (between the TM and oval window), lever action of the ossicular chain, and the buckling of the curved tympanic membrane

where is the bony cochlea located?

it is embedded in the petrous portion of the temporal bone

describe the shape of the cochlea

snail shell shaped with 2.5 turns

what is the modiolus?

the bony core running through the cochlea that carries blood and nutrients to the cochlea

what is the habenula perforata?

the small holes that nereve fibers exit the organ of corti through

what is the spiral lamina?

the shelf like structure that winds around the moduolus. it provides the support for the organ of corti

what are the three major parts of the cochlea?

the semicircular canals, vestibule,and cochlea

what is the membraneous cochlea?

a membrane housed within the bony cochlea. surrounded by fluid and contains fluid

what are the two fluids of the inner ear? describe them and where they can be found

perilymph - high in sodium, low in potassium, in the scala vestibuli and scala tympani, neurally charged. endolymph - high in potassium, low in sodium, positively charged, in the scala media

what is the helicotrema?

where the scala vestibuli and scala tympani meet

what is tonotopic organization?

describes how a system is spacially organized by frequency

what is the purpose of auditory nerves?

carries electrical impulses from the cochlea to the brainstem

what is the difference between type 1 and type 2 auditory nerve cells?

type 1 - unmyelinated and then myelinated, longer, more of them, attatch to inner hair cells, high concentration to each cell. type 2 - unmyelinated all the way through, shorter, less, one nerve attatches to many outer hair cells

what is the order of the central auditory system ?

cochlear nucleus, superior olivary complex, lateral lemniscus, inferior colliculus, medial geniculate body, auditory subcortex, auditory cortex, inhermispheric pathways

what is the typical length of the adult ear canal ?

2.5-3 cm long

what is the purpose of cerumen?

keep foregin objects out (dust and bugs), antibacterial, antifungal, moisturizes the ear

what are the two glands that make cerumen?

sebaceous and ceruminous

describe the physical makeup of the ear canal

outer 1/3 is cartilage. inner 2/3 is bone.

what is the ithmus?

the point between the two turns/bends of the ear canal. it is the skinniest point of the canal

what is atresia? what is microtia?

microtia is a small outer ear. atresia is no ear canal

what is the head shadow effect? what are the two localization cues we get from it?

the idea that the presence of the head prevents signals from reaching both ears at the same time. interaural intensity (high freq) difference and interaural time (low freq) difference are the two cues that follows

what are the two major parts of the middle ear?

epitympanum (top part) and the tympanic cavity

explain the box model of the middle ear

lateral side : tympanic membrane ; medial side - cochlea; superior side : tegmen tympani; inferior boundary: tympanic plate/ jugular wall; anterior boundary: carotid wall; posterior boundary : mastoid wall

what are the three layers of the tympanic membrane made of? where do all three layers connect?

epidemal lining, fibrous material (radial and concentric), membranous. they all connect at the annulus

what are the two major parts of the tympanic membrane?

the pars flaccida (the top part) and the pars tensa (the large and tight part)

what is tympanosclerosis?

thickening/scarring on the tympanic membrane

what are the three bones of the middle ear? what are the ywo muscles of the middle ear?

malleus, incus, stapes are the bones. the tensor tympani and stapedius are the muscles

what is the eustachian tube made of?

the lateral 1/3 is bony. the medial 2/3 is cartilagenous

what is the purpose of the eustachian tube?

supply the middle ear with fresh air, equalize pressure on either side of the tympanic membrane, drain any fluids in the middle ear space

what are the two muscles responsible for opening and closing the eustachian tube?

tensor veli palatini and the levator veli palatini

what are resistance factors? what are the two major ones in the ear?

resistance factor is the loss of energy caused by friction. the two major resistance factors in the ear are mass and stiffness

what is otosclerosis?

bony growths on the stapes footplate. most common in middle age women, specifically those who are pregnant. solved with a stapendectomy (insertion of a prosthetic stapes) or a ossicle repositioning.

where does blood and nutrients enter the cranium?

the foramen magnum

what is the most dense bone in the body?

the petrous portion of the middle ear

what are the four quadrents of the internal auditory meatus ?

7up and coke down (always no matter what side it is on), V8 in the back

what is the internal auditory canal?

a bony passage in the temporal bone that connects the inner ear to the brain

what are the two fluid pathways of the inner ear?

the vestibular aqueduct (brings endolymph) and the cochlear aqueduct (brings perilymph)

describe tonotopic organization of the basilar membrane

the base is narrow and stiff to accomodate high frequencies while the apex is wide and floppy to accomodate low frequencies

what are the two cell layers of Reissner's membrane? what is in the middle?

on the endolymph side = epithelial. on the perilymph side = mesothelial. in the middle = basement membrane

what is the reticular lamina?

the ceiling of the hair cells of the organ of corti. keeps the endolymph and cortilymph separate

what is the stria vascularis?

responsible for the secretion and absorbtion of endolymph. rich in blood vessels. helps to establish the endocochlear potential

what are the differences between inner and outer hair cells?

outer hair cells - w shaped, -60mV charge, embedded in the tectorial membrane, 3 -5 rows, cochlear amplifiers. inner hair cells - u shaped, -40 mV charge, NOT attatched to the tecorial membrane, 1 row, sensory cells

what are tip links? what is the difference between cross links?

tip links are the gates to ion channels. when they are open, potassium ions are able to flow into the cells. crosslinks allow the hair cells to move all together

describe depolarization and hyperpolarization of hair cells

depolarization allow for the charge within the cell to be similar to the charge surrounding the cell. polarization means that the outside of the cell is more positive. depolarization is upward movement of the basilar membrane (rarefraction), clockwise rotation of the streocillia, opening of the tip links, influx of potassium, and hair cell excitation. hyperpolarization is the opposite. there is downward movement of the basilar membrane (condensation), counterclockwise rotation of the stereocillia, closing of the tip links, reduced flow of potassium, inhibition of the hair cells

what is the tallest/leader hair cell called?

the kinocillium

what is the traveling wave theory?

the idea that all sound waves enter the cochlea at the base and travel along the basilar membrane until the characteristic frequency is met

what does compression and rarefraction look like in the cochlea?

a compression wave has the stapes window pushed in and the round window pushed out. the basilar membbrane is pushed downards. in a rarefraction wave, the basilar membrane is pushed upwards as the round window is pressed in and the stapes buldges out

does the basilar membrane move faster at the apex or the base?

the apex since the stiffness gradient decreases

how does the basilar membrane encode loud sounds?

basilar membrane displacement and the amount of hair cells stimulated

why is are the outer hair cells known as cochlear amplifiers?

the outer hair ells contract and expand upon their downward deflection. this boosts the amplitude of the traveling wave and therefore leads to the fine tuning of the characteristic frequencies across the basilar membrane. this feature only works for mid-intensity sounds

what is the upward spread of masking?

a loud low frequency sound stimulates the high frequency section of the basilar membrane. any additional high frequency sounds cannot be encoded as that section of the basilar membrane has already been stimulated.

what is hansen's stripe?

part of the tectorial membrane that prevents the inner hair cells from being embedded in the tectorial membrane

what is the role of inner hair cells in terms of hair cell mechanics?

releases neruotransmitters to generate action potentials

what is the role of outer hair cells in terms of hair cell mechanics?

they are the cochlear amplifiers (responsible for the contraction and expansion)

what is the inner hair cell's responsibility in transduction?

they are the sensory cells

what is the outer hair cell's responsibility in transduction?

they are the modulators of transduction

what is depolarization? what is the difference between polarization?

depolarization causes the charge inside and outside a cell to be the same. it raises the change inside the cell. polarization creates a difference in charge inside and outside of the cell. it makes the outside of the cell more positive

what does depolarization of the outer hair cell look like?

contraction of the cell body and increased movement of the basilar membrane

what does depolarization of the inner hair cell look like?

release of neurotransmitters (like glutamate) and excitation of auditory nerve fibers

overall, what does depolarization look like in the cochlea?

rarefraction wave. basilar membrane moves up. stereocillia are sheared. tip links open. potassium enters the hair cell. excitation occurs due to hair cell firing

overall, what does hyperpolarization look like in the cochlea?

compression wave. basilar membrane moves down. sterocillia rotate counterclockwise. tip links close. no potassium. inhibition of hair cells

what is prestin?

a protein that 1) detects changes in transmembrane voltage (voltage sensor) and 2) undergoes a change that leads to the electromotile response (artuator molecule)

what is glutamate?

the afferent excitatory transmitter released by the inner hair cells

what is acetylcholine (Ach)?

the efferent inhibatory neurotransmitter

besides glutamate and acetylcholine, what are other neurotransmitters in the inner ear?

dopamine, GABA, substance P, enkephalins, dynorphins

explain otoacoustic emissions

measuring the sounds generated by the inner ear by outer hair cells that propgate back into the external ear canal. it is measured with a probe that has a speaker and microphone

what are the four cochlear potentials of the inner ear?

endocochlear potential, cochlear microphonic, summating potential, compound action potential

what is the endocochlear potential?

the positive voltage ( ~ 80-100 mV) that occurs in the cochlea's endolymphatic spaces

what is the cochlear microphonic?

represents the summation of the individual responses from a large number of hair cells (predominately outer hair cells) along the basilar membrane. the alternating current (AC) frequency response mimics the stimulus

what is the summating potential?

follows the envelope of the stimulus. inner and outer hair cells contribute. the polarity is negative at the characteristic frequency but reverses polarity in repsonse to lower or higher frequencies

what is the compound action potential?

the sum of the synchronous responses of auditory nerve fibers in the spiral ganglion

what are the two prominant negative peaks of the compound action potential?

N1 = ~ 1 ms ; N2 = ~ 2 ms

what is the lowest stimulus level of the compound action potential?

~10-20 dB above behavioral threshold

what is electrocochleography (ECoG)?

a way to record the cochlear microphonic, summating potential, and action potential at the same time. uses an electrode and click stimuli

what are the three different types of OAEs?

spontaneous, transient evoked, distortion product

what are spontaneous OAEs?

OAEs that occur in the absence of stimulation

what are transient evoked OAEs?

measuring the sounds produced by the inner ear in response to clicks or tone bursts. uses averaging since responses are small. typically used in newborn hearing screenings

what are distortion product OAEs?

two pure tones are played. a new pure tone is sent back (2f1-f2). graphed on a DP-gram

what is the main function of the auditory nerve?

transmits information about sound intensity, frequency, and time to the brainstem (after initial processing by the cochlea)

what cranial nerve is the auditory nerve a part of?

8th cranial nerve

what two parts of the body does the auditory nerve connect? what is its pathway?

the cochlea to the brainstem. hair cells, habenula perforata, modiolus, internal auditory meatus, cerebellopontine angle (CPA), brainstem at the posterior pontomedullary junction

how long is the auditory nerve?

22-26 mm

what are the differences between type 1 and type 2 nerve fibers?

type 1 - 90-95%, high concentration to inner hair cells, transmit sounds, longer, more myelin. type 2 - 5-10%, little myelin, supporting nerves

explain the tonotopic organization of the auditory nerve

nerve fibers are arranged based on frequencies they transmit. high frequency at the outside. low frequency in the middle

explain the four quadrens of the internal auditory meatus

v8 in the back (vestib portion of the 8th nerve), 7up (facial nerve), coke down (cochlear and auditory)

what are common symptomsof auditory nerve tumors?

tinnitus, poor WRS, absent acoustic reflex, usually unilateral (unless they have NF2)

what is auditory neruopathy spectrum disorder?

the ear properly detects sound but has a hard time transmitting the sound to the brain for processing