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35 Cards in this Set
- Front
- Back
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sounds waves compressed air vs. rarefied air graph: x-axis: one cycle, distance-->U shaped w/trough y axis= air pressure |
variations in air pressure, or the density of air molecules compressed air: peak, air molecules close together like at top of mountain rarefied air: air molecules are far apart (min. of air density |
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Pitch of sound, pitch vs. frequency |
*pitch is determined by frequency and is directly proportional to frequency *pitch is high or low *measured in cycles per seconds Hz *no matter how high frequency is, it moves around from source at speed of sound |
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Pitch of sound ultrasound vs. infrasound |
we perceive sounds btw 20-20k Hz ultrasound: higher than 20k Hz infrasound: lower than 20 Hz (low frequency) we can feel vibration but can't hear the frequency |
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intensity of sound |
difference in pressure btw compressed and rarefied patches of air *difference btw peak and trough on graph * determines loudness of sound *frequency can be the same but intensity can differ |
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The ear: external, middle, inner |
external & middle: air-filled spaces external: gather sound waves middle: amplify sound waves and transfers sound waves to--> inner ear: fluid-filled space that contain 2 sense organs-->detects mvmt/position of head in space 1.balance 2.hearing |
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The ear: external, middle, inner |
most sound waves bounce off when it contacts water due to higher resistance in water (can't hear as well under water when at a pool party) * need to increase force (amplify) in order to move the molecules of inner ear in response to the sound molecules
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The external ear:
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1. pinna (flappy bit for ear piercings) 2. external auditory canal (EAC) 3. tymphanic membrane--ear drum (TM) |
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External ear: pinna (auricle) |
gathers sound waves contributes to sound localization supported by elastic cartilage the lobule (lobe) lacks cartilage directs sound waves along EAC |
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External ear: (EAC) external auditory canal |
opens into petrous part of temporal bone wall of lateral 1/3 cartilage, medial 2/3 bony thin lining of skin contains glands like ceruminus and sebaceous which produce earwax (cerumen)
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external ear (TM tympanic membrane-- ear drum) |
dead end separates external ear from middle ear vibration of air causes vibration of TM (at same frequency) thin skin externally and mucous mem internally
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Middle ear |
tympanic cavity auditory tube (Eusachian or pharyngotympanic tube) connected to nasopharynx |
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Middle ear: tympanic cavity |
air-filled space within petrous temporal bone containing auditory ossicles connected to mastoid air cells by many variable channels (like nasal sinuses, spongy bone) recall: location of mastoid process and bone |
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middle ear: Auditory tube |
middle ear connected to nasopharynx via this tube and not to oropharynx thus this is the route in which middle ear is connected to outdoors *lined by mucus mem *walls are 1/3 bone, 2/3 cartilagenous latter closed at rest, but open with muscular contraction during yawning or swallowing equalizes P in middle ear w/ atmosphere prevents distortion of TM w/ changes in atmospheric p |
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middle ear: auditory tube Ear pops when there is change in atmospheric pressure (when TM can't equalize p when in elevator, in airplanes) TM is flexible |
normally: tube is closed, p equalized across TM but when going up CN tower in elevator pressure in EAC will drop while pressure in inner ear is still the same n since tube is closed, p cannot be balanced thus high p outside, low p inside so TM bulges outwards towards low p. To relieve this, you swallow so tube can open so that air can go in to equalize p thus TM is no longer distorted |
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Middle ear: auditory ossicles of tympanic cavity |
span tympanic cavity from TM to oval window oval window is btw air-filled middle ear and fluid-filled inner ear footplate of stapes sits in oval window & it is held in place by annular ligament so that fluid does not leak from inner ear into middle ear vibration of TM moves ossicles |
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Middle ear: auditory ossicles of tympanic cavity |
mvmt of ossicles increase force of sound waves which transmits them to oval window stapes moves like piston in oval window, initiating p waves in fluid of inner ear |
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Middle ear: modulation of footplate of stapes mvmt mvmt modulated by 2 SKM: tensor tympani and stapedius these 2 contract reflexively to loud sounds |
as sound waves hit TM there will be resistance due to contraction of these 2 SKM so vibration of TM will be decreased to lessen force transferred to inner ear hence can prevent damage caused by loud sounds but, sustained loud sound must happen first for this reflex to occur so damage might have already occurred |
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tensor tympani and stapedius paralysis of either muscle results in hyperacusis where sound is perceived louder than it is |
tensor tympani: decrease range of mvmt of TM (CN V:trigeminal)-->attaches to malleus and stiffens TM when it contracts hence more resistance stapedius: decreases mvmt of stapes in oval window (CN seven) |
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The Inner Ear I: consists of fluid-filled space, a bony labyrinth which houses a fluid-filled membraneous labyrinth |
-bony labyrinth is a convoluted space whose walls are compact bone but they have a membranes suspended within it -ex: tent made in living room, the walls are the bony labyrinth -when wind comes in (sound vibrations), it will sway the sheets (membranes) |
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The Inner Ear I:contains 2 sense organs |
-innervated by vestibulocochlear N (CN VIII) -vestibular apparatus and cochlea |
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The Inner Ear I: vestibular apparatus we use this to move in our environment -consists of vestibule (for linear acceleration sense and position) and semicircular canals (for angular acceleration sense) |
-senses equilibrium or the position & acceleration of the head in space- -can sense whether head is on side, down (static position in space) or if head is accelerated (when walking forward or backwards) or upwards when in an elevator or in rotation (cartwheel) -served by vestibular division of CN VIII |
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The Inner Ear I: cochlea |
-senses sound -2 nerves in 1, 1 at brainstem but two nerves when they arrive at sense organ which they are monitoring so cochlea is served by cochlear division of CN VIII |
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The Inner Ear II: bony and membraneous labyrinth |
know the table ML associated with each subdivision of BL |
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The Inner Ear II: bony labyrinth BL is surrounded by spongy bone with ML in it |
-interconnected spaces within petrous temporal bone: contains perilymph (CSF) -3 subdivisions: cochlea, vestibule and semicircular canals
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The Inner Ear II: membraneous labyrinth each portion of ML is responsible for different sensations ML is a sheet of cells and these cells are specialized to respond to waves |
-suspended within bony labyrinth: contains endolymph (~ICF)-->drains into CSF of skull -consists of cochlear duct, utricle & saccule and semicircular canals -utricle and saccule are both in vestibule |
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Table for Inner ear |
*cochlea (BL)-->cochlear duct (ML)--> hearing (sense) *vestibule (BL)-->utricle &saccule (ML)-->position, linear acceleration of head (sense) *semicircular canals (BL)-->semicircular ducts (ML)--> angular acceleration of head (sense) |
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The cochlea: -specialized for hearing -a coiled tubular space; walls made of compact bone (spiral staircase) |
-a subdivision of BL -spirals 21/2 times around the modiolus (peg of bone)--> the handrail of staircase -modiolus contains Ns and BVs -the cochlear duct (ML) is suspended within the cochlea; contained space is the scala media (space in the tent is scala media) |
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Cochlea |
-the cochlear duct spans the cochlea from the bony spiral lamina (SL) to the opposite wall -the cochlear duct subdivides the cochlear space into scala vestibule and scala tympani -the cochlear duct ends at the apex of the cochlea but scale vestibule and tympani are continuous at apex of the cochlea vis the helicotrema (all just one space) |
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Bony labyrinth: cochlea |
-subdivided into scala media, vestibule (above) and tympani (down below scala tympani) |
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Round window of cochlea |
-when stapes goes in at oval window, membrane covering over round window bulges out to maintain pressure inside the inner ear -when stapes pistons out of oval windows, membrane covering round window will go back in |
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Cochlea: vestibular membrane |
separates scale media from scala vestibule |
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Cochlea: basilar membrane |
-separates scala media from scale tympani -spiral organ (sense organ of hearing) is located on this BM |
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Oval window and round window |
-oval window/footplate of stapes are at the base of the scala vestibule -membrane-enclosed round window is at base of scala tympani |
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Movement in cochlea |
-like how the breeze moves the sheets in the room, membranes move in response to p waves -w/ vibration of the TM,the stapes moves in and out of the oval window like a piston -pressure waves initiated in the perilymph of the scala vestibule are relieved at the round window -the VM and BM vibrate in response to these p waves |
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The spiral organ |
-lies on the basilar membrane |
