CH9
CH9
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- what are the 3 kinds of taste papillae?
- fungiform (contains hundreds, only 1 tastebud, front), curcumvallate (back) and foliate (sides) (only have few,contain several tastebuds)
- where do the nerve fibres from vestib. receptors enter/synapse? some bypass and go where?
- lower levels of brainstem; synapse in vestibular nuclei; bypass and go to cerebellum
- how many auditory fibres make up the vestibulochochlear nerve?
- 30,000-50.000 on each side of head
- sensorineural deafness
- auditory nerve fibers unable to become excited in normal manner, hearing loss is usually permanent (Defects in hair structure)
- vomeronasal system
- detects pheromones
- central deafness
- hearing loss caused by brain lesions whihc can create word deafness (normal speach/hearing simple sound but cannot recognize speech)
- place theory
- argues pitch is encoded in the physical location of the activated receptors along length of basilar membrane. activation of receptors near base=treble sound, activiation near apex=base
- what is the outer hair cells job?
- fine tune organ of corti so that the IHC's can detect sound; OHC's can change their length which causes basilar membrane to stiffen/relax to sharpen tuning to diff. frequencies
- what is the minimum frequency humans can discriminate between?
- 2Hz
- volley theory
- proposes frequency of auditory stimuli is directly encoded in the firing pattern of auditory neurons (ex. 500 hz sound cause neurons to fire 500 AP/sec)
- what do the hills/valleys of the pinna do to sound?
- modifys the character of sound by amplifying or supressing; also important in sounds localization
- vestibulo-ocular relfex
- brainstem mechanism that maintains gaze on a visual object despite movements of head
- what moves the ossicles? what do the ossicles do?
- small displacements of tympanic membrane move ossicles; bones help concentrate timny mchenaical forces of vibrating air particles focusing pressures from large tymp. membrane onto small oval window
- the region of the cochlea nearest oval window is called what? other end?
- base;apex
- where do the receptors of the vestibular system lie? what does the vest. system consist of?
- within inner ear next to cochlea; consists of 3 semicircular canals oriented on different planes to detect angular acceleration
- coincidence detector
- divice that senses co-occurrance of two events (diff from both ears corresponds to place in space)
- what is special about smell compared to the other sense in relation to synapsing?
- smell can synapse directly to cortex without passing through thalamus
- olfactory epithelium
- a sheet of cells that lines the dorsal portion of nasal cavities and adjacent areas
- frequency
- number of cycles per second in sound wave (Hz), perception of this is pitch
- what are the two main streams of auditory processing in the cortex?
- dorsal stream (concerned with spatial location of sounds), ventral stream (analyze various components of sound)
- What type of sound is processed in the Heschl's gyrus?
- music
- what protudes from the ends up hair cells?
- tiny hairs called stereocilia (or just cilia) aranged by height
- what are the 3 canals that make up the cochlea?
- scala vestibuli (vestib. canal), scala media(middle canal), scala tympani (tympanic canal)
- what is located at the base of nerve cells? what are the 2 types?
- auditory nerve fibres; two are afferents that convey messagr from hair cells to brain; other two are efferents that convey messages from brain to hair cells
- what are the two parts of the superior olive that process intensity/latency?
- lateral superior olive=intensity, mdeial superior olive=latency
- what are the two theories that describe how we discriminate pitch?
- place theory, volley theory
- superior olive
- brainstem nucleus that is the primary sound localization nucleus in mammalian brain
- duplex theory
- sound localization involves processing both latency and intensity
- amplitude
- intensity, distance of curve above/below 0; our perception is loudness
- what is the pathway of sound after it enters the nerves?
- each auditory nerve fibre divides into 2 branches as enters brainstem, each branch goes to cochlear nuclei, one path of output of coch. nuc. is to superior olivary nuclei (first stage 2-ear effects processed), other paths go to inferior colliculi (primary aud. centres of midbrain), outputs of inf. collic. go to medial geniculate nuclei of thalamus
- tonotopic organization
- organizational feature in auditory systems where nuerons are arranged as orderly map of stimulus frequency which cells responsive to high freq. away from those responsive to low freq.
- papillae
- small projections from surface of tongue where taste receptor cells are
- taste buds
- each papilla holds one or more taste buds which hold cluster of taste receptor cells
- round window
- located on cochlea; moveable outlet membrane which allows fluid in cochlea to move
- what two muscles help protect ear from loud sounds by tensing?
- tensor tympani/stapedius (activated 80-90dB above threshold)
- where is the tympanic membrane (Eardrum) located?
- at end of ear canal and beginning of middle ear
- tip links
- threadlike fibres that run along tips of stereocilia and are key to AP's; when sound causes stereocilia to sway tension on tip links pop open ion channels
- what makes up the inner ear?
- cochlea/ vestibular apparatus
- auditory brainstem implants
- produce auditory sensations by directly stimulating cochlear nuclei of the brainstem bypassing ear alltogether
- what is at the base of the organ of corti? what does it seperate? what does it do?
- basilar membrane; separates scala tympani from scala media; vibrates in response to sound
- what 3 structures make up the organ of corti?
- hair cells, supporting cells, terminations of auditory fibres
- intensity differences
- differences in loudness at two ears; head shadow blocks equal loudndess from reaching both ears (headshadow most apparent with high frequency)
- what kind of energy are the stereocilia gated by?
- mechanical energy
- what is the difference between frequency and pitch?
- frequency is physical properties of sound, pitch is sensory experience of sound
- ototoxic
- toxic to the ear especially middle/inner ear
- gustatory system
- extends from taste receptors through brainstem nuclei and thalamus to cerebral cortex
- taste pore
- opening in the surface end of taste bud where cilia is extended into from receptor cells to contact tastants (substances that can be tasted)
- what makes up the middle ear?
- three bones call ossicles
- organ of corti
- converts sounds into neural activity
- what are the 3 semicircular canals of vest. system connected to? what does that do?
- utricle; responds to static positions of head (along with saccule which lies below utricle)
- high frequencies/low freq. cause what type of displacement in basilar membrane?
- maximal displacement near base where membrane is narrow; max. displacement near apex where membrane is wider
- what 2 types of hair cells are in organ of corti?
- inner hair cells (3500, flask shaped), outer hair cells (12000, cylindrical)
- what are the two types of binaural (two ear) cues to signal location of sound source?
- intensity differences, latency differences
- fourier analysis
- mathematical process that decomposes complex sounds into simple sine waves
- what does the inner ear do with sound?
- converts sound into neural activity
- what are the three types of cells in olfactory epithelium?
- receptor neurons, supporting cells, basal cells (all have dendrite that extends to outer layer of epithelium and cilia extends on mucous)
- ampulla
- englarged region of each semicicular canal that contains the receptor hair cells (in gelatinous mass) of vest. system
- what are the two ways frequency properties are actually coded in a sound?
- according to tonotopic representation (distrib. of excit. cells) and temporal patter of discharge in cells projecting to audit. cortex
- where is the oval window located?
- at end of middle ear, opening to inner ear
- latency differences
- diffrerences in time of arrival of sound to ears
- tinnitus
- senstaion of noises or ringing in the ears
- cochlea
- coiled, fluid filled structure in inner ear embedded in temporal bone of skull
- olfactory bulb
- projection of brain that provides receptors for smell
- vestibular system
- provides info about force of gravity on body and acceleration of head
- amusia
- disorder in which people cannot discern tunes
- what are the two kinds of latency differences?
- onset disparity (diff. hearing at beginnign of sound), ongoing phase disparity (continuous mismatch between two ears)
- otoliths
- small bony crystals on gelatinous membrane which increases sensitivity to movement
- conduction deafness
- arises when disorders of outer or middle ear prevent vibrations from reaching cochlea
- what are the five tastes that humans can detect?
- sweet (high calorie), savory/umami (protein), salty/sour (important aspects of homeostasis), bitter (toxins)
- pure tone
- tone with single frequency (sine wave)
- sensory conflict theory
- argues that we feel bad when we receive contradictory sensory messages especially when our vestib. and visual dont match
- what 3 bones make up the ossicles?
- malleus (hammer), incus (anvil), stapes (stirrup)
- what two things make up the external ear?
- pinna and ear canal that leads to eardrum