BIOD27H3 Lecture 13: BGYB30H3 Lecture 13 Notes Autonomic and Somatic Control-Oct 22
11 Aug 2010
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BGYB30H3 Lecture 13 Notes
-the pinna and ear canal direct sound into the ear
-sound waves hit the tympanic membrane (ear drum)
-malceus, incus, and stapes are bones in the middle ear that amplify the sound waves and
conduct them
-stapes connects to the oval window of the inner ear
-inner ear is filled with fluid and contains the cochlea, vestibular apparatus, and semicircular
canals
-cochlea is used in perception of sounds
-vestibular apparatus and semicircular canals are used for equilibrium
-the higher the pitch, the higher the frequency
-the larger the amplitude, the louder the sound
-sound wave first hits eardrum and turns into a vibration
-vibration travels through middle ear where it can be amplified
-vibration is converted into fluid waves at oval window
-fluid wave pushes on the tectoral membrane of cochlear duct where hair cells are found
-when hair cells are activated, neurotransmitter is released on sensory neurons
-action potentials are transmitted along cochlear nerve to the thalamus
-cochlea contains fluid called perilymph, which is similar to extracellular fluid
-cochlear duct contains endolymph fluid, which is similar to intracellular fluid
-cochlea contains vestibular, tympanic, and cochlear duct
-cochlear duct is found between the tectoral and basilar membrane
-organ of corti contains hair cells that bend when tectoral membrane bends
-fluid waves bend the hair cells
-fluid waves passing through vestibular duct create oscillations
-hair cells are non-neural receptor cells that contain stereocilia arranged in height
-kinocillium is the longest stereocilia and the tip links connect stereocilia
-movement of stereocilia generates signal transduction
-tonic signal is sent by sensory neuron at rest
-increased excitability causes more ion channels to open and an increased frequency of action
potentials in the cochlear nerve
-when hair cells bend in opposite direction, inhibition occurs
-high pitch sounds stimulate the thick part of the basilar membrane of the cochlear duct
-low pitch sounds stimulate the tail of the basilar membrane
-vestibular cochlear nerve (cranial nerve XIII) projects to the cochlear nuclei of the medulla
where it may crossover, then goes to the pons, thalamus, and finally the auditory cortex
-equilibrium requires sight, proprioceptors and inner ear
-dynamic and static components of equilibrium in the inner ear
-dynamic is the motion of the body and static is the body position relative to gravity
-saccule and utricle of the vestibular apparatus sense linear rotation and head position
-semicircular canals sense rotational acceleration in different directions
-Z}]Ì}vou}v]}Zµv]vPµZZl]vP}v[Z}]v]Ç]vPv}
-posterior monitors head moving from side to side like a cartwheel
www.notesolution.com
Document Summary
The pinna and ear canal direct sound into the ear. Sound waves hit the tympanic membrane (ear drum) Malceus, incus, and stapes are bones in the middle ear that amplify the sound waves and conduct them. Stapes connects to the oval window of the inner ear. Inner ear is filled with fluid and contains the cochlea, vestibular apparatus, and semicircular canals. Vestibular apparatus and semicircular canals are used for equilibrium. The higher the pitch, the higher the frequency. The larger the amplitude, the louder the sound. Sound wave first hits eardrum and turns into a vibration. Vibration travels through middle ear where it can be amplified. Vibration is converted into fluid waves at oval window. Fluid wave pushes on the tectoral membrane of cochlear duct where hair cells are found. When hair cells are activated, neurotransmitter is released on sensory neurons. Action potentials are transmitted along cochlear nerve to the thalamus.
