Flashcards
Cochlea & Auditory system, and Vestibular system
Flashcards do conjunto (38)
- 1Human auditory system (diagram)
- 2Tympanic membrane (ear drum) and bones of ear
- 3EarsAll parts can be replaced
Ear canal is special shape
Ear drums is more efficient at the human voice range -> focuses the sound
Middle ear is usually air filled in healthy people
Fluid can be drained
Bones can be replaced - 4Inner earCochlea -> coiled tube
Vestibular system -> 3 semi-circular canals, for balance
All connected
All use sensory hair cells - 5Cochlea - development (diagram)
- 6Tonotopic MapFrequency sensitivity due to mechanism of basilar membrane, different portions of the membrane are maximally deformed by the sound of different frequencies.
When auditory axons in the auditory-vestibular nerve synapse in the cochlear nuclei, they do so in an organised pattern based on characteristic frequency. - 7Cochlear cross section (diagram)
- 8PerilymphFound in scala vestibuli and scala tympani
Ionic content similar to cerebrospinal fluid
Low K+ -> 7mM
High Na+ -> 140 mM - 9EndolymphFound in Scala media
Completely different to the other fluids
140 mmol K+
+80mV - 10Stria vascularisDifference in ion content of endolymph in scala media caused by active transport taking place in the stria vascularis
Reabsorbs Ca2+, secretes K+ - against their concentration gradients
Sets up endocochlear potential
Enhances auditory transduction - 11Hair cell (diagram)
- 12Hair cellTop is in endolymph, bottom is in perilymph
Sound is caused by the movement of the hairs going backwards and forwards (more laterally) - 13Ménière's diseaseAffects both auditory and vestibular system
Deafness, Tinnitus
Vertigo, Balance problems
Due to fluid imbalance
Other diseases due to the 'battery' loss
Less K+ in the endolymph - 14Organ of Corti (diagram)
- 15Organ of CortiSpecialised sensory epithelium
Direct mechanical stimulation (not like visual system)
Outer hair cells -> amplification
Inner hair cells -> 3,500 cells, primary - 16Organ of Corti - Movement of basilar membrane (diagram)
- 17Mechano-Electrical Transduction (Sensory)Actin filaments - make the stereocilia rigid rods that only bend at the base
Cross-link filaments link stereocilia so they move as a unit -> joint by tiplinks (cadherin)
Stereocilia - 3 micrometres in diameter - 18Stereocilia (diagram)
- 19Mechano-Electrical TransductionIt is the electrical gradient that is driving the positive ions in - not the concentration gradient
Depolarisation of the cell
Outward pump of K+ to restore/reset the membrane - 20Mechano-Electrical Transduction Hair cell (diagram)
- 21Electro-Mechanical Transduction (Amplification)Outer hair cell changes length based on membrane potential
Selectively processed
Allows hearing in newborns (through having no hair cells) to be treated -> Cochlear inplant - 22Innervation - outer and inner hair cells (diagram)
- 23Innervation - outer and inner hair cells3 outer hair cells for every inner hair cell
95% of the spiral ganglion neurones communicate with the inner hair cellls
IHC doesn't share spiral ganglion with other hair cells - wouldn't be able to tell the frequency
95% of the efferent neurones modulate our hair cells -> to protect the ears (temporary threshold shift) - 24Analysis of sound: Freuquency (pitch)Encoded in nerves by location along the basilar membrane
- 25Analysis of sound: Intensity (loudness)Encoded bin nerves by numbers responding and by firing rate
- 26Analysis of sound: Sound transductionInner hair cells
(and OHCs) - 27Analysis of sound: AmplificationOuter Hair Cells
- 28Auditory TractPrimary Auditory Cortex
^
Inferior Colliculus (IC)
^ Lateral Lemniscus
Superior Olivary Complex (S)
^
Cochlear Nuclei - AVCN, PVCN, DCN
^ Auditory Nerve
Sprial Ganglion - 29Cochlear NucleiAnterior ventral (AVCN), Posterior ventral (PVCN) and Dorsal (DCN) regions each have a tonotopic map
Individual cells have specific functions
eg. Primary responses in spherical & bushy cells (VCN)
Onset responses in octopus cells (CN)
Pauser responses in fusiform cells
AVCN contains relay cells to Medial Superior Olive - Calyx of Held, a giant fast synapse - 30Superior Olive (SO)Sound localisation
Medial SO - low frequency analysis, interaural time differences, received faithful inputs for calyx of Held on both sides
Lateral SO - high frequency analysis, interaural intensity differences - 31Inferior Colliculus (IC)Site of convergence of projections with complex frequency responses
Monoaural input from DCN - binaural from SO
Tonotopic maps
Responsible for attention reflexes, startle response, learned reflexes - 32CortexTonotopic map retained
Neurones with sensitivity to features in complex sounds
Auditory space maps,
Selective attention,
Inhibition of inappropriate motor responses,
Recognition of stimuli,
Discrimination of temporal patterns and short term auditory memory - 33Vestibular system
- 34Vestibular system5 different epithelia
Go via 8th nerve to the brain - 35Vestibular system cross section (diagram)
- 36Hair movement with head tilt (diagram)
- 37Vestibular system (diagram)
- 38Links between systems
Informações
- Descrição
- BSc Biomedical Science Year 1 FlashCards sobre Cochlea & Auditory system, and Vestibular system, criado por rachel-chads em 08-06-2014.
- Criado por
- rachel-chads
- Visualizações
- 81
- Avaliação