109522
Description
Flashcards by tanitia.dooley, updated more than 1 year ago
|
Created by tanitia.dooley
almost 11 years ago
|
|
| Question | Answer |
| What is the rinnes test for deafness? | tuning fork on mastoid process, when no longer heard then use sound conduction. If hear it- rinne +ve then ok, if not rinne -ve=conductive deafness |
| What is conductive deafness? How is it treated? | before cochlea- immobilisation of ossicles so cant act as lever, frequency dependent attenuation, can compensate with hearing aids, sometimes repond to antibioitcs and surgery |
| what is sensorineural deafness and what is it caused by? | cochlea- noise trauma, drugs, infections, congenital, presbycusis=all affect hair cells or auditory nerve tumour |
| What is the air presdure maintained by in the middle ear and why? | mastoid air cells, eustachian tube unequal pressures can distort the ear drum |
| What is the cochlea microphonic signal? | there are hair cells in the cochlea, diplacement of the hairs- sterocillia vend-receptor potential varies- net depolarisation- electrical potential of the perilymph at the round window |
| What are the characteristics of the cochlea microphonic signal? | no latency and no threshold |
| How does each hair display a sharp defined tuning curve? | each inner hair cell is tuned to respond to a specific frequency band- each afferent axon connects with only one hair cell |
| What is the webers test for deafness? | 1.Webers test- tuning fork in middle of scull (if hear through scull and not theough air= conductive deafness) If inner ear damage- heard on healthy side, if middle ear damage- heard on affected side |
| What are the two variables of travelling pressure waves? | 1. frequency 2.Amplitude |
| What is the normal range of frequency? | 20-20000Hz |
| How are pressure differences small? | less than 0.6% of atomospheric pressure |
| What is the sound attenuation reflex? | dampens down excessive loud sounds |
| Describe the sound attenuation reflex | two middle ear muscles (tensor tympani and stapedius) contract together- the handle of the malleus and the tympanic membrane are pulled inwards and the foot of the stapes is pulled away from the oval window= impede movement of tympanic mem and stapes at the oval window so less vibration passed to the cochlea |
| How much does the sound attenuation reflex reduce sound transmission by? | 20dB (~100 fold) |
| How long does the sound attenuation reflex last? | ~10minutes |
| What frequency of sounds does the sound attenuation reflex work for? What time scheme? | low over a long period of time |
| describe the transmission of waves in the middle ear | malleus is attached to the tympanic membrane- vibration of the membrane & so the malleus- the incus is attached to the malleus, incus is attached to the stapes and the foot of the stapes fits into the oval window |
| What happens to the pressure waves generated at the oval window? | they are propogated through the scala vestibule and to the round window where the energy dissipates |
| What is the role of the middle ear? | converts pressure waves in the air to vibrations of the perilymph in the inner ear |
| What does the inner ear control? | balance and hearing |
| Describe the auditory part of the inner ear | cochlea- bony canal 3.5cm long which spirals two and three quater turns around the modiolus (organ of corgi), has specialised hair cells, no axons-basilar regions covered with synaptic terminals of sensory neurone, embedded in tectoral membrane |
| What is the bony labyrinth? | the outer membrane of the inner ear |
| What is the role of the cochela, vestibule and semicircular canals? | cochlea- hearing/ vestibule and semicircular canals- balance |
| Describe how the vestibular canals are involved in balance? | 3D input of where abouts the head is- if move head, fluid in canal moves proportional to the movement of the head= distortion of hair cells=more channels open= hyperpolarisation & depolarisation=AP to cortices, provides info on orientation etc |
| Where is the middle ear? | from the tympanic membrane to the round and oval windows |
| Describe impendence matching | amplify the sound- greater area of tympanic membrane compared to the oval window and the lever action of the ossicles- have 3 bone orientation to increase the force of tympanic membrane when buckling |
| How much is the mechanical force of vibration amplidied from passage from tympanic membrane through ossicles to oval window? | ~20 fold |
Want to create your own Flashcards for free with GoConqr? Learn more.