EAR Flashcards
In the inner ear we find…
Sensory organs for hearing and equilibrium
The source of sound causes movements of the … in its immediate neighbourhood; these movements cause disturbances in the air a little farther away from the source; these air particles in their turn affect their neighbours which are still farther away from the source; and so the disturbance spreads outward.”
air particles
Depending on the sound, one part of the cochlea or the other activates.
Sound reception and sound transmission is done by…
- The tympanic membrane
- The auditory or bony ossicles
- Oval Window
The bony ossicles:
- Modulate the movement of the …
- Apply force to the …– amplifying the incoming sound wave
- tympanic membrane
-oval window
The oval window transforms air pressure variations into…
Mechanical movements
A sound is any … of air that could cause a displacement of the … which, after transmission by the bone chain, could affect the … in the inner ear in such a way that the auditory … are stimulated.
disturbance, eardrum, liquid, nerves
What can we appreciate?
Scanning electron micrograph of the Organ of Corti. The hair- cell cell bodies are pseudo- colored blue
Hair cells in the cochlea can regenerate (T/F)
False: they cannot regenerate
Sterocilia are connected through one another with …
TIPS. They are important so as to help other sterocilia to bend, touching the tectorial membrane and amplifying the sound.
Hearing is initiated when … in air pressure are converted into fluid pressure that travel down the …
Variations in fluid pressure induce vibrations in the … that are transferred onto … cells
The … extends outward over the hair cells
When the basilar membrane and organ of Corti are displaced, … hit the tectorial membrane opening …. channels and depolarization of the hair cells occurs (opening Ca2+ channels). Then … occurs and K+ enters again.
oscillations, cochlear duct
basilar membrane, hair
tectorial membrane
sterocilia, potassium, repolarization
Action potentials in the VIII nerve keep a phase relationship with the sound stimuli,… for low frequencies and 1:n up to… KHz
1:1, 5
(100 vibrations/second=100 action potentials per second)
- IMPORTANT: Musicality is given by low frequencies
Type I cells connect with…
1 Inner cell
(THEY ARE THE MOST IMPORTANT ONES)
Type II cells connect with …
Several outer hair cells
General characteristics of the auditory pathway
- Tonotopic organization: frequencies will be represented at different points in the pathway.
- Multiple comissures: we have comissures in the brain connecting several nuclei, the pathway is very bilateral. Although we also have contralateral connections.
- Parallel processing: it is done in the brainstem and not in the ear. Frequency, time, location, intensity… all these characteristics are also processed in the brainstem (there is a subpathway for each type of info)
- Descending projections: help to reduce the input of some sources of info and to increase the input of others (centramos la atención en una conversación aunque haya otras personas hablando).
In the cochlear nuclei we find just one type of cell (T/F)
False: there are different types of cells. The same axon will connect with different cells and create parallel pathways.
… is common to any type of neuron
PERISTIMULUS HISTOGRAM
Tuning curve is measured for…
Soft sounds: if we increase the sound, we lose specificity.
- Frequency selective= small tuning curve
- Non-frequency selective= wide tuning curve
To measure how a neuron responds to a specific intensity we use the…
Rate-intensity curve
Superior olivary complex mainly … sound (function)
Also the … are responsible for the descending olivocochlear path (descending pathway)
Localises.
We can find: Medial olivary nucleus, Lateral olivary nucleus, Medial nucleus of the trapezoid body
Preolivary regions.
Which nucleus identifies?
Intensity differences between ears (level detector) Useful for high pitch sounds
Best developed in humans
Lateral superior olive and medial n. of the trapezoid body
Which nucleus identifies?
Phase (time) differences between ears (coincidence) Useful for low pitch sounds
Less developed in humans
Medial superior olive
With low pitch sound we can differentiate the …, and with high pitched the …
time, where it arrived first (right and left ear can be within the same cycle of the wave), intensities