Senses: Senses Flashcards
A vibrating object pushes air molecules into zones of ___ separated by zones of ____.
compression; rarfaction.
waves per unit of time (cycles per second)
frequency; Hz. Higher freq = higher pitch
amplitude
measure of energy within the wave
loudness is
amplitude; intensity of sound energy = how much air molecules are compressed and rarified
The hearing range is
20 - 20,000 Hz (cycles/sec)
___ is the threshold of human hearing; log scale
0dB
___ is 10x threshold; log scale
10dB
___ is 100x threshold; log scale
20dB
___ is 1000x threshold; log scale
30dB
___ is threshold of pain
120dB
___ is threshold that can cause hearing damage.
> 90dB
Speech is usually at what freq.
around 1000hz (100-7000hz)
this structure funnels in sound
Auricle; aka: pinna
2 muscles that adjust vibrations of the eardrum:
the tensor tympani & the stampedius muscle
Vestibula & semicircular ducts have to do with:
equilibrium, movement of head, direction of gravity.
3 ear bones in order
bones are called ossicles. Malleus, incus, stapes.
passageways in the temporal bone:
the bony labyrinth
endolymph filled tubes floating in perilymph inside the bony labyrinth
the membranous labyrinth
perilymph is where?
btw the bony and membranous labyrinth. it surround the membranous labyrinth and basically acts as extracellular fluid.
perilymph and endolymph’s content?
perilymph is high in potassium and low in sodium. endolymph is high in potassium
endolymph’s location
the membranous labyrinth tubes.
3 tubes of cochlea
scala vestibuli
scala tympani
cochlear duct
which cochlea tubes connect?
scala vestibuli & scala tympani
Two distinct champers of the vestibule (name them) are involved in ___& ____.
Saccule & Utricle; headmovment & gravity
Extensive neural connection in ear is mostly:
sensory neurons but there is some motor output to the cochlea and to the muscles associated with the eardrum.
Name the semicircular ducts:
Anterior
Lateral
Posterior
Name the 3 tubes of the cochlea that are coiled together. What are in the tubes?
scala vestibuli: filled with paralymph (^K^Na)
scala tympani: filled with paralymph (^K^Na)
cochlear duct: filled with endolymph (^K)
which tube of the cochlea is connected to the oval window. Whats the other connected to?
scala vestibuli: connected to oval window
scala tympani: connected to round window
Spiral organ is also called:
organ of corti
receptor cells are called:
hair cells
3 rows of hair cells that don’t detect sounds are called ___ and have hair structures connected to the tips called:
outer hair cells; stereocilia
1 row of haris that detect sounds:
The inner hair cells, which also have stereocilia that are the sound detectors.
A pressure difference between __&__ causes the ____ to move. (????)
btw the cochlear duct and the scala tympani. causes the basilar membrane to move (???)
The receptor cells are resting on the ___.
Basilar membrane.
When we displace the basilar membrane, the ___ moves past the hair cells
tectorial membrane.
Basilar membrane causes sideway movement of the ____
tectorial membrane.
Outer hair cells are embedded in the___
The tectorial membrane.
There is motor output to which hair cells? and why?
the outer hair cells. The reduce how much the tectorial membrane moves back and fourth, and contributes to something called cochlear tuning, which decreases pitch discrimination.
Hair cells are found in our ___ and are found in both the __&___and ___.
inner ear and at the base of the semicircular canal where they give us equilibrium and balance. and also in the cochlea where they give us sound.
hair cells are connected at the tips by:
filaments called tip links.
tip links are connected to a
potassium channel, which is open and closed by the tip link.
why are hair cells staggered in height?
So that if you bend them one way, the potassium channel opens, then bend them the other way they close. Side to side = nothing at all.
If you get some things that are basically connected the same way and bend them one way they get further apart, bend them the other way the tips get closer together.
When the potassium enters the hair cells, is it stimulated or not stimulated?
stimulated.
A loud sound causes a bigger receptor potential and
it causes more potassium to enter the hair cell, causing more frequent action potentials.
motor output to the outer hair cells allows for better
pitch discrimination. its called cochlear tuning
what frequency causes the greatest displacement towards
the helicotrema region of the cochlea.
Louder sounds cause:
- frequency of AP’s (more vigorous vibrations causes higher frequency of AP’s)
- excites hair cells over a larger area because of greater displacement, stronger bending of hair cells.
- potential hearing damage because stereocilia cannot be replaced.
How do you get pitch discrimination?
where the displacements occur along the cochlea. which hairs are stimulated is from a specific pitch of sound.
How do loud sounds destroy your hearing?
Stereocilia do not grow back. So you can lose hearing at a specific frequency range. A big displacement along a certain part of the basilar membrane can shear off the stereocilia.
What kind of sound can cause more damage?
a faster developing sound has more potential to cause damage than a slow developing one because the 2 ear muscles don’t have time to clamp down on the ossicle bones to help prevent them from vibrating. (tensor tympani & stampedius msucle)
Vestibulocochlear nerve auditory pathway consists of:
Cochlear nucleus of the pons, supererior olivary nucleus of the pons, inferior colliculus of the midbrain, then projects on up to the thalamus, then (2 diff ways) 1. projects out here through our superior aspect of our temporal lobe where the primary auditory cortex is located and thats where you get the sensation of sound. 2. or to the auditory reflex area that coordinates reflex turning of the head (neck muscles).
Output can go from the superior olivary nucleus of the pons to:
the tensor typani and stapedius msucles that control the tympanic reflex, this reflex is activated every time you speak or else you’d deafen yourself.
Static equilibrium
when you’re not moving. sense of gravity. perception of head orientation
Dynamic equilibrium:
can be divided into linear acceleration - movement in a straight line. VS. angular accelaration - rotational moving.
Gravity is detected where?
in the Utricle and Saccule chambers of the vestibula. These can also detect linear accelaration to a certain extent.
Angular acceleration is found where?
in the semicircular duct.
How many different sets of orientations do we have?
3
Where are the receptors located in the semicircular duct.
in the swollen area at the base of each loop. called the ampullae.
What allows linear accelaration to be detected?
The weight of otoliths bends the stereocilia (static equilibrium). Heavy otoliths lag behind during linear acceleration. These are in the macula sacculi and macula utriculi.
the membrane within the macula’s is called:
a cupula.
What is a crista ampullaris?
Its the structure in the semicircular ducts that allows for equilibrium. the ampulla of each duct has a gelatinous cap (cupula) containing hair cells.
What allows head rotation to be detected?
The canal moves as the head turns. The endolymph lags behind due to inertia. The capula is pushed over and stimulates hair cells.
Vestibulocular reflex:
coordinates movements of your eye with movements of your head. So that as your moving and walking, your visual field isn’t bouncing
coordinates movements of your eye with movements of your head. So that as your moving and walking, your visual field isn’t bouncing
Vestibulocular reflex
Trace the vestibular projection pathways:
Vestibulocochlear nerve feeds into the vestibular nucleus at the pons. Goes to several places: 1. cerebellum - major coordination center. 2.midbrain where we have the superior colliculi (involved in unconscious movements of the eye). 3. Feeds into the thalamus which feeds up into our cortex (awareness of spatial orientation and movement)4.Feeds into reticular formation (involved in balance and posture).
