Hearing and Equilibrium Flashcards
Sound transduction
- This occurs after the trapped stereo cilia of the hair cells are deflected by the basilar membrane movements
- Moving the hair cells affect the tip links
Outer hair cells
- They’re efferent
- They receive signals from the brain and alter the tension of the tectorial membrane to improve hearing sensibility by amplifying quiet vibrations
- Help you to distinguish between very similar sound frequencies
Inner hair cells
- They’re sensory.
- They send signals along the cochlear branch of the vestibulocochlear nerve
- Senses equilibrium
Auditory processing
Pitch (frequency): Perceived by hair cells in different positions along the basilar membrane
- Loudness (volume): Perceived by greater amplitude vibration in the fluids of the cochlea = larger deflections of hair cells = larger grade potentials = more frequent action potentials
Vestibule
Central cavity of the bony labyrinth
Contained two membranous sacs that house maculae
Maculae
- Equilibrium receptor regions.
- Monitors the position of the head in space.
- Responds to linear acceleration (elevators movements)
Semicircular canals
- Project from the posterior aspect of the vestibule
- Contains a semicircular duct that has an ampulla
Ampulla
A nodular (lump) on one end of the semicircular ducts that contains an equilibrium receptor, the crista ampullaris
- Crista ampullaris: detects angular/rotational acceleration
Utricle
- Near the semicircle canals
- The maculae of the utricle are horizontal with vertical hairs
- Forward/backward movements stimulate the utricle
Saccule
- Near the cochlea
- The maculae of the saccule are vertical with horizontal hairs
- Up/down movements stimulate the saccule
Equilibruim
Hair cells release neurotransmitter continuously, but acceleration/deceleration causes a change in the number of neurotransmitters released, which leads to a change in action potential frequency
Cristae ampullares
- Located in the ampulla of the semicircular canals
- Detect rotational acceleration
