Auditory Flashcards
What does the external ear consist of?
The auricle (collects sound), external acoustic meatus (ear canal) and the tympanic membrane (ear drum).
What are the 3 bones in the middle ear?
Malleus, incus and stapes
What 2 muscles are in the middle ear that limit loud noises?
Tensor tympani and stapedius
What are the two major divisions in the internal ear?
The bony labyrinth filled with perilymph and th membrainous labyrinth containing endolymph.
What is the vestibule?
Central egg-shaped cavity of the bony labyrinth. Houses equilibrium receptor regions which report changes in head position.
What are the semicircular canals?
Made up of anterior, posterior and laterial canals, detect rotational movements of the head via the ampulla.
What is tehe cochlea?
A spiral bone chamber which houses the receptor organ for earing (spiral organ or organ of corti)
Summarize human hearing by steps.
Vibrations in the ear beat against eardrum, pushes a chain of tiny bones, press fluid in the internal ear, set of shearing forces that pull on tiny heir cells, stimulate nearby neurons, give rise to APs, travel to brain to interpret.
What is step 1 in the pathway of sound waves?
Tympanic membrane (vibrates ear drum)
What is step 2 in the pathway of sound waves?
Auditory ossicles (bones propagate vibrations to oval window)
What is step 3 in the pathway of sound waves?
Scala vestibuli (perliymph in the scala vestibuli vibrates)
Wha is step 4a in the pathway of sound waves?
Helicotrema path (low frequency sounds go through the cochlea and back, too low to activate the spiral organ)
What is step 4b in the pathway of sound waves?
Basilar membrane path (high frequencies vibrate hair cells creating action potentials sent to the brain)
How are vibrations turned into action potentials?
The hairs are connected to gated ion channels. When they vibrate, channels open and let ions through creating electrical potential.
What is the purpose of the outer hair cells?
Increases reponsiveness of the inner hair cells by aplifying motion, and helps protect the inner hair cells from loud noises.
