Week 7. Other Senses Flashcards
What are the 3 properties of audition?
1) Pitch (frequency)
2) Loudness (amplitude)
3) Timbre
What is frequency?
Refers to the number of cycles per second
Higher frequency -> more cycles per second
Related to pitch
high freq -> high pitch
low freq -> low pitch
What is amplitude?
Refers to magnitude of wave as measured from peak to trough.
Related to loudness.
What is timbre?
Tone colour/quality
relates to other secondary frequencies present in the signal. identical air vibrations means same timbre.
What is the pinna and where is it located?
A structure that alters the reflection of sound waves, and helps us locate source of sounds in the vertical axis.
Found in outer ear.
What is the tympanic membrane (eardrum)?
A membrane that connects the outer and middle ear
Vibrates when struck by sound waves
Moves the 3 tiny bones of the middle ear
What are the names of the 3 tiny bones of the middle ear?
Malleus, Incus, Stapes.
What is the middle ear filled with and what is found there?
Air-filled
3 tiny bones found there
What is the oval window?
Connects the middle and inner ear
What is the eustachian tube?
connects middle ear with mouth cavity
What is located in the inner ear?
auditory receptors
Which structure contains auditory receptors and mediates audition?
Cochlea (snail-shaped structure)
What do the 3 semicircular canals do?
Mediate balance
There are 3 chambers in the cochlea. What are they filled with and what are their names?
Fluid-filled chambers. Fluid is called endolymph, which vibrates when the oval window vibrates.
Scala vestibuli, scala media, scala tympani.
Which structure is found in the middle chamber of the cochlea?
Organ of corti
What is the importance of the outer ear?
Reflects sound waves, important for sound localisation
What is the importance of the middle ear?
Amplifies sound waves through 3 tiny bones
What is the importance of the inner ear?
Contains cochlea that mediates audition and semicircular canals that mediate balance.
The organ of corti is composed of 3 structures, what are they?
1) tectorial membrane (top)
2) Hair cells (sensory neurons)
3) Basilar membraine (bottom)
The cilia of haircells in the organ or corti are joined together by molecular chains called ____.
tiplinks
What is mechanotransduction? Where does it occur?
Refers to the conversion of mechanical energy (movement) into electrochemical energy (cell polarisation). Occurs in hair cells.
Describe the general idea of mechanotransduction.
Air vibrations converted into vibrations of tympanic membrane, which in turn moves the 3 tiny bones, which moves the oval window membrane of cochlea. This generates action potentials in auditory nerve.
How do movement of the hair cells generate the auditory nerve?
they excite ganglion cells
What happens to the liquid in the chamber of the cochlea when the oval window membrane vibrates?
Movement of liquid in the chamber moves the membrane up and down at the same frequency as the sound frequency, and with an amplitude proportional to sound amplitude.
The organ of corti moves up when there is a ______ and moves down when there is a _____.
Depolarisation; repolarisation
What happens to the cilia when there is a movement of the organ of corti during a depolarisation?
The upward movement generates a deflection of the cilia towards the left because the tectorial membrane is laying on top of them.
The endolymph in the middle chamber is very ____ in K+ at the apex. The base of the haircell is ___ in K+.
High; low.
What condition results from the damage of delicate hair cells? What treatment can be used?
deafness. cochlea implants can be used to restore audition. array of electrodes is slowly pushed through the chambers to electrically stimulate different sections of the cochlea.
What condition results from the damage of delicate hair cells? What treatment can be used?
deafness. cochlear implants can be used to restore audition. array of electrodes is slowly pushed through the chambers to electrically stimulate different sections of the cochlea. It converts sound waves into patterns of electrical stimulation.