Biopsych Exam 2 ch. 9 study

Amplitude is…

the percieved loudness of sound (decibels)

Frequency is…

pitch of sound (physical frequency of vibrations, Hertz)

What sensory system is hearing classified as?

Auditory system

pure tones are…

Tones with one frequency of vibration

• Oscillation between compression and expansion of air, creating the frequency

External ear does what? what structure does it contain?

• Captures, focuses, filters, and funnels sound into the ear

• ear canal: tube from pinna to middle ear

“Pinnae” also means…

Ears

Middle ear does what? What are it’s basic structures?

transfers vibrational energy + amplifies sounds

• tympanic membrane (ear drum): seals end of ear canal

• ossicles: chain of tiny bones that couple tmyp. membrane to inner ear at oval window (membrane under stapes)

→ smallest bones in the body: malleus (hammer), incus (anvil), stapes (stirrup)

• tensor tympani: attatched to malleus to tympanic membrane

• stapedius: attached to stapes

What is the eustachian tube?

A middle ear component to equalize the air pressure in both sides of the tympanic membrane

Inner ear does what? What are its basic structures?

Converts sound into neural activity

• cochlea: fluid-filled, coiled, snail-shaped structure

• 3 parallel ducts: scala vestibuli (vestibular duct), scala media (middle duct), scala tympani (tympanic duct)

• Organ of Corti: converts vibration (sound) into neural activity (in scala media)

• basilar membrane: separates scala tympani from scala media + vibrates in reponse to sound

• Inner hair cells (IHCs): transduce vibrations of basilar membrane into electrochemical signals (single row - 3,500)

• Outer hair cells (OHCs): “fine-tune” the cochlea to discriminate frequencies (3 rows - 12,000)

• stereocilia: stiff hairs on each hair cell

• tip links: fibers running along tips of stereocilia, generating APs

• round window: separates scala tympani from middle ear + vibrates opposite to vibrations in oval window

The mechanical opening of the sterecillium ion channels allows an inrush of ___ and ___ ions. This results in rapid ____ of the hair cell. This means there is a rapid influx of Ca2+ at the base of the ___.

K+ and Ca2+

depolarization

IHC

displacement of the basilar membrane peaks at..

cochlear base for high frequencies and the apex at low frequencies

auditory input from the nerves splits into 2 brances, 1 going to the…

ventral cochlear nucleus

1 path from each cochlear nucleus is bilaterally projected to the…

superior olivary nuclei

the “where” aspects of sound is in the dorsal stream of processing in the

parietal lobe

sequence of the auditory pathway

superior olivary nucleus → inferior colliculus → medial geniculate nucleus → primary auditory cortex

tonotropic organization:

arranged map of frequencies in order low to high in brain

inferior colliculi is the primary…

auditory center at midbrain, parallel paths converge here

Perilymph is like ___. Endolymph is ____ _.

CSF (high Na + Cl, low K)

High K