Bio 449 Lecture 11 - Sensory Physiology III Sep. 20, 2010

Somatosensory system (conclusion)Equilibrium

Audition - the earStructureFunction

Terms to Know

Hair cellStereociliaKinocilium

Otoliths (statoconia) Otolith organs (maculae)

Semicircular canalAmpullaCupula

Tympanic membraneAuditory ossiclesCochleaOval windowRound windowOrgan of CortiBasilar membraneTectorial membrane

ReadingsLectures 10-12: Chapter 10, pages 349-379Lectures 13-14: Chapters 6 & 7

Hair Cells

–30

0

Membrane potentialof hair cell

Action potentials inprimary sensory neuron

Excitation opension channels

Inhibition closesion channels

Release Release

mV

(a) At rest (b) Excitation (c) Inhibition

Tip link

Stereocilium

Hair cell

Primarysensoryneuron

More channelsopen.Cation entrydepolarizescell.

Channels closed.Less cation entryhyperpolarizes cell.

Action potentials Action potentials increase No action potentials

Somechannelsopen

Time

mV

Fig. 10-22

Hair Cells

Anatomy of the Ear

Fig. 10-18

MIDDLE EAR INNER EAREXTERNAL EAR

NervesSemicircular

canals

Vestibularappartus

Cochlea

Cochlea

Saccule

Utricle

Maculae

SEMICIRCULAR CANALS

Superior

Horizontal

Posterior

OTOLITH ORGANS

Cristae withinampulla

Vestibular Apparatus

Fig. 10-25

Otolith organs

Kinocilium Stereocilia

Sensorynerve fibers

Supportingcells

Hair cells

Gelatinouslayer

Otoliths

Similar toFig. 10-25

Otolith Movement

Cochlea

Saccule

Utricle

Maculae

SEMICIRCULAR CANALS

Superior

Horizontal

Posterior

OTOLITH ORGANS

Cristae withinampulla

Vestibular Apparatus

Fig. 10-25

Orientation of Semicircular Canals

Vestibularapparatus

Superior canal(nod for “yes”)

Horizontal canal(shake head

for “no”)

Posterior canal(head tilt)

Left right

Endolymph Movement

Direction of rotation of the head

Endolymph

Bone

Bone

Cupula

Hair cells

Anatomy of the Ear

Fig. 10-18

MIDDLE EAR INNER EAREXTERNAL EARThe pinna

directs soundwaves into

the ear Ovalwindow Nerves

Topharynx

Eustachiantube

Tympanicmembrane

Roundwindow

Stapes

IncusMalleus

Earcanal

Cochlea

Anatomy of the Inner Ear

Cochlea

Helicotrema

Basilarmembrane

Tympanicduct

Roundwindow

Cochlearduct

Organ ofCorti

Uncoiled

SacculeOval

windowVestibular

duct

Anatomy of the Inner Ear

Basilarmembrane

Tympanicduct

Cochlear nerve transmitsaction potentials fromthe hair cells to theauditory cortex.

Tectorial membrane

Cochlear duct

Vestibular duct

Organ of Corti

Bony cochlear wall

Transmission of Sound

5

6 4

3

2

1

Ear canal Malleus

Incus

Stapes

Cochlear nerve

Vestibular duct(perilymph)

Roundwindow

Tympanicmembrane

Cochlear duct(endolymph)

Tympanic duct(perilymph)

Ovalwindow

Transmission of Sound

Tectorialmembrane

Nerve fibers ofcochlear nerveBasilar membrane

Haircell

Cochlearduct

Tympanicduct

The movement of the tectorialmembrane moves the cilia onthe hair cells.

Fluid wave