The ears The structure of an ear Outer

• • • The ears The structure of an ear Outer ear Middle ear Inner ear The hearing process

The ears • • • one of the 5 sense organs detect sound provide the sense of hearing help to detect the movement of the body help to keep the balance of the body by detecting the position of the head

The structure of an ear • Divided into 3 parts: outer ear middle ear inner ear

Outer ear • Consists of 3 structures: ear pinna • collects and directs sound waves ear canal • directs sound waves to eardrum • vibrates when hit by sound waves

Middle ear • Consists of 4 structures: ear bones • 3 ear bones • amplify sound vibrations • pass on vibrations to oval window

Middle ear • Consists of 4 structures: ear bones oval window • transmits sound vibrations to inner ear

Middle ear • Consists of 4 structures: ear bones oval window round window • releases pressure from sound waves

Middle ear • Consists of 4 structures: ear bones oval window round window Eustachian tube • equalizes pressure on both sides of eardrum

Inner ear • Consists of 2 structures: semicircular canals • contain sensory hair cells • detect the directions of head movement

Inner ear • Consists of 2 structures: semicircular canals cochlea • contains sensory hair cells which • detect pressure changes and produce nerve impulses

The hearing process 1 The ear pinna collects sound waves. Sound waves pass along the ear canal.

The hearing process 2 Sound wave makes the eardrum vibrate.

The hearing process 3 Ear bones move to amplify and transmit the vibrations to the oval windows.

The hearing process 4 Oval window vibrates and 5 makes the perilymph in the cochlea vibrate.

The hearing process 6 Perilymph transmits vibration to endolymph.

The hearing process 7 Sensory hair cells in endolymph are stimulated and send off nerve impulse.

The hearing process 8 Auditory nerve transmits nerve impulses to the brain.

The hearing process 9 Auditory centre interprets the nerve impulses.

The hearing process 10 Pressure built up in perilymph is released at the round window.

Summary The structure of an ear bones ear pinna semicircular canals ear canal eardrum oval window round window cochlea Eustachian tube

The hearing process Collection of sound waves transmission of sound waves amplification of sound waves + vibration of body liquid detection of vibration transmission of nerve impulses interpretation of nerve impulses sensation of hearing