The EarThe ear is the sensory organ that allows us to

hear. It converts airborne sounds waves into nerve

impulses that are decoded by the brain

Parts of the earOuter ear (external)• Auricle or Pinna

- This is the visible part of the ear.

2) The auditory canal

- It gathers sound waves from the environment and directs them along the auditory canal

– is 3.75 cm long– Has walls lined with hairs and glands that secrete

wax these prevent foreign particles from entering the ear

– Ends at the tympanic membrane or eardrum

2) The middle ear• The eardrum or tympanic membrane• Three small bones or ossicles (maleus -

hammer, incus- anvil, stapes- stirrup)• It is linked to the Eustacian tube which

serves to equalize the air pressure on the two sides of the eardrum

3) The inner ear• a fluid filled cavity in the temporal bone• Contains the semicircular canals and the

cochlea

For your information

The takeoff or landing of an airplane, the acceleration of an elevator, deep-sea diving, or driving up a steep hill in a car all bring about changes in air pressure which may be experienced as discomfort in the ears. This feeling is the result of increased pressure being exerted on the eardrum, which causes it to bulge on one side or the other, depending where the pressure is higher. Usually the act of yawning, swallowing, or sneezing opens the Eustachian tube, equalizing the pressure on the two sides of the eardrum and relaxing this membrane.

Cochlea• spiral-shaped• fluid-filled inner ear structure• lined with cilia (tiny hairs) that move when

vibrated and cause a nerve impulse to form • The axons of cilia form the auditory nerve that

sends auditory signals to the brain

• Ear• Cochlea• Auditory

Nerve• Brain

• Transformer• Analyzer• Conductor• Receiver

Match the following words with the correct term

• Ear• Cochlea• Auditory

Nerve• Brain

• Transformer• Analyzer• Conductor• Receiver

Ear Receiver

Conductor Auditory Nerve

Cochlea Transformer

Brain Analyzer

Hearing & the earThis is the chain reaction which takes place in the hearing process:(put the following words in the appropriate order)

sounds waveshearingVibration of the eardrumauditory canalcenter for hearing in the brainthe auriclethree bones of the middle earnerve impulse is triggered in the auditory nervecilia move (inside cochlea)

Chain Reaction of Hearing

sound waves the auricle the auditory canal vibrations the eardrum the three bones of the middle ear cilia move (inside cochlea) nerve impulse is triggered in the auditory nerve the center for hearing in the brain hearing

Hearing loss and prevention

• 3 Main causes of hearing loss:

1. Partial or total blocking of the auditory canal by wax

Hearing loss & prevention

• 3 Main causes of hearing loss:2. Rupture of the eardrum

Ear Drum or Tympanic membrane

Hearing loss & prevention

• 3 Main causes of hearing loss:

1. Ear wax

2. Rupture of the eardrum

3. Loss of sensitivity of the

mechanical structures (eardrum, small bones of the middle ear)

Otitis

• Inflammation and/or infection of the middle ear• Acute otitis media (acute ear infection) occurs

when there is bacterial or viral infection of the fluid of the middle ear, which causes production of fluid or pus.

• Chronic otitis media occurs when the eustachian tube becomes blocked repeatedly due to allergies, multiple infections, ear trauma, or swelling of the adenoids.

Review Questions

1) What part of the ear gathers sound waves in the air?2) What name is given to the structure that connects the

ear to the nose?3) How does the ear protect itself from unwanted

incoming particles?4) What two structures compose the inner ear?5) What structure contains the hearing receptor cells?6) Which part of the ear houses the nerve endings for

hearing?7) When does a person experience the sensation of

hearing?

1) What part of the ear gathers sound waves in the air?- The auricle or the pinna

2) What name is given to the structure that connects the ear to the nose?

- Eustacian tube3) How does the ear protect itself from unwanted

incoming particles?- The ear wax that lines the auditory canal

4) What two structures compose the inner ear?- The semicircular canals and the cochlea

5) What structure contains the hearing receptor cells?- The cochlea

6) Which part of the hearing system houses the nerve endings for hearing?- The auditory nerve

7) When does a person experience the sensation of hearing?- When the temporal lobe of the brain receives nerve impulses from the auditory nerve

Internet Resources

–Slideshow:• http://www.nlm.nih.gov/medlineplus/tutorial

s/hearingloss/htm/_no_50_no_0.htm