5. Ear, Smell, and Taste

Three Parts of the ear

Outer ear

Middle ear

Inner ear

Outer Ear

1. Auricle; ear

2. External auditory meatus/canal

Contains glands - cerumen gland (wax)

3. Tympanic membrane; ear drum

Middle Ear (tympanic cavity)

Contains ossicles : 3 tiny bones in the middle ear

Eustachian Tube

equalize air pressure between the tympanic cavity and the environment

3 Ossicles

malleus, incus, and stapes

Malleus

First ossicle attached to the tympanic membrane

• transmits its vibrations to the incus

Incus

Middle ossicle, translated the vibration to the staple

Stapes

Third ossicle, that presses on the oval window of the inner ear

Inner Ear (Bony Labyrinth)

Fluid-filled chambers housing receptors for hearing and balance

Inner ear three separate regions

Cochlea(snail shell)

vestibule

Semicircular canals

Membranous Labyrinth

Filled with endolymph

• Cochlear duct, utricle, saccule, semicircular ducts

Endolymph

Fluid within the membranous labyrinth

Inner ear separate region : Vestibule

Central region of the bony labyrinth containing utricle and saccule

Saccule and utricle house equilibrium receptors called ___ which are

Maculae

• clusters of hair cells surrounded by support cells

Inner ear separate region : Semicircular canals

Shake or tilt head represents each canal

• houses equilibrium receptor called crista ampullaris

Crista ampullaris

Receptor for detecting angular movement (tilting head to right)

Each semicircular canal is filled with a fluid known as

Endolymph fluid

Inner ear separate region : cochlea (rolled up like a snail) (3 canals)

Portion responsible for hearing

3 canals :

1. Vestibular duct

2. Tympanic duct

3. Cochlear duct

Sense of smell is

Olfactory

• type of chemoreceptor

• Receptors : in roof of nose

Sense of taste is

What is papillae?

Gustation

• type of chemoreceptor

5 taste sensations : sweet sugar salt butter umani

• contains the taste buds, bumps on our tongue

The process of hearing

step 1

1. Sound waves enter the ear canal, reach the tympanic membrane (eardrum)

Step 2

The tympanic membrane vibrates in response to sound waves

• these vibrations are transferred to the ossicles in the middle ear

Step 3

Ossicles amplify the sound vibrations and the stapes pushed on the oval window (membrane leading to the inner ear)

Step 4

Vibrations create fluid waves in cochlea (snail shell)

Which moves the basilar membrane - stimulated hair cells in the organ of corti

Step 5

Hair cells send signals to the brain (electrical nerve impulses)