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EAR
• The ear is a sense organ for hearing and
balance
• Three main portions of ear
– Outer Ear : containing air
– Middle ear : containing air
– Inner ear : containing fluid
• Only mammals contain ear lobes
Parts of ear
Structure
Function
Pinna
Fleshy part seen
in the side of the
head
Passage which
leads to the
eadrum
Direct sound
waves in to the
auditory canal
Directs sound
wave to he
eardrum
Auditory canal
Parts of
ear
Structure
Eardrum
A thin membrane
(tympanum)
Function
Vibrates when it receive the sound
waves and passes the vibration to
the ear ossicles
Ear ossicles
A chain of three small bones
Magnify the sound vibrations and
connecting the eardrum to the pass them on to the cochlea through
oval window
the oval window
Oval
window
A thin membrane
Transfers the sound vibrations from
ear ossicles to the cochlea
Round
window
A thin membrane below the
oval window
Help sound vibrations to pass
through the cochlea
Eustachian
tube
An air passage leading from
the middle ear to the throat
Helps to equalise the air pressure on
each side of the eardrum
Parts of
ear
Structure
Function
Cochlea
A coiled tube with sensory
cells and filled with fluid
Changes sound vibrations
into nervous impulses for
transmission to the brain
Auditory
nerve
A bundle of nerves
connecting the cochlea to
the brain
Carries nervous impulses
from the cochlea to the brain
Semicircular
canals
Three canals containing a
fluid which swirls when the
head is moved
Help the body to maintain
balance
Hearing Machanism
Pinna- directs sound waves into the
auditory canal
Auditoty canal- directs sound waves to
the eardrum
Eardrum- vibrates at the same speed as
the sound wave
Ear-ossicles- magnify the sound
vibrations and make the oval window
vibrate at the same frequency
Oval window- vibrates and makes the
fluid in the cochlea vibrate
Cochlea- changes the sound vibrations
into nervous impulses
Auditory nerve- transmits the nervous
impulses from the cochlea to the brain
The brain- interprets the nervous
impulses as sounds
Spot test
1. What’s the taste detected by the regions
below?
2. State the 2 components which make up the
central nervous system.
3. State the 2 types of nerves.
4. State 5 types of receptors in the skin and their
function.
5. What’s the 2 factors which affect the sensitivity
of the skin?
6. What’s function of the sweat glands in the skin?
7. What is mucus?
8. How can a common cold decrease our sense of
smell?
9. Why is the sense of taste called a chemical
sense?