Sensory System - The Ears

Question 1

How can animals hear sound?

Answer 1

sounds are vibrations of air molecules

it is these vibrations that the ear can detect

the ear then turns these vibrations into electrical signals that are then sent to the brain

the brain then interprets these electrical signals as sounds animals can hear

Question 2

Why does noise sound different in water?

Answer 2

sound in water is the result of vibrations of water molecules

these vibrations are different to those in air

Question 3

What are the names of the three parts of a mammal’s ear?

Answer 3

the outer ear
the middle ear
the inner ear

Question 4

What makes up the outer ear?

Answer 4

pinna
auditory meatus

Question 5

What is the pinna?

Answer 5

the visible portion of the ear whose shape helps to direct sound into the ear and amplify the important pitches

Question 6

What is the auditory meatus or ear cannal?

Answer 6

a passageway that connects the pinna to the middle ear

channels sound through the middle ear

Question 7

What makes up the middle ear?

Answer 7

tympanic membrane
malleus
incus
stapes

Question 8

What is the tympanic membrane or eardrum?

Answer 8

a very thin surface connected to the auditory meatus

vibrations of air within the auditory meatus causes the surface of the tympanic membrane to vibrate

Question 9

What is the malleus?

Answer 9

the first of the three bones in the ear

hammer-shaped and attached to the tympanic membrane

Question 10

What is the incus?

Answer 10

the second of the three bones in the ear

anvil-shaped bone that sits between and is connected to the malleus and stapes

Question 11

What is the stapes?

Answer 11

the third of the three bones in the ear

stirrup-shaped bone that is connected to the incus and the oval window

Question 12

How do vibrations from the tympanic membrane get to the inner ear?

Answer 12

vibrations are transmitted by the malleus, incus and stapes and transmitted to the oval window

Question 13

What increases hearing sensitivity?

Answer 13

the middle ear acts like an amplifier

the pressure of vibrations on the oval window is much higher than on the tympanic membrane

Question 14

What is the middle ear also connected to?

Answer 14

the throat via the eustachian tube

this prevents pressure or fluid building up in the ear

Question 15

What makes up the inner ear?

Answer 15

oval window
round window
semi-circular canals
cochlea
organ of corti
cochlear nerve

Question 16

What is the oval window?

Answer 16

a membrane-covered opening that connects the stapes to a fluid-filled cavity within the cochlea

connects the middle ear to the inner ear

vibrations from the stapes causes the oval window to vibrate

Question 17

What is the round window?

Answer 17

a membrane-covered opening of the cochlea

allows the fluid within the cochlea space to move

Question 18

What are the semi-circular canals?

Answer 18

control balance

have nothing to do with hearing

each of the three semi-circular canals has a different orientation and each is filled with fluid

movement of the fluid in each stimulates hair-like protrusions which generates electrical signals which are sent to the brain

differences between signals from the three canals are interpreted by the brain and used to coordinate position and balance

Question 19

What is the cochlea?

Answer 19

central organ of the inner ear

spiral-shaped structure that is filled with a fluid which vibrates whenever the oval window vibrates

in the middle is a membrane

the vibrations of fluid within the cochlea cause vibrations in particular sections of this membrane

Question 20

What do slow vibrations within the cochlea cause within the membrane?

Answer 20

the wide part of the membrane to move, but the rest of the membrane does not move

Question 21

What do fast vibrations within the cochlea cause within the membrane?

Answer 21

the narrow part of the membrane to move but the rest of the membrane does not

Question 22

What is the organ of corti?

Answer 22

attached to the membrane in the cochlea

consists of special cells with hair-like projections all along the membrane

these hairs are stimulated to send electrical signals by the movement of the part of the membrane to which they are attached

all the electrical signals are sent from the cells to the cochlear nerve

Question 23

What is the cochlear nerve?

Answer 23

carries all of the electrical signals gathered from the organ of corti and transports them to the brain for interpretation as sounds

Question 24

What animals don’t have ears?

Answer 24

birds, fish, amphibians and reptiles

Question 25

What other functions does the pinna have?

Answer 25

regulates body temperature

an elephant’s large pinna helps it to keep cool

Question 26

What adaptations do predatory species have?

Answer 26

forward-facing ears

slight differences between the sounds in each ear allows them to pinpoint the exact location of the sound

Question 27

What adaptations do prey species have?

Answer 27

moveable ears so that the animal can point their ears in a range of directions to ensure nothing sneaks up on them