Sound Reception

Question 1

What is the subgenual organ ?

Answer 1

The most basic form of reception- All insects
Substrate based communication
Found in the tibia of each leg

Question 2

Describe how the subgenual organ functions.

Answer 2

Leg is filled with Haemolymph
Ground oscillates, foot moves
Compresses haemolymph In lower leg
Whole tibia moves up and down to represent oscillations

Question 3

On which species are Hair-like Sensillae found ?

Answer 3

Insects. Detect airbourne sound

Question 4

What do arachnids have to detect air bourne sounds ?

Answer 4

Trichobothria

Question 5

What are Trichobothria ?

Answer 5

minute hairs which follow the particle movement in air
Hair moves when sound wave
Have mechano-sensory cells at their base.

Question 6

Give a species example of an organisms which uses Trichobothria.

Answer 6

Scorpions, used to catch aerial prey

Question 7

What is the Johnston’s organ ?

Answer 7

Found at the base of a fly antennae

Detects antennal movement

Question 8

How do mosquitoes use the Johnston organ ?

Answer 8

To hear the flight noise of the females

Enables them to mate

Question 9

Tympanal ears have only evolved once in insects

True or False ?

Answer 9

False, they have evolved many times

Question 10

How do Tympanal ears function ?

Answer 10

They measure sound pressure

Most sensitive sound detection

Question 11

Where are Tympanal ears found ?

Answer 11

On many diff. body parts
(Legs, knee)
Tympanal ears evolved from substrate sound

Question 12

How have Tympanal ears evolved to avoid bat predation ?

Answer 12

Are sensitive to ultrasound.

Question 13

What adaption do lacewings have for hearing ?

Answer 13

Small bulbous structure

Acts as an eardrum

Question 14

Describe how the hearing of mammals works.

Answer 14

Pinna collects and funnels sound
Sound waves vibrate tympanic membrane
Ossicles of middle ear transfer vibratory motion of eardrum to oval window of inner ear
Inducing pressure waves in fluid of cohlea
Pressure waves are detected in cochlea by receptor cells in Organ of corti

Question 15

Describe the structures that sound passes through.

Answer 15

Pinna
Tympanic membrane
Ossicles of middle ear 
Inner ear 
Fluid of cochlea 
Cochlea 
Organ of Corti

Question 16

What is the function of the ossicles of the middle ear ?

Answer 16

Are crucial in the transfer of sound from air to fluid

Ossciles of ear transfer vibratory motion of eardrum to oval window of inner ear
Inducing pressure waves in fluid of cochlea

Question 17

What are the pressure waves in the fluid of cochlea detected by ?

Answer 17

Receptor cells in the organ of Corti.

Question 18

What do sound waves vibrate in the ear ?

Answer 18

The tympanic membrane ?

Question 19

What do aquatic mammals mainly receive sounds via ?

Answer 19

Bones and skulls, Not eardrums

Question 20

Describe the sound structures not present in the toothed whales.

Answer 20

No outer and middle ear, no eardrum.

Question 21

What structure is used in the toothed whales to pick up sound ?

Answer 21

The lower Jaw
Fatty tissue & teeth (antennae) also have role

Sound conducting tissue then leads the sound to the inner ear.

Question 22

Describe the structure of the organ of corti.

Answer 22

Basliar membrane upon which outer and inner hair cells sit.
Hair cells found at the end of nerve fibres
All hair cells are connected to the Tectorial membrane.

Question 23

What is the function of the inner hair cells ?

Answer 23

When deformed change rate of neurotransmitter release

This effects the number of Action potentials generated by the sensory neurone.

Question 24

What is the function of the cochlea ?

Answer 24

The pressure wave enters the oval window
Vibrates the basilar membrane and organ of corti
This cause deflection of hair cells and action potentials in neurons.

Question 25

Where is low frequency sound best detected in the cochlea ?

Answer 25

At the apical end of the cochlea

centre of the snail shell

Question 26

Where is high frequency sound best detected in the cochlea ?

Answer 26

At the basal end of the cochlea.

opening of snail shell

Question 27

Outer hair cells are sensory active.

True or False ?

Answer 27

False, Mechanically active

Question 28

Describe the function of the outer hair cells.

Answer 28

Change their length with frequency characteristic for their position along the cochlea
Amplify the weakest sounds.

Question 29

What is the crucial role of the outer hair cells ?

Answer 29

They amplify the weakest sounds.