Specific Sensory Systems Special Senses – Hearing and Sound (Audition)

Question 1

What is Hearing and Sound?

Answer 1

• Sound is caused by the vibration or movement of molecules in a medium (i.e., air)
• Where there are no molecules (i.e., in a vacuum) there is no sound

Question 2

Answer 2

make notes

Question 3

What is The Middle Ear?

Answer 3

Middle Ear

• Air-filled cavity
• Contains the malleus, incus and stapes bones
• Amplify sound waves transmitted to the inner ear

Question 4

What is the Inner Ear?
How is is seperated from the middle ear?

Answer 4

• Fluid-filled cavity
• Separated from the middle ear by the oval window

Question 5

How does Sea Level affect the ear?

Answer 5

• Pressure in middle ear and external canal = atmospheric pressure
• Middle ear can equilibrate to atmospheric pressure through the eustachian canal (typically closed, but can be opened in response to yawning, swallowing, sneezing)

Question 6

How do Airplane affect the ears?

Answer 6

• Atmospheric pressure changes ∴ pressure in the middle ear ≠ atmospheric pressure -> pain from stretching of tympanic membrane
• Opening the eustachian canal allows the middle ear to equilibrate to the new atmospheric pressure

Question 7

What are the parts of The Cochlea?

5

Answer 7

Cochlear Duct
Scala Vestibuli and Scala Tympani
Oval and Round windows

Question 8

What is the Cochlear Duct

Answer 8

• Contains sensory receptors of the auditory system
• Contains endolymph – extracellular fluid that is high in
  [K+] and low in [Na+

Question 9

What are the Scala Vestibuli and Scala Tympani?

Answer 9

• Above and below cochlear duct respectively
• Continuous at helicotrema
• Filled with perilymph

Question 10

What are teh Oval and Round windows?

Answer 10

• Membrane covered openings that connect the middle with the inner ear

look into

Question 11

What is The Basilar Membrane?

Answer 11

• Side of cochlear duct adjacent to Scala tympani
• Organ of Corti found here (contains receptor cells sensitive to sound waves)

Answer 12

Question 13

What is the Pathway of Sound Waves?

Answer 13

1. Sound Waves are deflected by the Tympanuc membrane &
2. causes the middle ear bones and membrane in oval window to move
3. The pressure waves travel through the perilymph of scala vestibuli and return to round window through scala tympani
4. CONTINUE

Question 14

What are the Mechanoreceptor cells of the ear?

Answer 14

Hair Cells of the Organ of Corti

• One layer of inner hair cells
• Three layers of outer hair cells

Question 15

What is stereocilia?

Answer 15

On hair cells, Contain stereocilia protruding from one end

• Stereocilia of inner hair cells extend to endolymph and move in response to fluid movement, generating receptor potential

Question 16

Explain whats happening here

Question 17

How do we get a greater frequency of action potentials?

Answer 17

Greater the energy of sound -> greater frequency of action potentials

Question 18

What are Cochlear nerves?

Answer 18

brainstem and synapse there (fibres from both ears typically converge on the same neuron) -> thalamus -> auditory cortex in the temporal lobe

Question 19

What would the effect on hearing be if the tip links between the sterocelia of hair cells snapped?

Answer 19

ion channels cant open to depolarize the cell and generate an action potential that allow us to perceive sound