Hearing

Question 1

What’s the definition of sound?

Answer 1

Vibration with areas of compressions and rarefactions that moves through a medium. The amount of waves that pass from a certain point in a given time

Question 2

What’s a wavelength?

Answer 2

Sound pressure

Question 3

What can sound travel through?

Answer 3

Air, liquids, and solids

Question 4

What are the 3 different frequencies of sound?

Answer 4

Infrasound (<20Hz), Audible frequencies (20Hz-20kHz), and Ultrasound (>20 kHz)

Question 5

What animals can hear ultrasound? Infrasound?

Answer 5

Ultrasound- Bats, Dolphins, Mice, Rats, Some Frogs, Lots of, Insects, Dogs, Cats, and many fish
Infrasound- Elephants, Whales, Giraffes, Okapi, Rhinoceroses, Hippopotamuses, Lots of Frogs, Alligators, and Beavers

Question 6

What are mechanoreceptors basic definition? Used in what?

Answer 6

• Respond to mechanical deformation caused by stimuli such as touch, pressure, stretch, motion, and sound
• Used in proprioception and hearing
• Turn stimulus into chemical signals

Question 7

What are the 4 basic types of mechanoreceptors?

Answer 7

1. Hair (humans)- Tubular body, Lymph space, epithelium and neuron
2. Campaniform (Arthropods)
   Cuticle, neuron, epithelium
3. Chordotonal (Insects and crutaceans)
   Attatchment, cuticle, scolopale, and bipolar neuron
4. Silt (Arachnids)
   Epithelium

Question 8

Describe the hair mechanoreceptor.

Answer 8

• Good in air and fluid

- Deformation triggers ion influx and action potential

Question 9

Describe the campaniform mechanoreceptor.

Answer 9

-Detect stress to cuticle
-Cuticular covering bulges out
-Many on body for proprioception
-On antennae for hearing
Insects

Question 10

Describe the chordotonal mechanoreceptor.

Answer 10

• Stretch receptors

- Can respond to substrate and air vibrations picked up by tympanum (eardrum) or by moving of antenna (flies)

Question 11

Describe the silt mechanoreceptor.

Answer 11

• Only in arachnids (spiders)
• Similar to insect campaniform sensilla
• Many on body for proproiception
• Cuticular covering bulges inward

Question 12

What are statocysts?

Answer 12

• Statoliths – dense particles of calcium carbonate
• Their movement stimulates mechanoreceptors
• Detects gravity
• Found in cnidarians, ctenophores, echinoderms, crustaceans, bivalves and cephalopods

Question 13

What is a hair cell? How are they used in signal transduction?

Answer 13

• Sensory receptors for hearing and equilibrium are hair cells
• Hair cell is slightly depolarized at rest

Question 14

What are the 3 regions of the ear?

Answer 14

• The external ear – collect and channel sound waves
• The middle ear – bony system to amplify vibrations
• The internal ear- generate AP (action potential)

Question 15

What is the external ear anatomy?

Answer 15

The auricle (pinna), a flap of elastic cartilage covered by skin and containing ceruminous glands

Question 16

What is the middle ear anatomy? The 3 bones?

Answer 16

• An air-filled cavity in the temporal bone
• 3 auditory ossicles (bones) in mammals:
  1. The stapes
  2. The incus
  3. The malleus

Question 17

What is the difference between a mammal and reptile middle ear?

Answer 17

-Mammal
3 bones
-Reptile
Only the stapes while the outer ear has the malleus and incus

Question 18

What’s the oval window of the middle ear? Tympanic membrane?

Answer 18

• Oval window – between middle and inner ear
  Covered by stapes

-Tympanic membrane – between outer and middle ear

Question 19

What are the 3 areas of the inner ear? What parts are used for hearing and equilibrium?

Answer 19

(1) the semicircular canals – dynamic equilibrium
(2) the vestibule – static equilibrium
(3) the cochlea - hearing

Question 20

What is the lagena of the inner ear?

Answer 20

• Small extension off the saccule

- Greatly extended into the cochlea in birds and mammals

Question 21

What part of the inner ear contains the hearing apparatus? What 2 types of fluids fill the inner channels?

Answer 21

• Snail shaped cochlea

- perilymph and endolymph

Question 22

How does sound travel through the ear?

Answer 22

1. Sound enters the ear
2. Middle ear bones amplify sound
3. Cochlea sorts sound by frequency

Question 23

How does sound travel through the ear?

Answer 23

1. Sound waves enter the ear canal and strike the tympanic membrane causing vibrations
2. Middle ear bones amplify sound. Malleus moves from vibrations causing the vibrations to go to the incus and then the stapes.
3. Stapes pushes in and out against the oval window transmitting sound waves through the inner ear fluid to basilar membrane in cochlea fluid.
4. Fibres in the membrane vibrate at different frequencies. Base= high; end=low
5. Cochlea hair cells in the organ of corti in the membrane transmit vibrations into electrical impulses

Question 24

How does sound waves turn into chemical signals?

Answer 24

By stimulating the hair cells in the organ or court thus causing electrical impulses sent to the cranial nerve.

Question 25

What modifications do whales and bats have? Explain.

Answer 25

Whales - Sound is conducted to tympanic membrane through jaw and fatty deposits - Similar density to sea water Bats - Echolocation- use of sound waves and echoes to determine where objects are in space - Bats send out sound waves from their mouth or nose. When the sound waves hit an object they produce echoes

Question 26

What is proprioception?

Answer 26

Sense of body position

Question 27

Where are proprioceptors?

Answer 27

In muscles and tendons

Question 28

Where are the proprioceptors information sent? Where is movement initiated?

Answer 28

- To the cerebellum - Movement is initiated in primary motor areas of the brain (cerebrum) - Cerebrum compares intended movement with actual, and fine tunes movements

Question 29

What is equilibrium controlled with? 2 types?

Answer 29

- Vestibular apparatus- Utricle ad Saccule- have hair cells - Static equilibrium - linear acceleration - Dynamic equilibrium - angular acceleration/ rotation

Question 30

What is a otolithic membrane? Role in static equilibrium?

Answer 30

- Studded with CaCO3 crystals (= otoliths) responds to gravity when head position is changed - Movement opens ion channels in hair cells - Tilting head, acceleration, deceleration,

Question 31

Where is dynamic equilibrium controlled? How?

Answer 31

- sensory hairs within semicircular canals - hair cells and supporting cells covered by gelatinous material called the cupula - Ampula at base of canals with hair cells in cupula - Head moves- stimulates cupola which moves endolymph.