Hearing Flashcards
What’s the definition of sound?
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
What’s a wavelength?
Sound pressure
What can sound travel through?
Air, liquids, and solids
What are the 3 different frequencies of sound?
Infrasound (<20Hz), Audible frequencies (20Hz-20kHz), and Ultrasound (>20 kHz)
What animals can hear ultrasound? Infrasound?
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
What are mechanoreceptors basic definition? Used in what?
- 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
What are the 4 basic types of mechanoreceptors?
- Hair (humans)- Tubular body, Lymph space, epithelium and neuron
- Campaniform (Arthropods)
Cuticle, neuron, epithelium - Chordotonal (Insects and crutaceans)
Attatchment, cuticle, scolopale, and bipolar neuron - Silt (Arachnids)
Epithelium
Describe the hair mechanoreceptor.
- Good in air and fluid
- Deformation triggers ion influx and action potential
Describe the campaniform mechanoreceptor.
-Detect stress to cuticle
-Cuticular covering bulges out
-Many on body for proprioception
-On antennae for hearing
Insects
Describe the chordotonal mechanoreceptor.
- Stretch receptors
- Can respond to substrate and air vibrations picked up by tympanum (eardrum) or by moving of antenna (flies)
Describe the silt mechanoreceptor.
- Only in arachnids (spiders)
- Similar to insect campaniform sensilla
- Many on body for proproiception
- Cuticular covering bulges inward
What are statocysts?
- Statoliths – dense particles of calcium carbonate
- Their movement stimulates mechanoreceptors
- Detects gravity
- Found in cnidarians, ctenophores, echinoderms, crustaceans, bivalves and cephalopods
What is a hair cell? How are they used in signal transduction?
- Sensory receptors for hearing and equilibrium are hair cells
- Hair cell is slightly depolarized at rest
What are the 3 regions of the ear?
- The external ear – collect and channel sound waves
- The middle ear – bony system to amplify vibrations
- The internal ear- generate AP (action potential)
What is the external ear anatomy?
The auricle (pinna), a flap of elastic cartilage covered by skin and containing ceruminous glands
What is the middle ear anatomy? The 3 bones?
- An air-filled cavity in the temporal bone
- 3 auditory ossicles (bones) in mammals:
1. The stapes
2. The incus
3. The malleus
What is the difference between a mammal and reptile middle ear?
-Mammal
3 bones
-Reptile
Only the stapes while the outer ear has the malleus and incus
What’s the oval window of the middle ear? Tympanic membrane?
- Oval window – between middle and inner ear
Covered by stapes
-Tympanic membrane – between outer and middle ear
What are the 3 areas of the inner ear? What parts are used for hearing and equilibrium?
(1) the semicircular canals – dynamic equilibrium
(2) the vestibule – static equilibrium
(3) the cochlea - hearing
What is the lagena of the inner ear?
- Small extension off the saccule
- Greatly extended into the cochlea in birds and mammals
What part of the inner ear contains the hearing apparatus? What 2 types of fluids fill the inner channels?
- Snail shaped cochlea
- perilymph and endolymph
How does sound travel through the ear?
- Sound enters the ear
- Middle ear bones amplify sound
- Cochlea sorts sound by frequency
How does sound travel through the ear?
- Sound waves enter the ear canal and strike the tympanic membrane causing vibrations
- Middle ear bones amplify sound. Malleus moves from vibrations causing the vibrations to go to the incus and then the stapes.
- Stapes pushes in and out against the oval window transmitting sound waves through the inner ear fluid to basilar membrane in cochlea fluid.
- Fibres in the membrane vibrate at different frequencies. Base= high; end=low
- Cochlea hair cells in the organ of corti in the membrane transmit vibrations into electrical impulses
How does sound waves turn into chemical signals?
By stimulating the hair cells in the organ or court thus causing electrical impulses sent to the cranial nerve.
What modifications do whales and bats have? Explain.
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
What is proprioception?
Sense of body position
Where are proprioceptors?
In muscles and tendons
Where are the proprioceptors information sent? Where is movement initiated?
- To the cerebellum
- Movement is initiated in primary motor areas of the brain (cerebrum)
- Cerebrum compares intended movement with actual, and fine tunes movements
What is equilibrium controlled with? 2 types?
- Vestibular apparatus- Utricle ad Saccule- have hair cells
- Static equilibrium - linear acceleration
- Dynamic equilibrium - angular acceleration/ rotation
What is a otolithic membrane? Role in static equilibrium?
- Studded with CaCO3 crystals (= otoliths) responds to gravity when head position is changed
- Movement opens ion channels in hair cells
- Tilting head, acceleration, deceleration,
Where is dynamic equilibrium controlled? How?
- 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.
