COM S6 Flashcards
Outline and compare the detection of vibrations by insects, fish and mammals
Hearing ability to detect sound waves by changing the vibrations of sound to electrical energy of nerves
Outline and compare the detection of vibrations by insects, fish and mammals (Insect)
• Only some can hear Crickets, grasshoppers, cicadas, butterflies, moths & flies
• Body hairs may vibrate in response to sound waves
• Male mosquitos hairs on antennae that vibrate in response to wing vibrations of flying female mosquitos brings together for mating
• Tympanic organ (some insects) detects vibrations
Tympanic membrane stretched across internal chamber
Sound waves vibrate membrane stimulates receptor cells on inside membrane or within chamber
• Crickets ears on legs
• Grasshoppers & cicadas ears on abdomens
Outline and compare the detection of vibrations by insects, fish and mammals (Fish)
• Lateral line system on side of body – detects:
Fish’s movement in water
Direction and speed of current
Vibrations from surrounding objects
Low-frequency sound waves
• Receptor cells detect movement water flowing through bends hair cells produces nervous impulses sent to brain
• Inner ears near the brain
Vibrations conducted through skeleton and bladder
Receptors respond to higher frequencies
Outline and compare the detection of vibrations by insects, fish and mammals (Mammals)
• Ears main organ to detect vibrations
• Vibrations detected by hair cells in internal structures due to vibrations of membranes & amplification from outside to inner ear
• Used for communication
• Echolocation:
Detect size, position & movement of close objects
Used in sperm whales, bats and dolphins
Structures of the outer ear?
Pinna, Tympanic Membrane
Pinna, its anatomy and function
• Large fleshy external part
- Collects sound waves from wide area (environment)
- Directs sound into ear
- Waves = vibration of air molecules
- Waves continue along canal known as external auditory meatus
Tympanic membrane, its anatomy and function
- Ear drum
- Stretches tightly across end of auditory canal
- Sound waves cause it to vibrate vibrations travel to oval window by ear ossicles
- Separates outer and middle ear
Name the structures of the middle ear.
Ear ossicles, Oval window, Round window
Ear ossicles, its anatomy
- Three tiny bones
* Malleus (hammer), incus (anvil) and stapes (stirrups)
Oval window, its anatomy
- Small, thin membrane between middle and inner ear
* Links ossicles with cochlea
Round window, its anatomy
- Located below oval window
* Membrane between middle ear and cochlea
Ear ossicles, its function
- Transmit sound waves to inner ear (vibrations travel well through bone)
- Tympanic membrane kept tense by malleus sound vibrating through membrane transmitted to malleus into inner ear
- Eardrum vibrates ossicles vibrate amplifying the sound and transmitting to oval window
- Stapes connects with oval window movement of inner ear fluid
Oval Window, its function
- Receives vibration from tympanic membrane via ossicles much greater force
- Passes vibrations onto fluid in cochlea
- Amplifies pressure of sound
Round window, its function
• Bulges outward to allow pressure release in cochlea
Name the structures of the inner ear.
Cochlea, Organ of Corti, Auditory nerve
Cochlea, its anatomy
- Fluid-filled chamber
- Snail-like spiral coiled tube
- Three tubular chambers
- 35mm long
- 1st & 2nd chambers separated by Reissner’s membrane
- 2nd & 3rd chambers separated by basilar membrane
Cochlea, its function.
- Contains receptors for sound
- Vestibular apparatus balance
- Round window bulging outwards fluid in cochlear vibrates
- Changes mechanical energy into electrochemical energy
Organ of Corti, its anatomy
- On basilar membrane in cochlea
* Contains auditory receptor cells
Organ of Corti, its function
- Hair cells receptor cells – detect vibrations & generate nerve impulses travel via auditory nerve to brain
- Transfer vibrations into electrochemical signals
Auditory Nerve, its anatomy
• Nerve travelling from ear to brain
Auditory nerve, its function
• Transmits electrochemical signals to brain
Outline the role of the Eustachian tube
- Connects the middle ear to the pharynx (chamber at nose and throat)
- Usually closed can be opened by yawning or swallowing
- Connects to air-filled space Equalise the pressure on either side of tympanic membrane (ear drum)
Outline the path of a sound wave through the external, middle and inner ear and identify the energy transformations that occur
- Sound waves collected by the pinna auditory canal tympanic membrane (vibrates at same frequency as sound)
- First ossicle (malleus) attached to tympanic membrane bone vibrates, amplifies vibration passes onto two other ossicles, amplify vibration
- Last ossicle (stapes) attached to oval window vibrates fluid in cochlea vibrates
- Sound energy converted to mechanical energy
- As oval window bulges into inner ear causes waves in fluid bends hair cells
- Hair cells of organ of Corti detect vibration stimulate nerve impulses
- Mechanical energy converted into electrochemical energy pass message to cerebrum in brain via auditory nerve
Whats the organ of corti?
- Organ of Corti ribbon-like structure in cochlea
- Sound receptor = hair cells
- Includes: Basilar membrane – hair cells – tectorial membrane
Whats the Basilar membrane?
Have hair cells of different lengths
Vibrations from oval window transmitted through cochlea fluids hair cells vibrate according to frequency
High frequency sounds cause short hair cells at front of membrane (nearest to oval window) to vibrate
Low frequency sounds stimulate long hair cells at end of membrane (travel to end)
Describe the relationship between the distribution of hair cells in the organ of Corti and the detection of sounds of different frequencies
• As basilar membrane vibrates hair cells of organ of Corti pushed against tectorial membrane hair cells send electrochemical impulse along auditory nerve to brain
• Organ of Corti = distinguishes sounds of different frequencies sending pattern to brain of vibrations
Sends information on intensity and duration of sound
• Round window = vibrations stop
Bulges outwards as waves reach it
outline the range of frequencies detected by humans as sound and compare this range with two other mammals, discussing possible reasons for the differences identified
- Human frequency range = 20-23000 Hz
- Range of frequencies heard varies from species to species
Mammal Lowest frequency detected > Highest frequency detected (Hz) Human 20-23 000 Dog 67-45 000 Whale 1000-123 000 Bats 100 000-120 000
• Reasons for differences:
Very high sounds (used by bats) allow for precise echolocation
Whales need to communicate over large distances low sounds travel long way underwater
Mammal Lowest frequency detected > Highest frequency detected (Hz)
Human 20-23 000
Dog 67-45 000
Whale 1000-123 000
Bats 100 000-120 000
Outline the role of the sound shadow cast by the head in the location of sound
- Head casts sonic shadow between sound source and furthest ear away from the sound
- One ear receives less sound than the other
- Humans usually turn head to locate sound
- Sound coming from right reaches right ear then blocked by head
- To reach left ear sound waves must travel around or through head
- Head absorbs high frequencies easily than low ones creates sound shadow for ear furthest away from sound source
- Small difference in perception by each ear brain can interpret direction
- When sound comes from in front or behind both ears receive same stimulus
Hearing aid, where is the device placed?
• Fit into hollow outside ear canals Pinna • Battery-operated • Consists of Microphone to capture sounds Amplifier to magnify sounds Earphone to channel into ear
Hearing aid, position and type of energy transfer occurring?
- Helps in converting sound energy into electrical energy
- Sound waves sent to amplifier Amplify sounds
- Amplified sound waves sent to sensory hair cells in organ of Corti convert into electrical impulses
Hearing aid, Conditions under which the technology will assist hearing?
• People with sensorineural hearing loss
Develops when auditory nerve or hair cells damaged by aging, noise, illness etc
• Recipient must have some hearing left Can only amplify sound
• Greatly improve comprehension, speech and low frequency discrimination
Hearing aid, Limitations of each technology
- Limited assistance in high frequency ranges
- Amplification Loud noises = annoying
- Batteries may run out BUT most models give adequate warning of dying batteries
- Do not assist in nerve deafness caused by damage to inner ear, auditory nerve or auditory centre of the brain
Cochlear implant, Where is the device placed?
Surgically placed under the skin behind the ear & Transmitter on outside
Cochlear Implant, Position and type of energy transfer occurring
- Sound waves microphone & speech processor
- Transmitter Receiver Cochlear direct to auditory nerve
- Energy transfer: Sound energy electrical energy radio waves electrical signals electrochemical
Cochlear Implant, Conditions under which the technology will assist hearing?
• Hair cell damage causes hearing loss
Hair cells convert sound energy into electrical energy that can stimulate auditory nerve
• Deaf people
• Works best where people lost their hearing after they learnt to speak
Cochlear Implant, Limitations of each technology
- Only 80% effective
- Risks involved with surgical insertion of implants
- Cost: surgery expensive and on-going costs
- Surgery side-effects: droopy face and numb tongue
- Adjustment to different lifestyle and sensation of hearing sounds difficult
