Download The first step in knowing

Sense Organs
The first step in knowing
What does it mean to hear?
• Sound waves traveling through the air
• Changes in air pressure that result from
vibration
– Each vibration is called a cycle or sound wave
What is frequency
• Every sound has its own pitch and loudness
– Depends on frequency (cycle per second)
– Low sounds low frequency
– High sounds high frequency
• Examples
– Woman’s voice=shorter vocal chords ; Man’s voice
=longer vocal chords
– Violin has shorter strings than a cello
• Human hearing 20 to 20,000 cycles per
second; Dogs, dolphins hear more cycles
What is sound?
• Determined by height (amplitude of waves)
– Higher the amplitude the louder the sound
– Softer sounds have less amplitude
• Measured in decibels (height of wave)
• Ear needs time to adjust to louder sounds
• Zero dB = absolute threshold for hearing
– Ticking watch 20ft away
• 90 db beginnings of hearing loss can occur
– Train whistle, lawn mower
Parts of the Ear
• Outer ear
– pinna (outside of the skull)
• Middle ear
– ear drum & bones (hammer, anvil, stirrup)
• Inner ear
– cochlea (snail shape tube that contains fluid &
neurons)
– Moves in response to vibrations
– Movement transmits neural impulses along
auditory nerve to the brain
Hearing & deafness
• We locate sounds by repositioning the head & ears
• Sensorineural deafness
– Damage to inner ear
– Loss of neurons in cochlea
– Result of disease or prolonged exposure to loud
sounds
– Can only be corrected if people have memories of
sound
• Conductive deafness
– Damage to middle ear
– As long as auditory nerve is intact it is possible for
most people to hear
– Use hearing aid to increase amplitude (loudness)
Smell & Taste
• Odors are detected by receptor neurons in each
nostril
• Info is sent via the olfactory nerve
• Taste has 4 qualities
• Sweet, sour, salty, bitter (umami=savory)
• Apples & onions taste similar, it is their odor that
makes their flavors different
• Taste buds –receptor neurons
• Taste sensitivities can be inherited
– Few people ever lose their sense of taste
– You grow new taste buds throughout your life
Skin & Touch
• Skin senses are a combination of pressure,
temperature & pain
– Reduces stress & depression
– Can help babies thrive
• Extremities and face more sensitive than
thighs, calves, upper arms and shoulders
• Different receptors fire for cold & hot
• The more pain receptors in our skin, the more
sensitive the area
How do pain messages travel?
• Pain in contact area ->spinal chord ->thalamus
->projected on to cerebral cortex ->
brain registers sensitivity & location ->
prostaglandins produce & transmit pain
messages to the brain
• Ibuprofin & aspirin stop production of
prostaglandins
Why we do or do not feel pain
• Gate Theory: rubbing or scratching sends
competing messages with pain messages
– Prevents some of the pain messages from getting
through
• Phantom pain: people who lose a limb or loss
of feeling have memories of pain that are
activated by nerve endings near the location
of the original injury
Vestibular Sense
• Vestibular sense tells you whether or
not you are upright
– Helps keep you balanced
– Lets you know if you are falling
• Kinesthesis: sense that informs you
about the position & motion of their
bodies
– Athletes and musicians typically have
more kinesthetic sense than others