Sense Organs

1. Sense Organs The first step in knowing

3. 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

4. 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

5. 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

6. 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

8. 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)

9. 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

10. 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

11. 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

12. 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

13. 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