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Module 5

Module 5. Sensation. THREE DEFINITONS. Eyes, ears, nose, skin, and tongue are complex, miniaturized, living sense organs that automatically gather information about your environment Transduction

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Module 5

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  1. Module 5 Sensation

  2. THREE DEFINITONS • Eyes, ears, nose, skin, and tongue are complex, miniaturized, living sense organs that automatically gather information about your environment • Transduction • Process in which a sense organ changes, or transforms, physical energy into electrical signals that become neural impulses, which may be sent to the brain for processing • Adaptation • The decreasing response of the sense organs as they’re exposed to a continuous level of stimulation

  3. THREE DEFINITONS (CONT’D) • Sensation versus perception • Relatively meaningless bits of information that result when the brain processes electrical signals that come from the sense organs • Perceptions • Meaningful sensory experiences that result after the brain combines hundreds of sensations

  4. Cocktail-party phenomenon • The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. • Form of selective attention.

  5. Energy v. Chemical senses Energy Senses Chemical Senses

  6. Vision • Our most dominating sense. • Visual Capture

  7. EYE: VISION (CONT’D)

  8. EYE: VISION (CONT’D) • Structure and function • Eyes perform two separate processes • first: gather and focus light into precise area in the back of eye • second: area absorbs and transforms light waves into electrical impulses • Process called transduction

  9. Phase Two: Getting the light in the eye

  10. EYE: VISION (CONT’D) • Retina • Three layers of cells • back layer contains two kinds of photoreceptors that begin the process of transduction • change light waves into electrical signals • rod located primarily in the periphery • cone located primarily in the center of the retina called the fovea

  11. EYE: VISION (CONT’D) • Rods • Photoreceptor that contain a single chemical, called rhodopsin • Activated by small amounts of light • Very light sensitive • Allow us to see in dim light • See only black, white, and shades of gray

  12. EYE: VISION (CONT’D) • Cones • Photoreceptors that contain three chemicals called opsins • Activated in bright light • Allow us to see color • Cones are wired individually to neighboring cells • Allow us to see fine detail

  13. Transduction Continued • Order is Rods/Cones to Bipolar to Ganglion to Optic Nerve. • Sends info to thalamus- area called lateral geniculate nucleus (LGN). • Then sent to cerebral cortexes. • Where the optic nerves cross is called the optic chiasm.

  14. EYE: VISION (CONT’D) • Making colors from wavelengths • Sunlight is called white light because it contains all the light waves • White light passes through a prism; separates light waves that vary in length • Visual system transforms light waves of various lengths into millions of different colors • Shorter wavelengths of violet, blue, green • Longer wavelengths of yellow, orange, and red • An apple is seen as red because reflection of longer light waves that brain interprets as red

  15. EYE: VISION (CONT’D)

  16. Trichromatic Theory Three types of cones: • Red • Blue • Green • These three types of cones can make millions of combinations of colors. • Does not explain afterimages or color blindness well.

  17. Opponent-Process theory The sensory receptors come in pairs. • Red/Green • Yellow/Blue • Black/White • If one color is stimulated, the other is inhibited.

  18. Afterimage

  19. EYE: VISION (CONT’D) • Color blindness • Inability to distinguish two or more shades in the color spectrum • Monochromatic • total color blindness; black and white • result of only rods and one kind of functioning cone • Dichromatic • inherited genetic defect; mostly in males • trouble distinguishing red from green • two kinds of cones • see mostly shades of green

  20. Hearing Our auditory sense

  21. The Ear

  22. EAR: AUDITION • Stimulus • Sound waves • stimuli for hearing (audition) • ripples of different sizes; sound waves travel through space with varying heights and frequency • Height • distance from the bottom to the top of a sound wave; amplitude • Frequency • number of sound waves occurring within a second

  23. EAR: AUDITION (CONT’D) • Loudness • Subjective experience of a sound’s intensity • Brain calculates loudness from specific physical energy (amplitude of sound waves) • Pitch • Subjective experience of a sound being high or low • Brain calculates from specific physical stimuli • Speed or frequency of sound waves • Measured in cycles (how many sound waves in a second)

  24. EAR: AUDITION (CONT’D) • Measuring sound waves • Decibel: unit to measure loudness • Threshold for hearing • 0 decibels (no sound) • 140 decibels (pain and permanent hearing loss)

  25. EAR: AUDITION (CONT’D)

  26. EAR: AUDITION (CONT’D) • Outer, middle, and inner ear • Outer ear • consists of three structures • external ear • auditory canal • tympanic membrane

  27. EAR: AUDITION (CONT’D) • Outer, middle, and inner ear • Outer ear • external ear • oval-shaped structure that protrudes from the side of the head • function • pick up sound waves and then send them down the auditory canal

  28. EAR: AUDITION (CONT’D) • Outer, middle, and inner ear • Outer ear • auditory canal • long tube that funnels sound waves down its length so that the waves strike the tympanic membrane (ear drum)

  29. EAR: AUDITION (CONT’D) • Outer, middle, and inner ear • Outer ear • tympanic membrane • taut, thin structure commonly called the eardrum • sound waves strike the tympanic membrane and cause it to vibrate

  30. EAR: AUDITION (CONT’D) • Outer, middle, and inner ear • Middle ear • bony cavity sealed at each end by membranes that are connected by three tiny bones called ossicles • hammer, anvil, and stirrup • hammer is attached to the back of the tympanic membrane • anvil receives vibrations from the hammer • stirrup makes the connection to the oval window (end membrane)

  31. EAR: AUDITION (CONT’D) • Outer, middle, and inner ear • Inner ear • contains two structures sealed by bone • cochlea: involved in hearing • vestibular system: involved in balance

  32. EAR: AUDITION (CONT’D) • Cochlea • Bony coiled exterior that resembles a snail’s shell • Contains receptors for hearing • Function is transduction • Transforms vibrations into nerve impulses sent to the brain for processing into auditory information

  33. EAR: AUDITION (CONT’D)

  34. EAR: AUDITION (CONT’D) • Auditory cues • Direction of sound • determined by brain; calculates slight difference in time it takes sound waves to reach the two ears • Calculating pitch • frequency theory • applies only to low-pitched sounds • rate ate that nerve impulses reach the brain determines how low a sound’s pitch is • place theory • brain determines medium-to-higher-pitched sounds from the place on the basilar membrane where maximum vibration occurs

  35. EAR: AUDITION (CONT’D) • Auditory cues • Calculating loudness • brain calculates loudness primarily from the frequency or rate of how fast or how slow nerve impulses arrive from the auditory nerve

  36. Vestibular Sense • Tells us where our body is oriented in space. • Our sense of balance. • Located in our semicircular canals in our ears.

  37. VESTIBULAR SYSTEM: BALANCE (CONT’D) • Motion sickness (sensory mismatch between information from the vestibular system) • symptoms: feelings of discomfort, nausea, and dizziness in a moving vehicle • head bouncing, but distant objects look fairly steady • Meniere’s disease (malfunction of the semicircular canals of the vestibular system) • symptoms: dizziness, nausea, vomiting, spinning, and piercing buzzing sounds • Vertigo (malfunction of the semicircular canals of the vestibular system) • symptoms: dizziness and nausea

  38. CHEMICAL SENSES • Taste • Chemical sense because the stimuli are various chemicals • Tongue • Surface of the tongue • Taste buds

  39. CHEMICAL SENSES (CONT’D) • Tongue • Five basic tastes • sweet • salty • sour • bitter • umami: meaty-cheesy taste

  40. CHEMICAL SENSES (CONT’D) • Taste buds • Shaped like miniature onions • Receptors for taste • Chemicals dissolved in saliva activate taste buds • Produce nerve impulses that reach areas of the brain’s parietal lobe • Brain transforms impulses into sensations of taste • Flavor • Combination of taste and smell

  41. Taste • We have bumps on our tongue called papillae. • Taste buds are located on the papillae (they are actually all over the mouth). • Sweet, salty, sour and bitter.

  42. CHEMICAL SENSES (CONT’D) • Smell, or olfaction • Steps for olfaction • stimulus • olfactory cells • sensation and memories • functions of olfaction

  43. CHEMICAL SENSES (CONT’D)

  44. CHEMICAL SENSES (CONT’D) • Smell, or olfaction • Stimulus • we smell volatile substances • volatile substances are released molecules in the air at room temperature • examples: skunk spray, perfumes, warm brownies; not glass or steel

  45. CHEMICAL SENSES (CONT’D) • Smell, or olfaction • Olfactory cells • receptors for smell located in a one-inch-square patch of tissue in the uppermost part of the nasal passages • olfactory cells are covered in mucus that dissolves volatile molecules and stimulates the cells • the cells trigger nerve impulses that travel to the brain, which interprets the impulses as different smells

  46. CHEMICAL SENSES (CONT’D) • Smell, or olfaction • Sensations and memories • nerve impulses travel to the olfactory bulb • impulses are relayed to the primary olfactory cortex • cortex transforms nerve impulses into olfactory sensations • we can identify as many as 10,000 different odors • we stop smelling our deodorants or perfumes because of decreased responding (adaptation)

  47. CHEMICAL SENSES (CONT’D) • Smell, or olfaction • Functions of olfaction • one function: to intensify the taste of food • second function: to warn of potentially dangerous foods • third function: to elicit strong memories; emotional feelings

  48. CHEMICAL SENSES (CONT’D)

  49. TOUCH • Touch • Includes pressure, temperature, and pain • Beneath the outer layer of skin are a half-dozen miniature sensors that are receptors for the sense of touch • Change mechanical pressure or temperature variations into nerve impulses that are sent to the brain for processing

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