1. Module 5 Sensation

2. THREE DEFINITONS Adaptation: –the decreasing response of the sense organs, the more they are exposed to a continuous level of stimulation 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

3. THREE DEFINITONS (CONT.) 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

4. EYE: VISION 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

5. EYE: VISION (CONT.) Stimulus: Light Waves –Invisible—too short wave lengths too short gamma rays, x-rays, ultraviolet rays –Visible—just right Visible spectrum Particular segment of electromagnetic energy that we can see because these waves are the right length to stimulate receptors in the eye –Invisible—too long wave lengths longer Radar, FM, TV, shortwave, AM

6. EYE: VISION (CONT.)

7. Structure and function –Vision: 7 steps Image reversed Light waves Cornea Pupil Iris Lens Retina

8. EYE: VISION (CONT.) Structure and function –Image reversed In the back of the eye, objects appear upside down. somehow the brain turns the objects right side up –Light waves light waves are changed from broad beams to narrow, focused ones

9. EYE: VISION (CONT.) Structure and function –Cornea rounded, transparent covering over the front of your eye –Pupil round opening at the front of the eye that allows light waves to pass into the eye’s interior

10. EYE: VISION (CONT.) Structure and function –Iris circular muscle that surrounds the pupil and controls the amount of light entering the eye –Lens transparent, oval structure whose curved surface bends and focuses light waves into an even narrower beam

11. EYE: VISION (CONT.) Structure and function –Retina located at the very back of the eyeball, is a thin film that contains cells that are extremely sensitive to light light sensitive cells, called photoreceptors, begin the process of transduction by absorbing light waves

12. EYE: VISION (CONT.) 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

13. EYE: VISION (CONT.) 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

14. EYE: VISION (CONT.) cones: –photoreceptors that contain three chemicals called opsins –activated in bright light –allow us to see color –cones are wired individually to neighboring cells –allows us to see fine detail

15. EYE: VISION (CONT.) Visual pathways: Eye to brain –Optic nerve –Primary visual cortex –Visual association areas

16. EYE: VISION (CONT.)

17. Visual pathways: eye to brain –Optic nerve nerve impulses flow through the optic nerve as it exits from the back of the eye the exit point is the “blind spot” the optic nerves partially cross and pass through the thalamus the thalamus relays impulses to the back of the occipital lobe in the right and left hemisphere

18. EYE: VISION (CONT.) Visual pathways: eye to brain –Primary visual cortex the back of the occipital lobes is where primary visual cortex transforms nerve impulses into simple visual sensations –Visual association areas the primary visual cortex sends simple visual sensations to neighboring association areas

19. EYE: VISION (CONT.) Color Vision –Trichromatic theory three different kinds of cones in the retina each cone contains one of the three different light- sensitive chemicals, called opsins each of the three opsins is most responsive to wavelengths that correspond to each of the three primary colors blue, green, red all colors can be mixed from these primary colors

20. EYE: VISION (CONT.) Opponent-Process Theory –Afterimage visual sensation that continues after the original stimulus is removed ganglion cells in retina and cells in thalamus respond to two pairs of colors—red-green and blue-yellow when excited, respond to one color of the pair when inhibited, respond to complementary pair

21. EYE: VISION (CONT.) Color Blindness –inability to distinguished 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: trouble distinguishing red from green two kinds of cones inherited genetic defect mostly in males See mostly shades of green

22. EAR: AUDITION Stimulus: –Sound waves ________________________________________ _______________________________________ ________________________________________ –Height ________________________________________ –Frequency ________________________________________

23. EAR: AUDITION (CONT.) Loudness –__________________________________________ –brain calculates loudness from specific physical energy (amplitude of sound waves) Pitch –__________________________________________ –__________________________________________ __________________________________________ __________________________________________

24. EAR: AUDITION (CONT.) Measuring sound waves –decibel: ___________________________________ –threshold for hearing: _______________________________________ ________________________________________ ________________________________________

25. EAR: AUDITION (CONT.)

26. Outer, middle, and inner ear –Outer ear consists of three structures –_____________________________________ –_____________________________________ _____________________________________ _____________________________________

27. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Outer ear external ear –_____________________________________ _____________________________________ _____________________________________ ____________________ function –_____________________________________ _____________________________________ _____________________________________

28. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Outer ear auditory canal –_____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________ _____________________________________

29. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Outer ear tympanic membrane –_____________________________________ _____________________________________ _____________________________________ _____________________________________ –_____________________________________ _____________________________________ _____________________________________ _____________________________________ ________________________

30. EAR: AUDITION (CONT.)

31. Outer, middle, and inner ear –Middle ear bony cavity sealed at each end by membranes. the membranes are connected by three tiny bones called ___________________________________ hammer, anvil and stirrup –_____________________________________ _____________________________________ –_____________________________________ _____________________________________ ________________ –_____________________________________ ____________________________________

32. EAR: AUDITION (CONT.) Outer, middle, and inner ear –Inner ear contains two structures sealed by bone –cochlea: _____________________________________ ________________ –vestibular system: _____________________________________ _____________________________________ _

33. EAR: AUDITION (CONT.) Cochlea –bony coiled exterior that resembles a snail’s shell –contains receptors for hearing –_________________________________________ –transforms vibrations into nerve impulses that are sent to the brain for processing into auditory information

34. EAR: AUDITION (CONT.)

35. Auditory brain areas –sensations and perceptions –two step process occurs after the nerve impulses reach the brain primary auditory cortex –top edge of temporal lobe –transforms nerve impulses into basic auditory sensations –auditory association area combines meaningless auditory sensations into perceptions, which are meaningful melodies, songs, words, or sentences

36. VESTIBULAR SYSTEM: BALANCE Position and balance –vestibular system is located above the cochlea in the inner ear –includes semicircular canals –bony arches set at different angles –each semicircular canal is filled with fluid that moves in response to movements of your head –canals have hair cells that respond to the fluid movement –function of vestibular system include sensing the position of the head, keeping the head upright, and maintaining balance

37. CHEMICAL SENSES Taste –chemical sense because the stimuli are various chemicals

38. CHEMICAL SENSES (CONT.) Tongue –Five basic tastes ___________________________________ ____________________________________ _____________________________________ ________________________________________ ___ ________________________________________ _______________________________________

39. CHEMICAL SENSES (CONT.) Surface of the tongue –________________, which are the stimuli for taste, break down into molecules –molecules mix with ______________ and run into narrow trenches on the surface of the tongue –molecules then stimulate the ____________________

40. CHEMICAL SENSES (CONT.) Taste buds –shaped like miniature onions –_____________________________________ –chemicals dissolved in saliva activate taste buds –__________________________________________ _________________________________________ –___________ transforms impulses into sensations of taste Flavor –__________________________________________

41. CHEMICAL SENSES (CONT.)

42. Smell, or olfaction –Steps for olfaction ______________________________ _____________________________ ___________________________________ ________________________________________

43. CHEMICAL SENSES (CONT.)

44. Smell, or olfaction –Stimulus ____________________________________ volatile substances are released molecules in the air at room temperature example: –_____________________________________ _____________________________________ _____________________________________ _____________________________________ ________________________

45. CHEMICAL SENSES (CONT.) Smell, or olfaction –Olfactory cells receptors for smell are located in a I-inch-square patch of tissue in the uppermost part of the nasal passages. olfactory cells _____________________________ which dissolve volatile molecules and stimulate the cells the cells trigger ______________ that travel to the ____________________________ which interprets the impulses as different smells

46. CHEMICAL SENSES (CONT.) 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 can identify as many as _________ different odors we stop smelling our deodorants or perfumes because of decreased responding called ____________________________

47. CHEMICAL SENSES (CONT.) Smell, or olfaction –Functions of olfaction one function: ____________________________ second function: ________________________________________ ________________________________________ ___________________ third function: ________________________________________ ________________________________________ ________________________________________ ____________________________

48. TOUCH Touch –includes pressure, temperature, and pain

50. TOUCH (CONT.) Receptors in the skin –___________________________________ –____________________________________ –______________________________________ –__________________________________________ __________________________________________

51. TOUCH (CONT.) Skin –________________________________ –thin film of dead cells containing _________________ –just below, are first receptors which look like groups of threadlike extensions –middle and fatty layer –variety of receptors with different shapes and functions –some are ___________________________________

52. TOUCH (CONT.) Hair receptors –___________________ wrapped around the base of each hair follicle –hair follicles fire with a burst of activity when _______ –if hair remains bent for a period of time, the receptors will cease firing –sensory adaptation –example: wearing a watch

53. TOUCH (CONT.) Free nerve endings –__________________________________________ Pacinian corpuscle –_____________________________________ –________________________________________ –__________________________________________ __________________________________________ __________________________________________

54. TOUCH (CONT.) Brain areas –____________________________________ –located in __________________________________ –transforms nerve impulses into __________________________________________ __________________________________________ __________________________________________ __________________________________________ _

55. PAIN What causes pain? –pain: __________________________________________ __________________________________________ __________________________________________ __________________________________________ __________________________________________ __________________________________________ –__________________________________________ __________________________________________ __________________________________________ __________________________________________

57. PAIN (CONT.) How does the mind stop pain? –__________________________________________ __________________________________________ __________________________________________ –Non-painful nerve impulses compete with pain impulses in trying to reach the brain –creates a bottleneck or neutral gate –shifting attention or rubbing an injured area decreases the passage of painful impulses –result: pain is dulled

58. PAIN (CONT.) Endorphins –chemicals produced by the brain and secreted in response to injury or severe physical or psychological stress –pain reducing properties of endorphins are similar to those of morphine –brain produces endorphins in situations that evoke great fear, anxiety, stress or bodily injury as well as intense aerobic activity

59. PAIN (CONT.) Dread –connected to pain centers in brain –not the act itself that people fear –time waiting before event causes dread Acupuncture –trained practitioners insert thin needles into various points on the body’s surface and then manually twirls or electrically stimulates the needles –after 10-20 minutes of stimulation, patients often report a reduction in various kinds of pain