1. © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 29 The Senses

2. Introduction  Bats use echolocation to detect their environment.  High-pitched sounds are –produced in their larynges (singular, larynx) and –emitted from their mouths and noses.  Their brains process the time delay and spatial arrangement of the echoes to determine the size, shape, location, speed, and direction of objects in their environment. © 2012 Pearson Education, Inc.

3.  Marine mammals –include dolphins, killer whales, and sperm whales, –produce ultrasonic clicking sounds in their nasal passages, –focus the sound by bouncing it off of skull bones and an oil-filled structure in their forehead, and –receive the echo in a narrow window of bone behind the jaw.  Echolocation has also been observed in some species of cave-dwelling birds and forest-dwelling shrews. Introduction © 2012 Pearson Education, Inc.

4. Figure 29.0_1 Chapter 29: Big Ideas Sensory Reception Hearing and Balance Taste and SmellVision

5. Figure 29.0_2

6. SENSORY RECEPTION © 2012 Pearson Education, Inc.

7. 29.1 Sensory organs share a common cellular basis  All animal senses originate in sensory receptors, specialized cells or neurons that are tuned to the –conditions of the external world and –the internal organs.  All sensory receptors –trigger an action potential and –send information to the central nervous system. –Sensation depends on the part of the brain that receives the action potential. © 2012 Pearson Education, Inc.

8. Figure 29.1

9. 29.2 Sensory receptors convert stimulus energy to action potentials  Sensory receptors detect stimuli.  All stimuli represent forms of energy.  In a process called sensory transduction, receptors –detect one type of signal (the stimulus) and –convert the signal to another type, an electrical signal. © 2012 Pearson Education, Inc.

10.  When a sensory receptor cell in a taste bud detects sugar molecules, 1.sugar molecules enter the taste bud, 2.sugar molecules bind to sweet receptors, specific protein molecules embedded in a taste receptor cell membrane, and 3.the binding triggers a signal transduction pathway that causes some ion channels in the membrane to close and others to open. 4.These changes in the flow of ions create a graded change in membrane potential called a receptor potential. 29.2 Sensory receptors convert stimulus energy to action potentials © 2012 Pearson Education, Inc.

11. Figure 29.2A Sugar molecule Sensory receptor cells Taste pore Taste bud Sensory neuron Sugar molecule (stimulus) Membrane of a sensory receptor cell Sweet receptor Signal transduction pathway Ion channels Ion Sensory receptor cell Receptor potential Neurotransmitter Sensory neuron Action potential to the brain 5 4 3 2 1 6 No sugarSugar present Rates of action potentials mV

12. Figure 29.2A_1 Sugar molecule Sensory receptor cells Taste pore Taste bud Sensory neuron 1

13. Figure 29.2A_2 Sugar molecule (stimulus) Membrane of a sensory receptor cell Sweet receptor Signal transduction pathway Ion channels Ion Sensory receptor cell 2 3 4

14. Figure 29.2A_3 Receptor potential Neurotransmitter Sensory neuron Action potential to the brain No sugar Sugar present Rates of action potentials mV Ion channels Ion Sensory receptor cell 4 5 6

15.  The stronger the stimulus, –the more neurotransmitter released by the receptor cell and –the more frequently the sensory neuron transmits action potentials to the brain.  Repeated stimuli may lead to sensory adaptation, the tendency of some sensory receptors to become less sensitive when they are stimulated repeatedly. 29.2 Sensory receptors convert stimulus energy to action potentials © 2012 Pearson Education, Inc.

16. Figure 29.2B “Sugar” interneuron Sugar receptor cell Taste bud Brain Sensory neurons Salt receptor cell “Salt” interneuron Taste bud No sugar No salt Increasing sweetnessIncreasing saltiness

17. 29.3 Specialized sensory receptors detect five categories of stimuli  There are five categories of sensory receptors. 1. Pain receptors detect dangerous stimuli including high heat and pressure. 2. Thermoreceptors detect heat or cold. 3. Mechanoreceptors respond to –mechanical energy, –touch, –pressure, and –sound. © 2012 Pearson Education, Inc.

18. 4. Chemoreceptors –include sensory receptors in our nose and taste buds and –respond to chemicals. 5. Electromagnetic receptors respond to –electricity, –magnetism, and –light (sensed by photoreceptors). 29.3 Specialized sensory receptors detect five categories of stimuli © 2012 Pearson Education, Inc.

19. Figure 29.3A HeatLight touch Epidermis PainCold Hair Dermis Nerve to brain Connective tissue Hair movement Strong pressure

20. Figure 29.3B “Hairs” of a receptor cell Fluid movement Neurotransmitter at a synapse Sensory neuron Action potentials Action potentials Receptor cell at restFluid moving in one directionFluid moving in the other direction More neurotransmitter molecules Fewer neurotransmitter molecules Fluid movement 321

21. Figure 29.3B_1 “Hairs” of a receptor cell Neurotransmitter at a synapse Sensory neuron Action potentials Action potentials Receptor cell at rest 1

22. Figure 29.3B_2 Fluid movement Fluid moving in one direction More neurotransmitter molecules 2

23. Figure 29.3B_3 Fluid moving in the other direction Fewer neurotransmitter molecules Fluid movement 3

24. Figure 29.3C

25. Figure 29.3C_1

26. Figure 29.3C_2

27. Figure 29.3D Infrared receptor

28. HEARING AND BALANCE © 2012 Pearson Education, Inc.

29. 29.4 The ear converts air pressure waves to action potentials that are perceived as sound  The human ear channels sound waves –from the outer ear with a flap-like pinna, –down the auditory canal, –to the eardrum, which separates the outer ear from the middle ear, –to a chain of bones in the middle ear (malleus, incus, and stapes), and –to the fluid in the coiled cochlea in the inner ear. –The Eustachian tube connects the pharynx to the middle ear, permitting pressure equalization. © 2012 Pearson Education, Inc.

30. Figure 29.4A Outer ear Inner ear Pinna Auditory canal Eardrum Middle ear Eustachian tube

31.  Pressure waves transmitted to the fluid of the cochlea –bend hair cells in the organ of Corti against the basilar membrane and –trigger nerve signals to the brain.  Louder sounds generate more action potentials.  Various pitches stimulate different regions of the organ of Corti. 29.4 The ear converts air pressure waves to action potentials that are perceived as sound © 2012 Pearson Education, Inc.

32. Figure 29.4B Skull bones Semicircular canals (function in balance) Auditory nerve, to the brain Cochlea Eustachian tube (connects to the pharynx) Eardrum Stirrup Anvil Hammer Oval window (behind the stirrup)

33. Figure 29.4C Middle canal Bone Upper canal Auditory nerve Lower canal Organ of Corti

34. Figure 29.4D Hair cells Tectorial membrane Sensory neurons To the brain via the auditory nerve Basilar membrane

35. Figure 29.4E Outer EarMiddle EarInner Ear Cochlear canals Upper and middleLower Oval window Hammer, anvil, stirrup Ear- drum Auditory canal Pinna Pressure One vibration Amplitude Concentration in the middle ear Organ of Corti stimulated Time

36. Figure 29.4E_1 Outer EarMiddle EarInner Ear Cochlear canals Upper and middle Lower Oval window Hammer, anvil, stirrup Ear- drum Auditory canal Pinna Pressure One vibration Amplitude Concentration in the middle ear Organ of Corti stimulated Time

37.  Deafness is the loss of hearing.  Deafness can be caused by the inability to detect sounds resulting from –middle-ear infections, –a ruptured eardrum, or –stiffening of the middle-ear bones.  Deafness –can also result from damage to sensory receptors or neurons and –is often progressive and permanent. 29.4 The ear converts air pressure waves to action potentials that are perceived as sound © 2012 Pearson Education, Inc.

38. 29.5 The inner ear houses our organs of balance  Three organs in the inner ear detect body position and movement. These include –three semicircular canals and –two chambers, the utricle and the saccule. –All three of these structures operate on the same principle: the bending of hairs on hair cells.  The three semicircular canals detect changes in the head’s rotation or angular movement.  The utricle and saccule detect the position of the head with respect to gravity. © 2012 Pearson Education, Inc.

39. Figure 29.5 Semicircular canals Nerve Cochlea Saccule Utricle Flow of fluid Cupula Flow of fluid Cupula Hairs Hair cell Nerve fibers Direction of body movement

40. Figure 29.5_1 Semicircular canals Nerve Cochlea Saccule Utricle

41. Figure 29.5_2 Flow of fluid Cupula Flow of fluid Cupula Hairs Hair cell Nerve fibers Direction of body movement

42. 29.6 CONNECTION: What causes motion sickness?  Motion sickness may be caused by conflicting signals between the –inner ear and –eyes.  Motion sickness can be a severe problem for astronauts. © 2012 Pearson Education, Inc.

43.  Motion sickness may be reduced by –closing the eyes, –limiting head movements, –focusing on a stable horizon, –sedatives such as dramamine or bonine, or –long-lasting, drug-containing skin patches. 29.6 CONNECTION: What causes motion sickness? © 2012 Pearson Education, Inc.

44. VISION © 2012 Pearson Education, Inc.

45. 29.7 EVOLUTION CONNECTION: Several types of eyes have evolved independently among animals  The ability to detect light plays a central role in the lives of nearly all animals.  All animal light detectors are based on cells called photoreceptors that contain pigment molecules that absorb light. © 2012 Pearson Education, Inc.

46. 29.7 EVOLUTION CONNECTION: Several types of eyes have evolved independently among animals  Most invertebrate eyes include some kind of light- detecting organ.  One of the simplest organs is the eye cup, –used by planarians, –which senses light intensity and direction. © 2012 Pearson Education, Inc.

47. Figure 29.7A

48. 29.7 EVOLUTION CONNECTION: Several types of eyes have evolved independently among animals  Two major types of image-forming eyes have evolved in the invertebrates. 1. Compound eyes of insects –consist of up to several thousand light detectors called ommatidia, –function as acute motion detectors, and –usually provide excellent color vision. © 2012 Pearson Education, Inc.

49. Figure 29.7B

50. 29.7 EVOLUTION CONNECTION: Several types of eyes have evolved independently among animals 2.In single-lens eyes –light enters the front center of the eye through a small opening, the pupil, controlled by an iris, –passes through a single disklike lens, and –is focused onto the retina, which consists of many photoreceptor cells. –The center of focus is the fovea, where photoreceptor cells are highly concentrated. –Single-lens eyes –evolved independently in the vertebrates but –are similar in structure. © 2012 Pearson Education, Inc.

51. Figure 29.7C Sclera Ciliary body Ligament Cornea Iris Pupil Aqueous humor Lens Vitreous humor Blind spot Artery and vein Optic nerve Fovea (center of visual field) Retina Choroid

52. 29.8 Humans have single-lens eyes that focus by changing position or shape  The outer surface of the human eyeball is a tough, whitish layer of connective tissue called the sclera. –At the front of the eye, the sclera becomes the transparent cornea,which –lets light into the eye and –also helps focus light. –The sclera surrounds a pigmented layer called the choroid. The anterior choroid forms the iris, which gives the eye its color. © 2012 Pearson Education, Inc.

53. 29.8 Humans have single-lens eyes that focus by changing position or shape  The lens and ciliary body divide the eye into two fluid-filled chambers. 1.The large chamber behind the lens is filled with a jellylike vitreous humor. 2.The smaller chamber in front of the lens contains the thinner aqueous humor. –These humors –help maintain the shape of the eyeball and –circulate nutrients and oxygen to the lens, iris, and cornea. © 2012 Pearson Education, Inc.

54. 29.8 Humans have single-lens eyes that focus by changing position or shape  The conjunctiva –lines the inner surface of the eyelids and folds back over the white of the eye (but not the cornea). –Conjunctivitis is an inflammation of the conjuctiva by bacteria or a virus.  A gland above the eye secretes tears that –clean and –moisten the eye. © 2012 Pearson Education, Inc.

55. 29.8 Humans have single-lens eyes that focus by changing position or shape  The lens focuses light onto the retina by bending light rays. Focusing can occur in two ways. 1.In squids and fishes, the lens focuses by moving back and forth. 2.In mammals, the lens focuses by changing shape using –muscles attached to the choroid and –ligaments that suspend the lens. © 2012 Pearson Education, Inc.

56. Figure 29.8 Ciliary muscle contracted Ligaments slacken Light from a near object (diverging rays) Near vision (accommodation) Cornea Sclera Lens Ciliary muscle relaxed Ligaments pull on lens Light from a distant object (parallel rays) Distance vision Retina Choroid

57. 29.9 CONNECTION: Artificial lenses or surgery can correct focusing problems  Visual acuity is the ability of the eyes to distinguish fine detail. –Visual acuity is measured by reading standardized eye charts from a distance of 20 feet. –The ability to see normally at 20 feet is 20/20 vision. © 2012 Pearson Education, Inc.

58. 29.9 CONNECTION: Artificial lenses or surgery can correct focusing problems  Three vision problems are common. 1. Nearsightedness is the inability to focus on distant objects, usually caused by an eyeball that is too long. 2. Farsightedness is the inability to focus on close objects, usually caused by an eyeball that is too short. 3. Astigmatism is blurred vision caused by a misshapen lens or cornea.  Corrective lenses can bend light rays to compensate for each of these problems. © 2012 Pearson Education, Inc. Animation: Near and Distant Vision

59. Figure 29.9A Diverging corrective lens Focal point Shape of normal eyeball Focal point Lens Retina

60. Figure 29.9B Converging corrective lens Focal point Shape of normal eyeball Focal point

61. 29.10 The human retina contains two types of photoreceptors: rods and cones  The human retina contains two types of photoreceptors. 1. Rods –contain the visual pigment rhodopsin, which can absorb dim light, and –can detect shades of gray in dim light. 2. Cones –contain the visual pigment photopsin, which absorbs bright colored light, and –allow us to see color in bright light. © 2012 Pearson Education, Inc.

62. Figure 29.10A Rod Cone Membranous disks containing visual pigments Cell body Synaptic terminals

63. 29.10 The human retina contains two types of photoreceptors: rods and cones  When rhodopsin and photopsin absorb light, –they change chemically, and –the change alters the permeability of the cell’s membrane. –The resulting receptor potential triggers a change in the release of neurotransmitter from the synaptic terminals. –This release initiates a complex integration process in the retina. © 2012 Pearson Education, Inc.

64. Figure 29.10B Retina Optic nerve Retina NeuronsPhotoreceptors RodCone Optic nerve fibers To the brain

65. Figure 29.10B_1 Retina Neurons Photoreceptors RodCone Optic nerve fibers To the brain

66. TASTE AND SMELL © 2012 Pearson Education, Inc.

67. 29.11 Taste and odor receptors detect chemicals present in solution or air  Taste and smell d epend on chemoreceptors that detect specific chemicals in the environment.  Chemoreceptors –in taste buds detect molecules in solution and –lining the nasal cavity detect airborne molecules.  Taste and smell interact. Much of what we taste is really smell. © 2012 Pearson Education, Inc.

68.  Taste receptors –are located in taste buds on the tongue and –produce five taste sensations: 1.sweet, 2.salty, 3.sour, 4.bitter, and 5.umami (the savory flavor of meats and cheeses). 29.11 Taste and odor receptors detect chemicals present in solution or air © 2012 Pearson Education, Inc.

69. Figure 29.11 Brain Nasal cavity Odorous substance Mucus Cilia Sensory neuron (chemo- receptor) Epithelial cell Bone Olfactory bulb A c t i o n p o t e n t i a l s

70. 29.12 CONNECTION: “Supertasters” have a heightened sense of taste  About 25% of humans are “supertasters” with up to three times the sensitivity to bitter.  Supertasters are more likely to –avoid spinach, broccoli, cabbage, coffee, and alcoholic beverages and –be obese. © 2012 Pearson Education, Inc.

71. Figure 29.12

72. 29.13 Review: The central nervous system couples stimulus with response  The nervous system 1.receives sensory information, 2.integrates it, and 3.commands appropriate responses, either an action or no action. © 2012 Pearson Education, Inc.

73. You should now be able to 1.Describe the essential roles of sensory receptors. 2.Explain how electromagnetic receptors help the hammerhead shark perceive its world. 3.Define sensory transduction, receptor potential, and sensory adaptation, and provide examples of each. 4.Describe the five general categories of sensory receptors found in animals and provide examples of each. © 2012 Pearson Education, Inc.

74. 5.List the structures of the ear in the sequence in which they participate in hearing. 6.Explain how body position and movement are sensed in the inner ear. 7.Explain what causes motion sickness and what can be done to prevent it. 8.Compare the structures and functions of the eye cups of planarians, the compound eyes of insects and crustaceans, and the single-lens eyes of humans. You should now be able to © 2012 Pearson Education, Inc.

75. 9.Describe the parts of the human eye and their functions. 10.Explain the causes and symptoms of myopia, hyperopia, presbyopia, and astigmatism. 11.Compare the structures, functions, distributions, and densities of rods and cones. 12.Explain how odor and taste receptors function. 13.Describe the role of the central nervous system in sensory perception. You should now be able to © 2012 Pearson Education, Inc.

76. Figure 29.UN01 No signal Increasing signal

77. Figure 29.UN02 Outer earMiddle ear EardrumBones Inner ear Organ of Corti (inside the cochlea)

78. Figure 29.UN03 Ciliary muscle contracted Ligaments slacken Light from a near object (diverging rays) Cornea Sclera Lens Retina Choroid

79. Figure 29.UN04 Sensory receptors electromagnetic receptors pain and thermoreceptors (b)(a) are grouped into several types involved in involved in many types found in sensitive to (c) human skin taste and smell touch, hearing, balance many are (d) most common are (e)