1. BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 29 The Senses

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The brown bear is able to capture a fast and agile salmon Sensory structures of both the bear and salmon gather the information that guides the behaviors involved in this encounter An Animal's Senses Guide Its Movements

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Nostrils on each side of the head of the salmon allow water to flow into one and out the other Sensory cells in the nostrils detect specific chemicals in the water –These cells aid the salmon in its homing ability

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Salmon have a lateral line system, seen here as a blue line along the sides of the fish –This enables the salmon to sense the direction and velocity of water currents and thus distinguish which direction is upstream –Unfortunately for the salmon, it cannot perceive a bear's paw descending from above

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensation –Awareness of sensory stimuli Perception –Brain’s full integration of sensory data 29.1 Sensory inputs become sensations and perceptions in the brain Figure 29.1

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sensory transduction –A sensory cell converts a stimulus into an electrical signal called a receptor potential –Occurs as a change in the membrane potential of a receptor cell 29.2 Sensory receptor cells convert stimuli into electrical energy SENSORY RECEPTION

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 29.2A Taste bud anatomy 1 2 Sugar binding Tongue Taste pore Taste bud Sugar molecule Sensory receptor cells Sensory neuron Receptor cell membrane Sugar molecule Ion channels Ion 3 Receptor potential 4 Synapse Sensory receptor cell Neuro- transmitter molecules Sensory neuron Action potential 5 Action potentials No sugarSugar present mV

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Action potentials representing the stimuli are transmitted to the CNS via sensory neurons The brain distinguishes different types of stimuli –These synapse with different interneurons in the brain

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The strength of a stimulus alters the rate of action potential transmission –This communicates information about the intensity of a sensation –In sensory adaptation, sensory neurons become less sensitive when stimulated repeatedly

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 29.2B Sugar receptor BRAIN Interneurons Salt receptor Sensory neurons TASTE BUD No salt Increasing sweetnessIncreasing saltiness No sugar

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pain receptors –Sense dangerous stimuli Thermoreceptors –Detect heat or cold Mechanoreceptors –Respond to mechanical energy (touch, pressure, and sound) 29.3 Specialized sensory receptors detect five categories of stimuli

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 29.3A HeatLight touch PainCold(Hair)Light touch Epidermis Dermis NerveTouchStrong pressure

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Stretch receptors and hair cells are two types of mechanoreceptors Figure 29.3B “Hairs” of receptor cell Neurotransmitter at synapse Sensory neuron Action potentials More neurotransmitter (1) Receptor cell at rest(2) Fluid moving in one direction Less neurotransmitter (3) Fluid moving in other direction

14. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Chemoreceptors –Respond to chemicals in the body fluids or external environment –A male silkworm moth has chemoreceptors on his antennae that can detect the sex attractant produced by the female silkworm moth Figure 29.3C

15. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Electromagnetic receptors –Respond to electricity, magnetism, and light Photoreceptors sense light –They are the most common electromagnetic receptors Figure 29.3D Eye Infrared receptor

16. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Eye cup –Simplest type of photoreceptor –Senses intensity and direction of light –Found in flatworms 29.4 Three different types of eyes have evolved among invertebrates VISION Figure 29.4A Light

17. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Compound eye –Contains thousands of ommatidia working together to produce a visual image –Acute motion detector –Provides excellent color vision –Found in crabs, crayfish, and nearly all insects Figure 29.4B

18. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Single-lens eye –Works on a principle similar to that of a camera –Found in vertebrates and some invertebrates, such as squids Figure 29.4C

19. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 29.5 Vertebrates have single-lens eyes Figure 29.5 Sclera Muscle Ligament Iris Pupil Cornea Aqueous humor Lens Vitreous humor Choroid Retina Fovea (center of visual field) Optic nerve Artery and vein Blind spot

20. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Human eye –Cornea and lens focus light on photoreceptor cells in the retina –Photoreceptors are most concentrated in the fovea –Having two eyes with overlapping fields of view compensates for the blind spot –The blind spot is where the optic nerve passes through the retina

21. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Focusing can occur in two ways Moving the lens closer to or farther away from an object is one focusing method –It is similar to focusing with a magnifying glass –This occurs in squid and some fishes 29.6 To focus, a lens changes position or shape

22. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Accommodation, or changing the shape of the lens, occurs in the mammalian eye –Thick and round for near vision –Thin and flat for distance vision Figure 29.6 Muscle contracted Ligaments Light from a near object Lens Choroid Retina NEAR VISION (ACCOMMODATION) DISTANCE VISION Muscle relaxed Light from a distant object

23. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Corrective lenses bend light rays to compensate for focusing problems There are three common vision problems –Astigmatism is a condition involving a distortion of the lens or cornea 29.7 Connection: Artificial lenses or surgery can correct focusing problems

24. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In nearsightedness (myopia), the focal point is located in front of the retina Figure 29.7A Lens Retina Shape of normal eyeball Focal point Corrective lens Focal point

25. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In farsightedness (hyperopia), the focal point is located behind the retina Figure 29.7B Shape of normal eyeball Focal point Corrective lens Focal point

26. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Human photoreceptor cells are named for their shapes –Rods –Cones 29.8 Our photoreceptor cells are rods and cones Figure 29.8A Cell body Synaptic knobs Membranous discs containing visual pigments ROD CONE

27. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Rods –Function in dim light –Contain a visual pigment called rhodopsin –There are 125 million in the human retina

28. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cones –Stimulated by bright light –Enable color vision –Do not function in night vision –There are 6 million in the human retina Cones contain visual pigments called photopsins –There are three types of cones— blue, green, and red— named for the color absorbed by their photopsin

29. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 29.8B Retina Optic nerve Fovea Optic nerve fibers Retina Photoreceptors NeuronsConeRod

30. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The basic function of the ear is hearing –The outer ear channels sound waves to the eardrum 29.9 The ear converts air pressure waves into action potentials that are perceived as sound HEARING AND BALANCE Figure 29.9A OUTER EAR MIDDLE EAR INNER EAR Pinna Auditory canal Eustachian tube

31. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –The eardrum passes vibrations to the chain of bones in the middle ear Figure 29.9B Stirrup Anvil Hammer Skull bones Semicircular canals (function in balance) Auditory nerve, to brain Cochlea Eardrum Oval window (behind stirrup) Eustachian tube

32. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –The bones transmit vibrations to fluid in the cochlea, which houses the organ of Corti –Vibrations in cochlear fluid move hair cells (mechanoreceptors) against the overlying membrane –Bending hair cells trigger nerve signals to the brain via the auditory nerve

33. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Middle canal Bone Cross section through cochlea ORGAN OF CORTI Lower canal Upper canal Auditory nerve Hair cells Overlying membrane Sensory neurons Basilar membrane To auditory nerve Figure 29.9C

34. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Louder sounds generate higher amplitude pressure waves –These waves result in the vigorous vibration of cochlear fluids –There is then a more pronounced bending of hair cells –Thus more action potentials are generated

35. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 29.9D OUTER EARMIDDLE EARINNER EAR Pinna Auditory canal Ear- drum Hammer, anvil, stirrup Oval window Cochlear canal Upper and middleLower Time Organ of Corti stimulated Amplification in middle ear One vibration Amplitude Pressure

36. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pitch depends on the frequency of sound waves –High sounds generate high frequency sound waves –Low sounds generate low frequency sound waves –Sounds of different pitches stimulate hair cells in different parts of the organ of Corti

37. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Organs of balance are located in the inner ear –Semicircular canals –Utricle –Saccule Detection of body position and movement are determined by stimulation of hair cells in the semicircular canals, utricle, and saccule 29.10 The inner ear houses our organs of balance

38. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Equilibrium structures in the inner ear Figure 29.10 Semicircular canals Nerve Cochlea Utricle Saccule Flow of fluid Cupula Flow of fluid Cupula Hairs Hair cell Nerve fibers Direction of body movement

39. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Motion sickness is a result of the brain receiving signals from equilibrium receptors in the inner ear that conflict with visual signals from the eyes 29.11 Connection: What causes motion sickness?

40. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Smell and taste depend on chemoreceptors sending nerve signals to the brain –Specific molecules binding to chemoreceptors determine signals 29.12 Odor and taste receptors detect categories of chemicals TASTE AND SMELL

41. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Olfactory (smell) receptors are sensory neurons that line the upper part of the nasal cavity Figure 29.12A BRAIN NASAL CAVITY Action potentials Bone Chemo- receptor cell Cilia Epithelial cell MUCUS

42. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Taste receptors are sensory neurons located in the back of the throat and on the tongue (taste buds) There are several types of taste receptors –Sweet, sour, salty, bitter, umami

43. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Insects have taste receptors located in sensory hairs on their feet –They can taste food by simply stepping on it Figure 29.12B To brain Chemo- receptor cells Sensory hair Pore at tip

44. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Receptor potential is generated when specific chemical molecules bind with olfactory or taste receptors Receptor potential alters the rate of action potentials passing into the brain The various odors and tastes we perceive result from the integration of input from a combination of receptors

45. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Coupling of stimuli to response by the nervous system –Receptor cells receive stimulus –Sensory neurons send information to the CNS –The CNS integrates information from receptor cells –The CNS sends commands to effector cells via motor neurons –Response is carried out 29.13 Review: The central nervous system couples stimulus with response

46. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 29.13 Motor neuron CNS StimuliReceptors Sensory neurons Integration Effector Response