1. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 41 Sensory Reception

2. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Sensory receptors Neuron endings Specialized receptor cells in close contact with neurons Sense organs Sensory receptors Accessory cells

3. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Mechanoreceptors Transduce mechanical energy Animal functions –Feeling –Hearing –Maintaining balance

4. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Chemoreceptors Transduce certain kinds of chemical compounds Allow taste and olfaction

5. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Thermoreceptors Transduce thermal energy In endothermic animals, thermoreceptors provide cues about body temperature Some invertebrates use thermoreceptors to locate endothermic prey

6. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Thermoreception

7. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Electroreceptors Used by predatory fishes to detect prey Respond to electrical stimuli

8. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Photoreceptors Transduce light energy Serve as the sensory receptors in eyespots and eyes

9. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Receptor cells Absorb energy Transduce it into electrical energy Produce receptor potentials –Depolarizations or hyperpolarizations of the membrane –Graded responses

10. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Sensation process Sensory receptors transmit coded signals Brain interprets signals

11. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Sensory adaptation Decrease in frequency of action potentials in a sensory neuron Occurs even when the stimulus is maintained Decreases response to the stimulus

12. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Mechanoreceptors Touch Pressure Gravity Stretch Movement

13. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Mechanoreceptors are activated when they change shape as a result of being mechanically pushed or pulled

14. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Tactile receptors Found in the skin Respond to mechanical displacement of hairs Respond to displacement of the receptor cells

15. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Nociceptors Pain receptors Free nerve endings of certain sensory neurons –Strong tactile stimuli –Temperature extremes –Certain chemicals

16. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Proprioceptors Enable the animal to perceive orientation of the body and positions of its parts –Muscle spindles –Golgi tendon organs –Joint receptors

17. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Proprioceptors

18. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Statocysts Gravity receptors Found in many invertebrates

19. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Statocysts

20. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vertebrate hair cells Detect movement Found in –Lateral line of fishes –Vestibular apparatus –Semicircular canals –Cochlea

21. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vertebrate hair cells Single kinocilium –True cilium Stereocilia –Microvilli –Contain actin filaments

22. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Lateral line organs Supplement vision in fish and some amphibians Inform the animal of moving objects or objects in its path

23. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Lateral line organ

24. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vertebrate inner ear Labyrinth of fluid-filled chambers Canals that help maintain equilibrium

25. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vestibular apparatus Upper part of the labyrinth Saccule Utricle Semicircular canals

26. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human ear

27. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Otoliths Stimulate hair cells that send signals to the brain Enable the animal to perceive the direction of gravity

28. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Saccule and utricle Change position when the head is tilted Change position when the body is moving in a straight line Semicircular canals Inform the brain about turning movements

29. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Inner ear

30. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Cristae Clumps of hair cells Located within each bulblike enlargement Stimulated by movements of the endolymph –Fluid that fills each canal

31. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Organ of Corti Found within the cochlea Contains auditory receptors

32. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Path taken by sound waves Sound waves pass through the external auditory canal Tympanic membrane (eardrum) vibrates Ear bones transmit and amplify the vibrations through the middle ear

33. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vibrations pass through the oval window to fluid within the vestibular duct Pressure waves press on the membranes that separate the three ducts of the cochlea Bulging of the round window serves as a pressure escape valve

34. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Pressure waves cause movements of the basilar membrane Movements stimulate the hair cells of the organ of Corti by rubbing them against the overlying tectorial membrane

35. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Neural impulses Initiated in the dendrites of neurons that lie at the base of each hair cell Transmitted by the cochlear nerve to the brain

36. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Chemoreceptors for taste and smell Taste receptor cells –Specialized epithelial cells in taste buds Olfactory epithelium –Specialized olfactory cells –Axons that extend to the brain

37. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Olfactory epithelium

38. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Taste and smell process Molecule binds with a receptor –Taste receptor cell –Olfactory receptor cell Signal transduction process involving a G protein is initiated

39. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Eyespots (ocelli) Found in cnidarians and flatworms Detect light Do not form images

40. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Eyespots

41. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Compound eye of insects and crustaceans Visual units called ommatidia –Collectively produce a mosaic image –Transparent lens –Crystalline cone –Focuses light onto retinular receptor cells

42. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human eye structures and functions Light enters through the cornea Light is focused by the lens Image is produced on the retina Iris regulates the amount of light

43. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human eye

44. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Photoreceptor cells in the retina Rods –Function in dim light –Black and white images Cones –Function in bright light –Color vision

45. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Bipolar cells Send signals to ganglion cells

46. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Lateral interneurons Integrate information Horizontal cells –Receive signals from the rods and cones –Send signals to bipolar cells

47. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Amacrine cells –Receive signals from bipolar cells –Send signals back to bipolar cells and to ganglion cells

48. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Neural pathway in the retina

49. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human vision process Light strikes the photopigment rhodopsin in the rod cells Retinal portion changes shape Initiates a signal transduction process that involves transducin

50. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception G protein activates an esterase that hydrolyzes cGMP Reduces cGMP concentration Ion channels close Membrane becomes hyperpolarized

51. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Rod cells release less glutamate Fewer signals are transmitted Bipolar cells become depolarized Bipolar cells release neurotransmitter that stimulates ganglion cells