1. PowerLecture: Chapter 35 Sensory Perception

2. Sensory Receptors Convert energy of a stimulus into action potentials MechanoreceptorsThermoreceptors Pain receptors ChemoreceptorsOsmoreceptorsPhotoreceptors

4. Assessing a Stimulus  Action potentials don’t vary in amplitude  Brain tells nature of stimulus by:  1) Particular pathway that carries the signal  2) Frequency of action potentials (how quickly is signal repeated)  3) Number of receptors signalling

5. Recordings of Action Potentials

6. Action Potential Signals  Are sent down specialized cells called neurons

7. Types of Neurons  Sensory neurons (receptors): receive stimulus  Interneurons (in brain and spinal cord) integrate information from receptors  Motor neurons : signal effectors (muscle) to respond

8. Sensory Pathways

9. Sensory Adaptation A decrease in response to a stimulus is being maintained at constant strength for long periods of time

10. Taste Taste  Chemoreceptors  Five primary sensations: sweet, sour, salty, bitter, and umami sweet, sour, salty, bitter, and umami Figure 35.8 Page 604

11. Smell  Olfactory receptors  Receptor axons lead to olfactory lobe  Binding molecules triggers action potential olfactory bulb receptor cell Figure 35.7 Page 604

12. Balance and Equilibrium Balance and Equilibrium  In humans, organs of equilibrium are located in the inner ear  Vestibular apparatus vestibular apparatus saccule utricle semicircular canals Figure 35.9b Page 605

13.  Moving in response to gravity, otoliths bend projections of hair cells and stimulate the endings of sensory neurons Acceleration-Deceleration hair cellotolithsmembrane vestibular nerve

14. Dynamic Equilibrium  Rotating head movements cause pressure waves that bend a gelatinous cupula and stimulate hair cells inside it cupula

15. Dynamic equilbirum Dynamic Equilibrium

16. Properties of Sound Properties of Sound  Ear detects pressure waves  Amplitude of waves corresponds to perceived loudness  Frequency of waves (number per second) corresponds to perceived pitch

17. Anatomy of Human Ear cochlea auditory nerve eardrum auditory canal hammer anvil stirrup Fig. 35.11a Page 614

18. Ear structure and function Anatomy of Human Ear

19. Sound Reception  Sound waves make the eardrum vibrate  Vibrations are transmitted to the bones of the middle ear  The stirrup transmits force to the oval window of the fluid-filled cochlea

20. Sound Reception  Movement of oval window causes waves in the fluid inside cochlear ducts Figure 35.11c Page 606 eardrumround window oval window (behind stirrup) scala vestibuli scala tympani

21. scala vestibuli cochlear duct organ of Corti scala tympani sensory neurons (to the auditory nerve) Fig. 35-11d, p.607

22. Sound Reception hair cells in organ of Corti tectorial membrane lumen of cochlear duct basilar membrane lumen of scala tympani to auditory nerve Figure 35.11e Page 607

23. Fig. 35-12a, p.607

24. Vision Vision  Sensitivity to light does not equal vision  Vision requires two components Eyes Eyes Capacity for image formation in the brain Capacity for image formation in the brain

25. Invertebrate Eyes Limpet ocellus sensory neuron epidermis cuticle lens Land snail eye Compound eye of a deerfly ommatidium Figures 35.13 & 35.14 Pages 608 & 609

26. Fig. 35-13d, p.608 Invertebrate Eyes

27. Fig. 35-1,e, p.608 Invertebrate Eyes

28. Fig. 35-15, p.609 vitreous body cornearetinaoptic tract lens

29. Human Eye sclera choroid iris lens pupil cornea aqueous humor ciliary muscle vitreous body retina fovea optic disk part of optic nerve Figure 35.17 Page 610

30. Eye structure Human Eye

31. Pattern of Stimulation  Light rays pass through lens and converge on retina at back of eye  The image that forms on the retina is upside down and reversed right to left compared with the stimulus  Brain accounts for this during processing

32. Pattern of Stimulation Figure 35.18a Page 611

33. a Light rays from an object converge on the retina, form an inverted, reversed image. b When a ciliary muscle contracts, the lens bulges, bending the light rays from a close object so that they become focused on the retina. c When the muscle relaxes, the lens flattens, focusing light rays from a distant object on the retina. muscle contracted slack fibers muscle relaxed close object distant object taut fibers Fig. 35-18, p.611

34. Visual Accommodation  Adjustments of the lens  Ciliary muscle encircles lens  When this muscle relaxes, lens flattens, moves focal point farther back  When it contracts, lens bulges, moves focal point toward front of eye

35. Organization of Retina  Photoreceptors lie at the back of the retina, in front of a pigmented epithelium  For light to reach the photoreceptors, it must pass layers of neurons involved in visual processing

36. stacked, pigmented membrane cone cell rod cell Fig. 35-19, p.612

37. Organization of Retina  Signals from photoreceptors are passed to bipolar sensory neurons, then to ganglion cells Figure 35.20 Page 612

39. Organization of cells in the retina Organization of Retina

40. The Photoreceptors  Rods Contain the pigment rhodopsin Contain the pigment rhodopsin Detect very dim light, changes in light intensity Detect very dim light, changes in light intensity  Cones Three kinds; detect red, blue, or green Three kinds; detect red, blue, or green Provide color sense and daytime vision Provide color sense and daytime vision

41. fovea Fig. 35-22, p.613 start of an optic nerve in back of the eyeball Fovea and Optic Nerve

42. Retina to Brain retina optic nerve lateral geniculate nucleus visual cortex Figure 35.23 Page 613

43. Pathway to visual cortex Visual Cortex

44. distant object (focal point) Fig. 35-24a, p.614 Nearsighted Vs Farsighted