1. Sensory Biol. 211 Anatomy & Physiology 1 Tony Serino, Ph.D. Biology Department Misericordia University

2. Sensation –state of awareness of external and internal conditions of the body Four conditions for sensation: –1. Adequate stimulus –2. Adequate receptor (transducer) –3. Conduction –4. Translation (interpretation)

3. Brain’s Assumption in Translating Assumption: Source of light is from above

4. Reversing X pattern; notice shading.

5. How many triangles? Assumption: Straight lines should connect.

6. Which dark line is larger? Assumption: perspective

7. Characteristics of Sensation Modality –ability to interpret nerve impulses differently Projection –referral of sensation to point of origin Adaptation –decrease in sensitivity of receptors to continued stimulation –Phasic (fast) –Tonic (slow) –Some receptors never adapt (pain, cold, etc.) Afterimage –persistence of sensation after stimulus ceases

8. Classification of Receptors Type of Sensory Information Relayed –Exteroreceptors, Enteroreceptors, Proprioceptors Type of Stimulus Transduced –Mechanoreceptors, Thermoreceptors, Chemoreceptors, and Nociceptors Complexity of Receptor –Simple structure (usually single cell) – most general senses –Complex structure (many cells) –special senses

9. Receptor Physiology Stimulation of a receptor leads to the generation of a receptor (generator) potential in its membrane. These are usually excitatory, and are similar to the EPSPs found in neurons If the receptor potential reaches the threshold potential for the sensory neuron; it fires an AP into the CNS Strength of the stimulus is therefore encoded by the number of AP generated Sensations may be sharpened through Lateral Inhibition

10. Lateral Inhibition - -

11. General Senses Cutaneous –skin receptors Proprioception –sense of body position Nociception –pain perception (chemoreceptors that perceive locally secreted warning hormones (prostaglandins))

12. Distribution of Cutaneous Receptors

13. Sensitivity of Skin due to Receptive Fields

14. Cutaneous Receptors

16. Proprioceptors

17. Muscle sensors Muscle spindles (Intrafusal fibers: -senses degree of length of muscle fibers and the rate of change in length Golgi Tendon organs –sense tension within tendon

18. Relationship of Stretch to AP

19. Referred Pain Illustrates projection.

20. General Pathway of Perception

21. Taste (Gustatory) Sense

22. Taste Bud

24. Olfaction (smell) Sense

25. Olfactory Epithelium

26. Olfaction Signal Transduction

27. Vision

28. Accessory Structures of the Eye

29. Lacrimal Apparatus

31. Extrinsic Ocular Muscles

32. Action and Innervation of Ocular Muscles Which cranial nerve is injured?

33. Eye Anatomy

34. (Canal of Schlemm) Aqueous Humor Flow Glaucoma results from inadequate drainage of Aqueous Humor leading to increase pressure in the eye.

35. Iris controls amount of light entering the eye.

36. Distant Vision

37. Near Vision (Accomodation)

38. Near and Far-sightedness

39. Astigmatism and Presbyopia Astigmatism –results from imperfections in the resolving structures in the eye (lens and/or cornea) Presbyopia is the loss of near vision with age; resulting from a decrease in elasticity of the lens.

40. Retina Cellular Arrangement

41. Special Areas of Retina

42. Blind Spot Optic N. Optic Disc (blind spot)

43. Photoreceptors: Cones and Rods

44. Three Population of Cones

45. Rod’s and Cone’s Photopigments

46. Rhodopsin

48. Light Signal Transduction

49. Visual Processing

50. Sound

51. Frequency vs. Loudness Frequency measured in hertz (Hz) Loudness measured in decibels (dB)

52. Anatomy of the Ear

53. Middle and Inner Ear

54. Ossicles Amplify Sound

55. Loud Sound Protection

56. Middle Ear Ossicles

57. Cochlea and Cochlear Duct

58. Organ of Corti

59. Hair Cells in Cochlear Duct

60. Frequency Perception Different frequency (pitch) of sound stimulates different areas of cochlear duct The overall area stimulated relates to the sound intensity

61. Vestibular Apparatus

62. Macula of Utricle and Saccule

63. Macula Otoconia (otoliths)

64. Hair Cell of Macula

65. AP Generation in Macula

66. Ampulla Anatomy