1. 12 Unit 1 Chapter 12

2. 12 Unit 1 Smell (olfaction) taste (gustation) vision balance hearing

3. 12 Unit 1 Temperature Touch Pressure Vibration Proprioception Pain Internal organ conditions

4. 12 Unit 1 Conscious or subconscious awareness of change in external or internal environment Requires: 1.Stimulus 2.Sensory receptor 3.Neural pathway 4.Brain region for integration

5. 12 Unit 1 Perception- conscious awareness Cerebral cortex function Adaptation- decreased receptor response with prolonged stimulation  decreased perception Adaptation speed varies with receptor

6. 12 Unit 1 Free nerve endings- pain, thermal, tickle, itch & some touch receptors Encapsulated nerve endings Touch pressure & vibration Specialized cells: e.g. hair cells in inner ear

7. 12 Unit 1 Mechanoreceptors- cell deformation, stretching or bending Thermoreceptors- temperature Nociceptors – pain Photoreceptors- light Chemoreceptors- chemicals Taste, smell, body fluid content

8. 12 Unit 1 Receptors- distributed unevenly In skin, mucous membranes, muscles, tendons,& joints Dense receptors concentration in fingertips, lips & tip of tongue

9. 12 Unit 1 Touch, pressure, vibration, itch & tickle Itch & tickle – free nerve endings encapsulated mechanoreceptors

10. 12 Unit 1 Rapidly adapting receptors: Meisner corpuscles Hair root plexuses Slowly adapting receptors: Type I mechanoreceptors= Merkel discs- surface receptors- stratum basale Type II mechanoreceptors= Ruffini corpuscles- deep in dermis & tendons

11. 12 Unit 1 Sensation over large area Lamellated or Pacinian corpuscles Rapid adapting & widely distributed Vibration = rapidly repetitive stimuli Corpuscles of touch- low frequency Lamellated corpuscles- higher frequency

12. Figure 12.1

13. 12 Unit 1 Itch- chemical stimulation of free nerve endings Bradykinin from inflammation response Tickle- from free nerve endings & lamellated corpuscles Requires someone else- blocked by signals from cerebellum

14. 12 Unit 1 Two kinds of thermoreceptors- Between 10 o & 40 o C - cold Located in epidermis Between 32 o & 48 o C – warm located in dermis Outside these ranges – nociceptors Both adapt rapidly but continue slow signals during prolonged stimulus

15. 12 Unit 1 Nociceptors- free nerve endings Found in every tissue but brain Very little adaptation Fast pain= acute, sharp pain (0.1 sec) not felt in deep tissues and well localized Slow pain- slow starting & increases Chronic, burning, aching or throbbing sensation Visceral pain location displaced to surface = referred pain

16. Figure 12.2

17. 12 Unit 1 Head and limb position & motion Located in muscles (muscle spindles), tendons (tendon organs), in & around synovial joints (joint kinesthetic receptors) Kinesthesia= perception of movements Inner ear (hair ceils)- head position Tracts to primary sensory area of cerebral cortex & cerebellum Slow & slight adaptation

18. Figure 10.13

19. 12 Unit 1 In upper surface of superior concha, below cribiform plate Olfactory receptors- first order neurons of olfactory pathway Connect to olfactory bulb Have olfactory hairs containing chemoreceptors Supporting cells- epithelial cells – support & electrical insulation Basal cells- stem cells for receptors

20. Figure 12.3a

21. 12 Unit 1 Genetic evidence- 100’s of primary odors Binding of chemical stimulates nerve Recognition of 10,000 odors from combination of primary receptor input Rapid adaptation by ~50% in 1 sec.

22. 12 Unit 1 Olfactory receptor’s axons = Olfactory nerves through cribiform plate  olfactory bulbs Olfactory tract To primary olfactory area of temporal lobe And limbic system - emotional response to smells, e.g. nausea or arousal

23. Figure 12.3 b

24. 12 Unit 1 5 primary tastes: salt, sweet, sour, bitter & umami Perception of what we call taste includes olfactory input Receptors in taste buds (~10,000) Located on tongue & pharynx & epiglottis In structures called papillae Vallate (back), fungiform (all over) filiform- touch receptors only

25. Figure 12.4a

26. Figure 12.4b

27. 12 Unit 1 Epithelial cells: Supporting cells surrounding Gustatory receptor cells Gustatory hair projects from receptor through taste pore Basal cells= stem cells Produce supporting cells that develop into receptor cells (10 day life span)

28. Figure 12.4c

29. 12 Unit 1 Tastant- dissolved in saliva Receptors respond to more than one tastant Release neural transmitter to primary gustatory neuron Tastes arise from mix of input form various areas

30. 12 Unit 1 Facial & glossopharyngeal-tongue vagus- pharynx & epiglottis to medulla oblongata  thalamus  primary gustatory area- consciousness Also medulla  limbic system

31. 12 Unit 1 Accessory structures- eye brows, eyelashes- protection eye lids- protection & lubrication (blinking) extrinsic muscles- moving eyeball Superior Rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, inferior oblique Lacrimal apparatus- Gland  lacrimal duct  surface of upper eyelid  lacrimal canal & nasolacrimal duct  nasal cavity

32. Figure 12.5

33. 12 Unit 1 Fibrous tunic – Anterior clear cornea Sclera- white of eye Vascular tunic- contains: Choroid- Lines most of internal surface carries blood vessels Ciliary body- focuses the lens and secretes aqueous humor Iris- o pens & closes pupil- contains pigment of eye color. Pupil = hole for light passage Adjusted by iris to control amount of light through the lens

34. Figure 12.6

35. Figure 12.7

36. 12 Unit 1 Retina- two layers neural layer- outgrowth of brain Photoreceptor layer Bipolar cell layer Ganglion cell layer pigmented layer- helps absorb stray light between choroid & neural layer

37. 12 Unit 1 Rods very sensitive, black & white Cones- color sensitive, 3 types-blue, green & red Color vision results from combined input Cones mostly in central fovea in center of macula lutea Area of highest visual resolution Information  bipolar layer  ganglion cells  axons = optic nerve

38. Figure 12.8

39. 12 Unit 1 Two cavities- Anterior cavity & Vitreous Chamber divided by lens Anterior filled with aqueous humor Drains into canal of schlemm.- replaced ~90 min. Maintains eye shape & nourishes lens & cornea Responsible for intraocular pressure Vitreous chamber- filled with vitreous body Gel-like - holds retina against choroid

40. 12 Unit 1 Light rays bend on passing from medium of one density to another of different density = refraction 75% occurs at cornea Lens- focuses light on the retina Image is inverted but brain adjusts & interprets distance and size

41. Figure 12.9a

42. Figure 12.9b

43. Figure 12.9c

44. 12 Unit 1 Lens adjusts for distance to keep image focused on retina With distant objects ciliary muscle is relaxed Contracts as the object becomes closer Myopia= can’t accommodate distant objects- Eyeball is too long Hyperopia = can’t accommodate far objects- Eyeball is too short Astigmatism= irregular curvature of cornea or lens

45. Figure 12.10

46. 12 Unit 1 Constriction of pupil- autonomic reflex to center light on lens Convergence- eyes rotate toward midline as object nears it is necessary to maintain focus on single object for binocular vision Photoreceptors: light  neural signal light is absorbed by a photopigment (rhodpsin) which splits into opsin & retinal

47. 12 Unit 1 Optic nerve through optic chiasm About 1/2 cross over into optic tract  hypothalamus  occipital lobes Right brain sees left side of object Left brain sees right side of object

48. Figure 12.11

49. 12 Unit 1 Outer ear- Auricle, external auditory canal & tympanic membrane (ear drum) Canal contains hairs & ceruminous glands Middle ear- auditory tube (eustachian tube) & ossicles Ossicles = Malleus, incus, & stapes-attached to oval window Inner ear- Bony labyrinth & membranous labyrinth filled with endolymph Cochlea- sense organ of hearing, vestibule & semicircular canals- organs of balance

50. Figure 12.12

51. 12 Unit 1 Vestibule includes Two sacs: utricle & saccule Semicircular canals- orthogonal End in swelling called ampulla Semiscisular ducts connect to utricle Cochlea- 3 channels Cochlear duct- membranous & has endolymph Above: Scala vestibuli - ends at oval window Below: Scala tympani - ends at round window In cochlear duct- spiral organ = organ of Corti

52. 12 Unit 1 Sits on basilar membrane between scala tympani & cochlear duct Contains supporting cells & hair cells Hair cells =receptors for auditory sensations Synapse with sensory & motor neurons in cochlear branch of vestibulocochlear nerve

53. Figure 12.13a

54. Figure 12.13b

55. 12 Unit 1 Waves in air  auditory canal  tympanic membrane & ossicle movement  pressure waves in perilymph  scala vestibuli  scala tympani  pressure waves in endolymph  basilar membrane bending hair cells  neural transmitter to sensory neurons Pitch (wavelength)  location in cochlea Volume (loudness)  intensity of waves

56. Figure 12.14

57. 12 Unit 1 Cochlear neurons end on same side in medulla Through midbrain to thalamus  Auditory Cortex on Temporal lobe Receives input from both ears

58. 12 Unit 1 Static equilibrium- position relative to gravity Dynamic equilibrium- position in response to head movement

59. 12 Unit 1 Sensed in maculae of Utricle & Saccule gravity pulls on otoliths in otolithic membrane bends hair cells Triggers nerve impulses in vestibular branch of vestibulochochlear nerve

60. Figure 12.15a

61. Figure 12.15b

62. 12 Unit 1 Semicircular canals- at right angles to each other Cristae in each ampulla have hair cells and supporting cells When head turns hair cells move Endolymph lags and bends hair cells Bend triggers nerve impulse in vestibular branch

63. Figure 12.16a

64. Figure 12.16b

65. 12 Unit 1 Axons from vestibular branch  medulla or cerebellum Medulla  motor for eye & head & neck  spinal cord tracts for adjusting muscle tone & postural muscles