1. Somatic and Special Senses
Chapter 10

2. Introduction
Sensory Receptors- detect environmental changes and trigger nerve impulses that travel on sensory pathways into the CNS for processing and interpretation

3. 2 large types of sensory receptors
1. Somatic senses: touch, pressure, temperature, and pain
2. Special senses: smell, taste, hearing, equilibrium, and vision

4. Receptors and Sensations
Receptors are distinct to a type of environmental change
This selective response distinguishes the senses
5 kinds

5. 1. Chemoreceptors
Stimulated by changes in the chemical concentration of substances

6. 2. Pain Receptors Stimulated by tissue damage

7. 3. Thermoreceptors Stimulated by changes in temperature

8. 4. Mechanoreceptors Stimulated by changes in pressure or movement

9. 5. Photoreceptors Stimulated by light energy

10. Sensation
Sensation-a feeling that occurs when the brain interprets sensory impulses
Impulse is read depending on what area of the brain receives it
One area may be sound and one area may be touch

12. Projection
Projection-process where the cerebral cortex causes a feeling to stem from a source
It allows a person to pinpoint the region of stimulation (eyes & ears)

13. Sensory Adaptation
Sensory adaptation-sensory receptors stop sending signals when they are repeatedly stimulated
Can only be triggered if stimulus strength changes again
Think smell (phasic)

15. Somatic Senses 1. Sensory Nerve Fibers Common in epithelial tissues
Are associated with touch and pressure

16. 2. Meissner’s Corpuscles
Small masses of connective tissue
Located in hairless portions of the skin (lips, fingertips, palms, soles, nipples, external genitalia)
Interpret light touch

17. 3. Parcinian Corpuslces Large structures of connective tissue
Located in deep tissue layers like ligaments and tendons
Respond to heavy pressure

18. Temperature Senses
1. Warm Receptors - nerve endings that respond to warmer temperatures (sensitive above 77°, unresponsive above 113°F)
2. Cold Receptors - nerve endings that respond to colder temperatures (sensitive between 50°F and 68°F)

20. Sense of Pain
These protect the body because tissue damage stimulates them
Usually unpleasant and signals the person to remove the stimulation
Pain is persistent and doesn’t go away
Four types

21. 1. Visceral Pain
Occurs in visceral tissues such as heart, lungs, intestine

22. 2. Referred Pain
Feels as though it is coming from a different part (heart pain may be felt as pain in arm or shoulder)
Caused from Nerves passing through the same area

23. 3. Acute Pain
Originates from skin, usually stops when stimulus stops (needle prick)

24. 4. Chronic Pain Dull aching sensations

25. Regulation of pain
Pain is interpreted by the Cerebral Cortex in the brain.
Three types of neuropeptides that inhibit pain: serotonin, enkephalins, endorphins.
Natural brain chemicals can be mimicked by drugs such as morphine.

26. Morphine

27. Special Senses Smell: olfactory organs Taste: taste buds
Hearing equilibrium: Ears
Sight: Eyes

28. http://www. exploringnature

29. Sense of Smell
The sense of smell is associated with complex sensory structures in the upper region of the nasal cavity

30. Olfactory Receptors
Chemoreceptors that are stimulated by chemicals that are dissolved in liquid
Aid in food selection because smell and taste are closely related

31. Olfactory Organs
Contain the olfactory receptors which are masses that cover the upper parts of the nasal cavity

32. Olfactory Receptor Cells
Bipolar neurons surrounded by epithelial cells
Covered in cilia which have receptor proteins that the odor chemicals bind to

33. Olfactory Bulbs
Receive the nerve impulses from the receptor cells (located in the brain)

34. Olfactory Tracts
Located inside the olfactory bulbs and interpret the nerve impulses
Smell Video

35. 10.6 Sense of Taste ( )

36. The special organs of taste; papillae

37. Gustatory cells; 50 to 150 receptor cells

38. The chemical must dissolve in the watery fluid surrounding the taste buds that are produced by the salivary glands.

39. 1. Sweet—table sugar 2. Sour—lemon 3. Salty—table salt 4
1. Sweet—table sugar 2. Sour—lemon 3. Salty—table salt 4. Bitter—caffeine or quinine

40. It detects monosodium glutamate (MSG), used as a flavor enhancer in many prepared foods

41. 10.7 Sense of Hearing ( )

42. Auricle (pinna)—outer ear; External Auditory meatus

43. malleus, incus, stapes - transmit vibrations and amplify the signal

44. Eustachian tube; Connects the middle ear to the throat; Helps maintain air pressure

45. Labyrinth, semicircular canals, cochlea, round window, and organ of Corti

46. Labyrinth: communicating chambers and tubes
Labyrinth: communicating chambers and tubes Osseous Labyrinth and Membranous Labyrinth Perilymph and Endolymph (fluids within the labyrinth)

47. Semicircular Canals: sense of equilibrium

48. Cochlea: sense or hearing

49. Organ of Corti: contains hearing receptors, hair cells detect vibrations

50. Hair cells

51. 10.8 Sense of Equilibrium (264-267)

52. It senses the position of the head and maintains stability and posture

53. It balances the head during sudden movements; Semicircular canals

54. It interprets impulses from the semicircular canals and maintains overall balance and stability