DB 5 & Hands On Lab Senses

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Hands On Lab: Senses

Grading: Divide number incorrect by total number of questions (59)

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Introduction

Senses are how we connect to the world. There are five special senses: vision, hearing, olfaction (smell), gustation (taste), and equilibrium (balance). In addition to that, there are tactile sensors in the skin and many internal senses that you are unaware of (such as those for blood pressure or blood sugar).

Activity 1: Two-Point Discrimination

Different parts of your skin have different numbers of nerves running to them, which effects level of sensation. Close your eyes or have someone close theirs. Use the compass to touch the person’s skin with the compass in the areas indicated in the chart.

Materials

· Compass (drafting, not navigational= see picture)

· Ruler

Start with the compass as close together as it will go and progressively get wider with each touch until the person can detect 2 points instead of one; then use the ruler to measure the distance and record it in the chart. Do this for each area.

Skin Area For Testing	Minimum Distance for 2-Point Discrimination in Millimeters (mm)
Forehead
Cheek
Palm of Hand
Tip of Index Finger
Forearm
Tip of Thumb
Back of Lower Leg
Back of Neck

Questions

1. Are the two-point distances on different areas of the skin the same? Why or why not do you think this is? If they are not the same, which area was the most sensitive and which area was the least sensitive?

2. Which skin areas do you think have more receptors, areas that have small two point distances or large two-point distances? Why?

3. Which brain area do you think is larger, one receiving information from skin with lots of receptors or from skin with a few receptors? Why?

4. What are the different types of tactile receptors in our skin and what sensation(s) does each detect?

5. Which tactile receptor is most involved with 2-point discrimination?

Activity 2: Olfaction

Identify the various structures, tissues, and cells within the nasal cavity. Each letter will only be used once.

6. Olfactory bulb

7. Olfactory tract

8. Connective layer

9. Cribriform plate

10. Supporting cell

11. Olfactory neuron

12. Olfactory cilia

13. Basal cell

14. Olfactory nerve

15. Nasal cavity

16. Axon

17. Olfactory epithelium

18. Mucous layer

Activity 3: Does Smell Effect Taste?

Have you ever noticed how a cold affects your appetite? In this experiment, we will test how well you can guess flavors when you cannot see or smell the samples you are tasting. You will need one volunteer and of course, yourself.

Materials

· Five different types of fruit juice (or alternate flavored liquids)

· 10 small drinking cups

· Marking pen

Procedure

Both you and the volunteer should complete both parts of the experiment. One group member can manage the experiment, while the other sips the solutions and then switch roles.

Part 1:

1. Sit with your eyes and nose closed (use nose clips or pinch off your nostrils).

2. Your lab partner should hand you each sample one at a time in random order.

3. Taste each sample with your nose and eyes closed.

4. After you have tasted the sample, try to identify the flavor.

5. Your partner should record your accuracy (flavor correct/incorrect) and your confidence levels, ranging from 1 (no idea of flavor) to 10 (certain of flavor).

Part 2:

6. Release your nostrils but still keep your eyes closed and repeat the experiment, again recording results.

Part 3:

7. Switch places with your partner and repeat the experiment.

Subject 1

Sample Flavor	Nose Closed Accuracy (correct/incorrect)	Nose Closed Confidence (1-10)	Nose Open Accuracy (correct/incorrect)	Nose Open Confidence (1-10)
1
2
3
4
5

Subject 2

Sample Flavor	Nose Closed Accuracy (correct/incorrect)	Nose Closed Confidence (1-10)	Nose Open Accuracy (correct/incorrect)	Nose Open Confidence (1-10)
1
2
3
4
5

Questions

19. What are the five primary tastes?

20. What type of receptor by stimulus classification are taste buds?

21. Where are the taste buds located?

22. Which cranial nerves sends smell signals and what structure(s) does each innervate?

23. Which cranial nerves sends taste signals and what structure(s) does each innervate?

24. Did your subjects correctly identify the flavors during the first session (nose closed)? How confident were they? Did their confidence and accuracy correspond, were they wrong when they thought they were correct, or correct when they thought they were wrong?

25. Did your subjects correctly identify the flavors during the second session (nose open)? How confident were they? Did their confidence and accuracy correspond, were they wrong when they thought they were correct, or correct when they thought they were wrong?

Activity 4: Parts of the Eye

Identify the various structures, tissues, and cells within the eye. Each letter will only be used once.

26. Sclera

27. Ciliary body

28. Optic nerve

29. Suspensory ligaments

30. Lens

31. Choroid

32. Pupil

33. Vitreous chamber

34. Anterior chamber

35. Retina

36. Cornea

37. Iris

38. Conjunctiva

Activity 5: Retinal Histology

Identify the various layers and cells within the retina. Each letter will only be used once.

39. Bipolar layer

40. Cone

41. Ganglia layer

42. Choroid

43. Pigmented layer

44. Rod

45. Photoreceptor layer

Activity 6: Parts of the Ear

Identify the various structures, tissues, and cells of the ear. Each letter will only be used once.

46. Auditory ossicles

47. Cochlea

48. Auricle

49. Malleus

50. External auditory canal

51. Incus

52. Semicircular canals

53. Vestibulocochlear nerve

54. Vestibule

55. Round Window

56. Oval window

57. Auditory (Eustachian) tube

58. Stapes

59. Tympanic membrane