Hands on Lab 9: Tactility (Touch), Gustation (Taste), and Olfaction (Smell). 4 Activities
Submission Instructions
· Type your answers and copy all pictures directly into this Word document. Submit it via the Blackboard submission link in Word format (docx).
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). Similar to other labs you’ve done, here you will learn and label structures and apply your knowledge with some experiments.
Watch These:
Homunculus (Link opens in new window: 10min). This Crash Course video is from their psychology series but has a nice overview of all of the human senses you will work with in this lab. This video brings together the senses and shows how it ties in to what you’ve completed in previous labs. Plus, you’ll learn what a homunculus is !
TED-Ed How do we smell (link opens in new window: 4 min). This video goes into the basics of how our sense of smell work and discusses sensory adaptation. Have you ever wondered what your home smells like? Watch this to see why it may smell different to someone coming in your home for the first time versus you.
There are 3 brief videos embedded in the gustation activity as well.
Activity 1: Two-Point Discrimination
Different parts of your skin have different numbers of nerves running to them, which effects the level of sensation. For this activity, you will use a compass to conduct a two-point discrimination test with a partner. You may have had a similar test in a doctor’s office if they were ever checking your nerve function.
Materials: Compass (drafting, not navigational), ruler, pencil.
Start with the compass as close together as it will go. You will want to make sure that the pencil tip is even with the tip of the compass. You will 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.
For example: If your partner first detects 2 points on their cheek and you measure 3mm distance between the pencil point and the compass tip, you would enter that in the table.
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 body 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 areas do you think have more receptors in the skin: areas with small two-point distances or large two-point distance?
3. Which takes up more real estate/area in the brain: areas of skin with lots of receptors or from skin with a few receptors? Why?
4. List the different types of tactile receptors (Ex: Free nerve endings) in our skin and what sensation they each detect.
5. Out of the tactile receptors you listed in #4, which one is primarily associated with the two-point discrimination test?
Activity 2: Does Smell (Olfaction) Effect Taste (Gustation)?
Have you ever had a head cold and experienced a loss of appetite/food not tasting that good? Let’s explore why. In this experiment, you 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: Small bag of multi-flavored jellybeans (alternate candies with at least 5 different flavors work as well-please contact your instructor with any questions on acceptable alternatives).
Procedure: Both you and the volunteer should complete both parts of the experiment. Tables for data collection are below the procedure.
Part 1:
· Sit with your eyes and nose closed (use nose clips or pinch off your nostrils).
· Your lab partner should hand you each sample one at a time in random order.
· Taste each sample with your nose and eyes closed.
· After you have tasted the sample, try to identify the flavor
· Your partner should record your accuracy (flavor correct/incorrect) and your confidence levels (1=no idea of flavor, 10=certain of flavor).
Part 2:
· Release your nostrils but still keep your eyes closed and repeat the experiment.
· Record the confidence level.
Part 3:
· Switch places with your partner, repeat the experiment, and record the results.
Sample Flavor
Nose/Eyes Closed Accuracy (correct/incorrect)
Nose Closed
Confidence
(1-10)
Nose Open
Confidence
(1-10)
Subject 1
1
2
3
4
5
Subject 2
1
2
3
4
5
Questions:
6. Did your subjects correctly identify the flavors during the first session (nose closed)? Did their confidence and accuracy correspond?
7. In the second session (nose open) did their accuracy and confidence correspond?
8. In 1-2 sentences, summarize the results of this experiment.
9. Based on your results and watching this video from PBS NOVA (link opens in new window ~4min), how would you describe the connection between taste and smell (1-2 sentences)?
Activity 3: Gustation
10. List the 5 primary tastes and the compound that produces each taste sensation (all must be correct for credit. Ex Sweet = sugars). Note *Even though we have areas of the tongue where we can experience these tastes the strongest, all 5 tastes may be experienced throughout the entirety of the tongue.
11. One way we classify receptors is by the stimulus (Ex: mechanoreceptor). What stimulus classification would you assign to taste buds?
12. Some people are known as supertasters. Take a look at this NOVA video (link opens in new window ~2 min). What is different about their tongues? Do you think you may be a supertaster?
Use the diagram below to answer 13-16:
13: What is the structure at A?
14. What is the structure at B?
15. What is the structure at C?
16. What is the structure at D?
You now know the basic structure of the tongue and all about taste. What about when you eat something spicy and your tongue feels hot? What receptors are those? Watch this video on The Science of Spice (link opens in new window ~4 min) and answer #17 and 18 below.
17. Spice is not a taste. What sensory neurons are activated when you eat something hot?
18. Why do wasabi and chili peppers give you the sensation of burning in different areas?
Activity 4: Olfaction
Identify the various structures, tissues, and cells within the nasal cavity. Each letter will only be used once. Diagram on next page.
19. Olfactory bulb =
20. Olfactory tract =
21. Connective layer =
22. Cribriform plate =
23. Supporting cell =
24. Olfactory Neuron =
25. Olfactory Cilia =
26. Basal cell =
27. Nasal cavity =
28. Axon =
29. Olfactory epithelium =
30. Mucous layer =
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