1. Receptors and General Senses
Lab 30
Receptors and General Senses

2. Materials Needed Direction packet
Lab Report 30 worksheet (1 per person)
Textbook
Pen (washable)
Ruler (mm)
Sharp pencil/sharp point of lead/ or paper clip point
Blunt metal probe
Forceps
Warm water
Ice water
Paper towel

3. Procedure B
1. Investigate the distribution of touch receptors in your lab partner’s skin.
Draw a 2.5 x 2.5 cm square on your partner’s inner wrist, near their palm
Draw a 2.5 x 2.5 cm box
Then draw a line every .5 cm
Horizontally
Vertically
2.5 cm x 2.5cm

4. Procedure B
Investigate the distribution of touch receptors in your lab partner’s skin. c. Ask your partner to rest their wrist on the table and to CLOSE THEIR EYES
2.5 mm x 2.5mm

5. Procedure B
Investigate the distribution of touch receptors in your lab partner’s skin.
Press the end of a sharp pencil in a square on the grid, using light pressure
Ask your partner to report whenever the touch is felt. Record in lab report.
+ if felt
0 if NOT felt
Continue until you test all 25 locations on the grid. GO IN RANDOM ORDER.
2.5 mm x 2.5mm

6. Procedure B
Investigate the distribution of touch receptors in your lab partner’s skin.
Test two other areas of exposed skin.
Palm
Your choice
2.5 mm x 2.5mm

7. Procedure B
Investigate the distribution of touch receptors in your lab partner’s skin. Answer questions in part B of lab report.
2.5 mm x 2.5mm

8. Procedure C
Test your partner’s ability to recognize the difference between one and two points of skin being stimulated simultaneously. a. Have your partner place a hand with the palm up on the table and close eyes.

9. Procedure C
Test your partner’s ability to recognize the difference between one and two points of skin being stimulated simultaneously. b. Hold the tips of the forceps tightly together and gently touch the skin of your partners index finger. c. Ask your partner to report if it feels like one or two points are touching their finger

10. Procedure C
Test your partner’s ability to recognize the difference between one and two points of skin being stimulated simultaneously. d. Allow the tips of the forceps or the points of the tips to spread so they are 1 mm apart. Press both points against the skin simultaneously, and ask your partner to report.

11. Procedure C
Test your partner’s ability to recognize the difference between one and two points of skin being stimulated simultaneously.
e. Repeat, allowing the tips of your forceps to spread more each time UNTIL YOUR PARTNER CAN FEEL BOTH TIPS
This is called the two-point threshold. As soon as you can feel this, two receptors are being stimulated, instead of one!
f. Record results

12. Procedure C
Test your partner’s ability to recognize the difference between one and two points of skin being stimulated simultaneously.
Repeat on:
Palm
Back of hand
Leg
Sole of foot –or ankle if you want
Answer the questions in part C

13. Procedure D
Investigate the distribution of warm receptors in your partner’s skin Using the grid on your palm from procedure A, have your partner rest their hand on the table and close their eyes

14. Procedure D
Investigate the distribution of warm receptors in your partner’s skin d. Heat the blunt metal probe by placing it in your cup of hot water (BE CAREFUL!!!) for a minute or so. e. Wipe probe dry and touch it to the skin on some part of the grid

15. Procedure D
Investigate the distribution of warm receptors in your partner’s skin
f. Ask your partner to report if the probe feels warm. Record in part D. Keep the probe warm, and repeat until you have RANDOMLY tested all 25 squares
+ if felt
0 if NOT felt

16. Procedure D
Investigate the distribution of cold receptors in your partner’s skin Repeat using ice water. Answer the questions in part D of the lab report

17. Other Directions: WORK IN PARTNERS
Share materials with another set of partners
NO ICE OR HOT WATER WILL BE AVAILABLE TOMORROW!!!!! So you MUST complete procedure D today.
You will have limited time in class tomorrow to finish Lab report 30
Approx 15 mins (MAX)