Experiment 4 Skin Receptors The receptors for the sense of touch are distributed across the surface of the entire body However certain parts of the body are more sensitive to touch than others as they have a higher concentration of the receptors in that area In this activity you will determine which areas of your body are most sensitive to touch Materials 16 Paperclips Ruler Tape Partner You must provide Procedure 1 Make a caliper by unwinding two of the paperclips until they are straightened Then bend each paperclip in the middle to form a U shape There should be approximately 0 5 cm between the two tips of each paperclip after being bent into a U shape 2 Tightly wrap each tip with a small piece of adhesive tape This minimizes any sharp points on the paperclip See Figure 7 Figure 7 Paperclip shape reference 3 Repeat Steps 1 2 for the remaining paperclips with the ends set 1 0 1 5 2 0 2 5 3 0 3 5 and 4 0 cm apart When finished you should have two calipers for each other the eight possible sizes 4 To test the sensitivity of different body regions ask your partner to close his her eyes Start with the largest caliper the one with 4 0 cm between the tips and place both tips of the paperclip onto the left side of your partner s scalp Do NOT tell your partner if you place one or both of the tips on his her head 5 Ask your partner how many points s he can distinguish If s he can feel two points move on to the 3 5 cm caliper and test again your partner should keep 2013 eScience Labs LLC All Rights Reserved his her eyes closed Repeat until your partner can only feel one point Record the caliper size at which only one point can be felt in Table 3 6 Continue to test different regions on the left side of the body Use Table 3 to select body regions 7 Repeat Steps 4 5 on the right side Observe if there is a difference between the left and right sides of the body and record your results in Table 3 Table 3 Two Point Discrimination Test Results Body Region Left Side Caliper Measurement Right Side Caliper Measurement Scalp 2 0cm 1 5cm Forehead 1 5cm 2 0cm Lips 5cm 0cm Front of Neck 0cm 2 0cm Back of Neck 0cm 2 0cm Shoulder 1 5cm 2 5cm Upper Arm 5cm 3 0cm Elbow 1 0cm 2 0cm Forearm 1 5cm 1 0cm Wrist 1 5cm 0cm Back of Hand 1 0cm 1 0cm Palm of Hand 5cm 0cm Tip of Thumb 0cm 0cm Tip of Second Finger 0cm 0cm 1 0cmTip of Third Finger 0cm 0cm Tip of Fourth Finger 0cm 0cm Tip of Fifth Finger 0cm 5cm 2013 eScience Labs LLC All Rights Reserved Post Lab Questions 1 Which region was most sensitive to this test Which was least sensitive The palm of the hands and the fingertips were the most sensitive The least sensitive spots were scalp forehead forearms shoulders and the elbows 2 Can you think of an advantage to having a greater distribution of touch receptors in the area that you found to be most sensitive It is an advantage to be most sensitive in your hands and fingertips because you hold and grab things often and it is good to be able to feel what is in your hands easily 3 Was there a difference between the measurements of the left and right side of the body Why or why not Yes my partner was a lot less sensitive on the right side of the body I am not sure why this was the case There is no definite reason 2013 eScience Labs LLC All Rights Reserved
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