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Biology

Biology Lab: Nerve Sensitivity — Pressure and Temperature

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Lab Exercise

Biology Lab: Nerve Stimulation and Sensitivity

Goal: To determine skin sensitivity to touch and heat stimuli.

Materials

Procedure A: Heat Sensitivity

  1. The subject should place the index finger in the coldest water (ice water) , then room temperature water, then hot water. Report the sensations. Be sure that the subject can distinguish between the three temperatures by touch.
  2. Replace the index finger in the ice water and hold it for at least 20 seconds.
  3. Now place the whole hand in the ice water. Record your sensations.
  4. Repeat by placing first the index finger, then the whole hand in the hot water, and record the sensations.
  5. Does the index finger sense the heat or cold differently than the rest of the hand?

Procedure B: Touch sensitivity

  1. Have the test subject close his or her eyes and hold out one hand.
  2. Touch the skin on the palm of the hand lightly with one or two points of the straight pins held close together (the points should nearly touch).
  3. The subject should report the sensation as "one" or "two" points.
  4. Repeat, moving the pins apart slightly each time, until the subject reports a two-point stimulus 75% of the time (3 out of 4 tries). Record this distance as the "two point distance for the palm".
  5. Repeat the above procedure and discover the two-point distance for the inner surface of the forearm, the back of the neck, the middle of the back, and the tip of the index finger.
  6. Determine which area is the most sensitive to touch.

Data Analysis

Determine the best way to present your data. Are there any trends you can look for? Can the data be arranged in graphs or tables, or is it best explained as a narrative?

Report

Follow the standard report format outlined in the Student Survival Guide.

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