Procedure Bsense Of Touch

1. Investigate the distribution of touch receptors in your laboratory partner's skin. To do this, follow these steps:

a. Use a marking pen and a millimeter ruler to prepare a square with 2.5 cm on each side on the skin of your partner's inner wrist, near the palm.

b. Divide the square into smaller squares with 0.5 cm on a side, producing a small grid.

c. Ask your partner to rest the marked wrist on the tabletop and to keep his or her eyes closed throughout the remainder of the experiment.

Figure 31.1 Meissner's corpuscles, such as this one, are responsible for the sensation of light touch (250x).

Epidermis

Meissner's corpuscle in dermal papilla

Dermis

Figure 31.1 Meissner's corpuscles, such as this one, are responsible for the sensation of light touch (250x).

Epidermis

Meissner's corpuscle in dermal papilla

Dermis

Figure 31.2 Pacinian corpuscles, such as this one, are responsible for the sensation of deep pressure (25x micrograph enlarged to 100x).

Dermis

Figure 31.2 Pacinian corpuscles, such as this one, are responsible for the sensation of deep pressure (25x micrograph enlarged to 100x).

Dermis

Pacinian corpuscle

Nerve fiber

Pacinian corpuscle

Nerve fiber d. Press the end of a bristle on the skin in some part of the grid, using just enough pressure to cause the bristle to bend. A sharp pencil could be used as an alternate device.

e. Ask your partner to report whenever the touch of the bristle is felt. Record the results in Part B of the laboratory report.

f. Continue this procedure until you have tested twenty-five different locations on the grid. Move randomly through the grid to help prevent anticipation of the next stimulation site.

2. Test two other areas of exposed skin in the same manner, and record the results in Part B of the laboratory report.

3. Answer the questions in Part B of the laboratory report.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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