PHYSIOLOGY OF THE SKIN
I. Materials Needed:
Glass plates, Two squares of bond papers (1cm x 1cm each), adhesive tape, betadine or Lugol's solution, Cotton Swab
A. Visualizing Changes in Skin Color Due to Continuous External Pressure
1. Obtain a small glass plate or watch glass.
2. Press the heel of your hand firmly against the plate for a few seconds.
3. Observe and record the color of your skin in the compressed are by looking through the back of the glass.
1. What is the color of the compressed skin?
2. What is the reason for this color change?
What would happen if the pressure was continued for an external period in this area?
3. Cite three abnormal variations in skin color and the indicative condition associated with them.
B. Plotting the Distribution of Sweat Glands
1. Obtain two squares of bond paper (1cm x 1cm), adhesive tape and a betadine solution or Lugol's iodine and cotton-tip swab.
2. Using the iodine solution, point an area of the medial aspect of the left palm (avoid the crease line) and a region of the left forearm. Allow the iodine solution to dry thoroughly. The painted area in each case slightly larger than the paper squares to be used.
3. Mark one piece of ruled bond paper with an "ll" for hand and the other "A" (for arm). Have your laboratory partner securely tape the appropriate square of board paper over each iodine-painted area, and leave them in place for 20 minutes. (If it is very warm in the laboratory, good results can be obtained within 10-15 minutes).
4. After 20 minutes, remove the paper squares and count the number of blue-black c=dots in each square. The appearance of the blue-black dot on the paper indicates an active sweat gland. (The iodine in the pore dissolves in the sweat and reacts with the starch in the paper to produce the blue-black color). Thus sweat "maps" have been produced for the skin areas.