Integumentary System: L1

 

 

 

 

Integumentary System: 

Lab Exercises

The Integumentary system includes the skin, hair, nails, sebaceous glands, and sweat glands. These organs provide a protective covering for deeper tissues, aid in regulating body temperature, prevent water loss, get rid of wastes, and aid in communication using sensory receptors.

 

Laboratory Activity 1: Visualizing Changes in Skin Color due to Continuous External Pressure

 

Materials

  • glass plate

 

Procedure:

  • Firmly press the heel of your hand against
    the glass for a few seconds..

  • Observe and record the color of your skin in
    the compressed area by looking through the glass.

Data:

  1. Observe and describe the color of your skin in the compressed area by looking through the glass.

     

  2. What is the color of the compressed skin?

     

  3. Why does the color of the skin change?

     

  4. What would happen if the pressure was continued for an extended period in this area?

 

Laboratory Activity 2: Types of skin cells

 

Materials

  • Prepared Slides

  • Microscope

 

Procedure:

  • Use the microscope to observe slides

 

 

Data:

Analyze the three provided cell slides using a microscope under medium to high power. 

Draw and label what you see.  Indicate the magnification used with the microscope.

 

 

 

 

 

 

 

 

 

Areolar Tissue x______

Stratified Squamous x_____

Stratified Squamous x_____

Laboratory Activity 3: Testing Tactile Localization

 

Skin has many sensory “touch” receptors. Tactile localization is the ability to determine which portion of the skin has been touched.  Once the skin’s sensory receptors have received a message it sends this message to the brain and then the brain interprets the location and “meaning” of the feeling. (rough, smooth, soft, tickly, painful, ect…) The more sensory receptors in an area of the skin, the more accurately the brain can interpret the location.

 

Materials:

  • Fine Point Markers

  • Ruler

 

Procedure:

  • Make sure your subject’s eyes are closed. 

  • Experimenter touches the palm of the subject’s hand with a marker.

  • Subject should then try to touch the exact point with his/her own marker (different color). 

 

Data Collection:

  • Using a ruler, measure the error of localization in millimeters (the distance between the 2 marks).

  • Repeat the test in the same spot two more times, recording the error of localization for each test.

  • Average the results of the three trials and record your data in the chart.

  • Repeat this procedure on the fingertip, ventral forearm,  and the back of hand.

                                    

 

Data:

  1. Does the ability to localize the stimulus improve the second time? __________ The third time? ___________

  2. Why do you think this happened? _______________________________________________________________

  3. Which area has the smallest error of localization and is therefore the most sensitive to touch? ___________

Body Area Tested         1st Trial             2nd Trial           3rd Trial            Average error

                                                                                                                      of localization

 

Palm of hand

 

 

Fingertip

 

 

Ventral forearm

 

 

Back of hand

Laboratory Activity 4: Determining the Two-Point Threshold

 

The density of the touch receptors varies significantly in different areas of the body. In general, areas that have the greatest density of tactile receptors have a heightened ability to “feel.”

 

Materials:

  • Pins

  • Clay

 

Procedure:

  • Push the back of two pins into a small ball of clay and touch the tips of the pins together. 

  • Starting with the face, touch the skin of the subject with both pins simultaneously and gradually increase the distance until the subject reports that two points of contact can be felt. 
    (This measurement, the smallest distance at which two points of contact can be felt, is the two-point threshold).

  • Repeat  procedure for the other locations in the data table.


Data:

Body area tested                                          Two-Point Threshold (millimeters)

 

Face

 

Back of hand

 

Palm of hand

 

Fingertip

 

Lips

 

Back of neck

 

Ventral forearm

Laboratory Activity 5: Demonstrating Adaptation of Touch Receptors

 

In many cases, when a stimulus is applied for a long period of time, the rate at which the receptors respond slows down.  Your awareness of the stimulus declines or is lost until a change in the stimulus occurs.  This is referred to as ADAPTATION. The touch receptors adapt.

 

Materials:

  • Quarter-dollar Coin
     

Procedure:

  • Make sure your subject’s eyes are closed.

  • Place a coin on the anterior surface of the subject’s forearm
    determine how long the sensation persists for the subject.


Data:

  • Using a timer, record the duration of the sensation in seconds __________

  • Repeat the test, placing the coin at a different forearm location.
    Record the
    duration of the sensation ________________________________

 

  • After awareness of the sensation has been lost at the second site,
    stack three
    more coins atop the first one (total 4 coins).

  • Ask subject if the pressure sensation return? ___________

  • If so, record the duration of the sensation. _________________________________

  • Are the same receptors being stimulated when the four coins, rather than one coin, are used?
    Explain your reasoning______________________________________________________________________

Laboratory Activity 6:  Examination of Hair 

 

Hair is a form of protection and helps to maintain body temperature.  The hair follicle is structured from both the epidermal and dermal cells. If you look carefully at the structure of the hair follicle you will see that it generally is in a slanted position. Small bands of smooth muscle cells – arrector pili – connect each hair follicle to the dermis. When these muscles contract the hair follicle is pulled upright, dimpling the skin surface causing the appearance of goosebumps.

 

Materials:

  • MIcroscope

  • Microscope Slide

 

Procedure:

  • Rub your fingers across your eyebrow and see it you can pluck an eyebrow hair to view under the microscope.

  • Once you’ve obtained your piece of hair, make a dry mount slide and view it under the microscope.

  • Examine the hair under low power, then medium, and then high power. Look for the small scale like structures of the hair shaft and the bulb. Illustrate your observation when viewing under medium or high power. 

    Be sure to document the total magnification of the image your drew.
    Repeat steps 2 & 3 using an eyelash and a piece of hair from your head.


Data

  1. How are the hairs similar?___________________________________________________________

  2. How are the hairs different?____________________________________________________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Arm Hair x_____

Eyebrow Hair x______

Head Hair x_____

Laboratory Activity 7:  Plotting Distribution of Sweat Glands 

 

The appendages of the skin (hair, nails, sweat glands and oil glands) are all seen on the epidermis, but they begin in the dermis.  Pores are the outlets for sweat glands and are widely distributed in the skin.

The sweat glands are controlled by the nervous system and are an important part of regulating the temperature of the body.  The sweat glands secrete perspiration when the body temperature gets too high. When the perspiration evaporates off the skin it carries large amounts of body heat with it.

 

Materials:

  • 1 cm paper Squares

  • Iodine Solution

  • Cotton Swab
     

Procedure:

  • Using the iodine solution, paint an area of the left palm of your hand (avoid the creases) and a region of your left forearm.  The painted area should be slightly larger than the paper squares to be used.  The paper should be about 1 cm2.

  • Allow the iodine to dry.

  • Mark one paper square with an “H” (for hand) and the other with an “A” (for arm).  Tape each paper square over each iodine-painted area, and leave them in place for 15 minutes.

  • After 15 minutes, remove the paper and count the number of blue-black dots on each square.
    (The appearance of a blue-black dot indicates the appearance of an active sweat gland.) 


    The sweat in your pore dissolves the Iodine, which reacts with the starch in the paper to produce the color.

 

Data:

  1. Which skin area tested has more sweat glands?______________________________________________