Integumentary system laboratory sheet

What is the Integumentary system?

The integumentary system includes the hair and nails, which are organs that grow
out of the skin. Because the organs of the integumentary system are mostly external to
the body, you may think of them as little more than accessories, like clothing or
jewelry, but they serve vital physiological functions. They provide a protective
covering for the body, sense the environment, and help the body maintain
homeostasis.

The Skin

The skin is remarkable not only because it is the body’s largest

organ. It is remarkable for other reasons as well. The average
square inch of skin has 20 blood vessels, 650 sweat glands, and
more than a thousand nerve endings. It also has an incredible
60,000 pigment-producing cells. All of these structures are packed
into a stack of cells that is just 2 mm thick, or about as thick as the
cover of a book. Although the skin is thin, it consists of two distinct
layers, the epidermis and dermis, as shown in the diagram below.

Layers of the Skin

 Epidermis, the outermost layer of skin, provides a waterproof barrier and

creates our skin tone.
 Dermis, beneath the epidermis, contains tough connective tissue, hair follicles,
and sweat glands.
 Subcutaneous tissue (hypodermis) is made of fat and connective tissue.

Objectives :

After completion of this lab, you should be able to: 

1. Describe the distribution of cutaneous touch and temperature receptors. 

2. Describe the inflammatory response and determine what triggers it. 
3. Label the different layers and structures of the skin.

A. Cutaneous Receptors Touch Receptors:

The density of the touch receptors varies significantly in from one part of the body
to another. In general, areas that have the greatest density of tactile receptors have
a heightened ability to “feel”. These areas correspond to areas that receive the
greatest motor innervation; thus they are also typically areas of fine motor control.
Areas with a higher density of receptors should allow you to pinpoint touch more
accurately than areas with fewer tactile receptors.

Let’s check it out. Follow the directions below:

1. Obtain a ball point pen and a ruler with millimeter divisions.

2. With your eyes closed, have your lab partner touch the palm of your hand with a
pen. The touch should be gentle enough not to hurt, but firm enough to leave a
small mark.
3. Keeping your eyes closed, try to place the tip of the pen on the spot touched by
your lab partner. Once you think you’ve found it, hold it there.
4. Have your lab partner measure the distance in millimeters between the two spots.
Record the distance in the table below.
5. Repeat the steps two more times. Average the results.
6. Repeat the experiment on the back of the hand, a fingertip, the ventral surface of
the forearm, and the back of the neck. Record and average the results.

Table 1. Distance Between Touch Spot and Guess Body Region

BODY First Trial(mm) Second Third trial Average (mm)

REGIONS Trial(mm) ( mm)

Palm of Hand 8mm 9mm 9mm 9mm

Back of Hand 15mm 5mm 15mm 12mm
Fingertip 1mm 4mm 7mm 4mm
Forearm 6mm 8mm 12mm 9mm
Back of neck 25mm 15mm 25mm 22mm

Analysis Questions:

1. Did the distances get smaller by the third trial? In other words, did you get better
at pinpointing the spot touched?

-No, it did not get better at pinpointing the spot touched

2. Which area was the most sensitive?

- For me it is my fingertips

3. What reason can you give for the difference in sensitivity between the fingertip
and the back of the neck? Why is one area more sensitive than the other?
 - Because our fingertips have touch receptors than the back of my neck, the
receptors in our skin are not distributed in a uniform way around our bodies.
Some places, such as our fingers and lips, have more touch receptors than
other parts of our body, such as our backs. That is one reason why we are
more sensitive to touch on our fingers and face than on our backs.

4. Does the difference in sensitivity between the fingertip and the back of the neck
help our bodies to maintain homeostasis? If so, in what way?

- Yes because homeostasis is the various physiological processes to keep

internal state steady and balance so if there’s any changes like in body
temperature either its cold or hot, fluid balance etc homeostasis were the
one keeping our body in normal like keeping our body in average
temperature. Homeostasis help maintain the set point temperature; it’s the
maintenance in our body especially when in it comes in sensitivity in touching
or feeling on something.

B. Temperature Receptors:

Our skin contains thermoreceptors that sense temperature. Some thermoreceptors

sense heat, while others sense cold. This activity will demonstrate the presence of
both types of receptors in your skin.

Materials:

500 ml beaker containing hot tap water

500 ml beaker containing ice water

2 glass stirring rods

Roll of masking tape

Paper towels

Follow the directions below:

1. Fill one 500-ml beaker about halfway with water then add ice. Fill the second 500-
ml beaker about halfway with hot water (from the tap).
2. In each beaker, place a thin glass probe. Allow the probe temperature to
equilibrate (1 or 2 minutes). While you’re waiting, use a pen or masking tape to mark
off a square (~2cm x 2cm) on the back of your partner’s hand.
3. Have your partner close his or her eyes. Remove one of the glass probes (don’t say
which one!), wipe it dry with a paper towel, then place it in one corner of the square.
Ask your partner to identify whether the sensation is warm or cool.
4. Record your data in the square below by writing an H where your partner feels
hot and a C where your partner feels cold.
5. Repeat two times with the hot probe and two times with the cold probe in
different locations in the square. Remember not to tell which one you’re testing.

Analysis Questions:

1. How are thermoreceptors distributed compared to touch receptors?

- Thermoreceptors are distributed by detecting the temperature whether it’s

cold or hot.

2. Do you think that your fingertips have more concentrated thermoreceptors than
the back of your hand?

- Yes, because fingertips have more sensory neurons, also it is the most sensitive
parts to pain and have more touch receptors than the back portion of your hand.

3. How does the presence of thermoreceptors help our bodies to maintain

homeostasis?
4. - The presence of thermoreceptors help our bodies to maintain homeostasis
because thermoreceptors are the key for detecting the changes in temperature so
that the body can adjust to this changes for survival and it’s a part of the process of
maintaining homeostasis.

C. Inflammatory Response

The nervous and cardiovascular systems respond to certain stimuli by triggering an

inflammatory response. The stimuli could be an infectious agent, foreign body like a
splinter, burns, lacerations, toxins, or even chemicals. The inflammatory response is
the body’s attempt to remove the stimuli and protect the body from infection.
Depending on the severity, the inflammatory response can involve swelling, heat,
redness, and pain. The blood vessels increase blood flow to the inflamed area,
causing heat and redness. As the blood accumulates in the area, it also causes
swelling.

Follow the directions below:

Obtain a pencil with an eraser, a timer, and a ruler.

The White Reaction

1. Have the timer ready and drag the eraser lightly across the skin of the forearm.
2. Start the timer.
3. Immediately observe the area that the eraser was dragged over. Watch for a
white streak. Record the time it takes for the white streak to appear in Table 2
below. Continue timing.
4. Record the time it takes for color to return to the white area in Table 2. NOTE -
The white reaction is caused by the displacement of blood from the small capillaries
at the surface of the skin in response to the mechanical stimuli. Eventually blood will
return to the area.

The Red Reaction

1. On the other forearm, drag the eraser firmly across the skin of the inner forearm.
This should be slightly painful.
2. Start the timer.
3. Immediately observe the area that the eraser was dragged over. Watch for a red
streak with a white halo.
4. Record the time it takes for the red streak to appear in Table 2.
5. Continue watching the streak for the next few minutes to determine if you have
dermographia. Some individuals will have a more severe allergic reaction caused by
very sensitive skin that overproduces histamine in response to the stimuli. A
dermographic reaction will produce a raised swollen welt.
6. Watch for a raised swollen welt where the eraser was dragged over. Record
whether a welt appeared or not in Table 2. If a welt appeared, you have
dermographia.

Table 2

Time for white Time for white Time for red Do you have
reaction to reaction to reaction to Dermographia?
appear disappear appear
Time in 1 sec. 2 seconds 31 seconds no
Seconds

Analysis Questions

1. What triggers an inflammatory response?

 - When your immune system becomes activated when your body recognizes
anything that is foreign such as an invading microbe plant pollen, or chemical and it
occurs when tissues are injured by bacteria, trauma toxins, heat, or any other cause.
The damage cells release chemicals including histamine, bradykinin, and
prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues
causing swelling.

2. What are the symptoms of an inflammatory response?

- Redness (rubor), swelling (tumuor), heat (calor; only applicable to the body
extremities), pain (dolor) and loss of function (function laesa).

3. What is the difference between a white and a red reaction?

- The white reaction the mast cells are not damaged, it may occur when a
blunt point is stroked with light pressure across normal skin. Blood is
displaced temporarily from the superficial vessels of the skin, but the stroked
portion becomes paler than the surrounding skin within 10 to 15 seconds
while the red reaction red reactions occurs within 30sec, the flare refers to
the erregularly outlined area of red skin spreading beyond the red line.- the
flare is due to an axon reflex.

4. What is dermographia? Do you have it?

- It is a condition also known as skin writing. People have dermatographia

lightly scratch their skin, the scratches redden into a raised wheal similar to
hives. These marks usually disappear within 3o minutes.
- I don’t have this condition (dermatographia)

5. How does the inflammatory response help our bodies maintain homeostasis?

- Inflammatory response help our bodies maintain homeostasis by

coordinating immune function including T cells mediation to identify and
eliminate cancer cells .T- Lymphocytes or T cells are involved in:
1) inflammatory reactions. 2) increasing the numbers of cells for a strong
defense of the body.
 Name the labeled parts of the skin

Source: http://pshs.psd202.org/documents/smckinne/1505435202.pdf

Parts of the skin:

1. Stratum Corneum
2. Stratum Lucidum
3. Stratum Granulosum
4. Stratum Spinosum
5. Stratum Basale
6. Epidermis
7. Dermis
8. Hypodermis/ Subcutaneous
9. Sensory nerve ending for touch
10. Pacinian Corpuscle
11. Hair
12. Dermal Pappilae
13. Arrector Pili Muscle
14. Sebaceous (oil) gland
15. Sweat Gland