Ex:7 Skin and Membrane

I. Introduction/Background Information

1. To recount several important functions of the skin, or integumentary system.
2. To recognize and name from observation of an appropriate model, diagram projected slide, or microscope examination the following skin structures:

• epidermis (including strata)
• dermins (papillary and reticular layers
• hair follicles and hair
• sebaceous glands and sweat gland

    3. To compare the properties of the dermis and epidermis.
    4. To describe the distribution and function of the skin derivaties, sebaceous glands, sweat glands and hair.
    5. To differentiate between eccrine and aprocrine sweat glands.
    6. To enumerate the factors determining skin color.
    7. To describe the function of melanin
    8. To compare the structure and function of the major membrane types, epithelial and synovial
    9. To list the general functions of each membrane type and note its location in the body.
   10. To recognize by microscope examination epidermal, mucous, and serous membrane.

II. Hypothesis

Part 1: Basic structure of the skin: If students read about structures as they locate them on a skin model then they will be able to write out a response to each objective
Part 2: Appendages of the Skin: If students examine a prepared slide of human skin then they will be able to identify skin structures on a drawing.
Part 3: Plotting the Distribution of sweat glands: If bond paper is taped to skin coated with iodine and left for 20 minutes, then a distribution of sweat glands will be mapped out because the sweat glands will dissolve the iodine, which will then be absorbed by the paper.  As it reacts with the starch in the bond paper each sweat gland will produce a blue/black dot.
Part 4: Classification of Membranes: If students examine slides from trachea and small intestine, heart, as well as a freshly cut joint, then they can compare mucous, serous and synovial membranes.

III.  Materials

• Skin model
• Compound microscope
• Prepared slide of human skin with hair follicles
• Sheet of #20 bond paper ruled to mark off cm2 areas
• Scissors
• Betadine swabs, or Lugol's iodine and cotton swabs
• Adhesive tape
• Prepared slide of trachea (cross section) and small intestine (cross section)
• Prepared slide of serous membrane (e.g. mesentery)
• Longitudinally cut fresh beef joint (if available) 

IV. Procedure

“See Lab Instructions” (you may include pictures of procedure)

Part 1: Basic structure of the skin:

Skin slide

Human Skin Slide

Part 2: Appendages of the Skin:
Part 3: Plotting the Distribution of sweat glands:
Part 4: Classification of Membranes:

pseudostratified ciliated columnar epithelium

mucosa of trachea

mucosa of small intestine

drawing of one villus

pericardium (around the heart)

V. Results/Observation. Data

 List answers to questions from each section of the lab
Part 1: Basic Structure of the skin
Part 2: Appendages of the skin:
How is this stratified squamous epithelium different from the observed in Exercise 6? More detail and shows accessory features.

How do these differences relate to the functions of these two similar epithelial? Controls the body's heat by either insulating heat or sweating.

Part 3: Plotting the Distribution of sweat glands:
Which skin area tested has the greater density of sweat glands? Palm

Labeled Pictures:
Part 4: Classification of Membranes:
Which of these mucous membranes contains goblet cells? Intestinal
How do the roles of these two mucous membranes differ?The Trachea is part of the respiratory system and is made up of pseudostratified ciliated columnar epithelium, while the small intestine is part of the digestive system and is made of up simple conciliated columnar epithelium.
How are they the same? They both secrete mucus and are "wet" membranes that are constantly bathed in secretions.
Would you say that mucous membranes have a high regenerative capacity? Why or why not? I think that they do have a high regenerative capacity because they are made up epithelium cells and as long as they get the right amount of oxygen they can duplicate themselves.
What kind of cells that you have seen many times before are these shaped like? Simple Squamous Epithelium
What are the specific names of the serous membranes covering the heart and lining the cavity in which it requires (respectively)? Pericardium
The lungs and thoracic cavity (respectively)? Pleura
The abdominal viscera and visceral cavity (respectively)?Peritoneum

Synovial membrane

VI. Conclusion: Respond to each objective. What did you learn?

1.  What are the important functions of the skin/integumentary system? To protect from damages, insluate the body, prevent water loss, and to cushion the body tissues.
2. Can you recognize and name the following structures from a slide, model or diagram? With some more studying, yes.
• epidermis (including strata), 
• dermis (papillary & reticular layers
• hair follicles & hair
• sebaceous glands & sweat glands
3. Compare the properties of the dermis & epidermis. The epidermis is made up of stratifed squamous epithelium that is able to keratinize. (become hard an tough). The dermis is benethe the epidermis and is made up of mostly connective tissues.
4. Describe the distribution and function of the sebaceous glands, sweat glands, and hair.
   Sebacceous glands (oil glands): found all over the skin, except the palms of hands and soles of feet. A prouduct of sebaceous glands is sebum, which keeps the skin soft and moist and prevents the hairs on the kinds from becoming brittle.
   Sweat Glands: widley distrivuted in the skin. 2 types of sweat glands, eccrine and apocrine
   Hair: All over the body, has minor protection functions, provides some insulation from the cold weather.
5. Differentiate between eccrine & apocrine sweat glands. Eccrine galnds are more numerous and found all over the body. These glands are very imporatnt when regulating tthe bodys head. They are supplied with nerve endings that cause them to secrete sweat when the external temperature is too high. The apocrine sweat glads are confined to the axillary and genital areas of the body. The are larger in size than the eccrine glands and their ducts empty into hair follicles. The secretions contain fatty acids and proteins and the color is milkly or yellowish.
6. Ennumerate the factors determining skin color. Melanin and sunlight.
7. Describe the function of melanin. Melanin is a pigment that makes of the skin, which ranges from yellow to brown to balck. The cells are called melanocytes found in the stratum basale. When the melanin is explose to the sunlight the melanocytes become more active which causes tanning of the skin.
8. Compare the structure and function of the major membrane types.
   Cutaneous: epithelial tissue, absorption and secretion (keeps skin soft and moist)
   Mucous: epithelial tissue, secreates (prevents friction)
   Serous: epithelial tissue, prevents body from drying out
   Synovial: connective tissue, secreates & lines cavities around joings
9. List the general functions of each membrane type and note its location in the body
   Cutaneous: absorption & secretion, all over the skin, except for palms of ands and soles of feet. Also in the hair follicles
   Mucous: Secreates, on loose connective tissue, line body cavities
   Serous: Secreates, line body cavities, skin
   Synovial: Secreates, between joints
10. Can you recognize by microscopic examination epidermal, mucous, and serous membranes? Maybe, if i get to see them under a microscope.