Download LEARNING OBJECTIVE 1: Describe the four major types of

CHAPTER 6
SKIN AND THE INTEGUMENTARY SYSTEM
LEARNING OBJECTIVE 1: Describe the four major types of membranes.
Lecture Suggestions and Guidelines
1. Describe the structure and function of serous membranes. Include a definition, a summary of the types of tissue
which compose serous membranes, and examples of locations within the human body where serous membranes
are found.
2. Describe the structure and function of mucous membranes. Include a definition, a summary of the types of
tissue which compose mucous membranes, and examples of locations within the human body where mucous
membranes are found.
3. Describe the structure and function of synovial membranes. Include a definition, a summary of the types of
tissue which compose synovial membranes, and examples of locations within the human body where synovial
membranes are found.
4. Introduce the concept of skin as the cutaneous membrane.
Application Question(s)
1. Using wall charts, overheads, or anatomical models, ask students to identify the locations of and describe the
function of each major type of membrane, including serous, mucous, synovial, and cutaneous membranes.
Answer: Examples may include visceral/parietal peritoneum, visceral/parietal pleura, the hollow organs of the
digestive, respiratory, urinary, and reproductive tracts, the pericardium,, or joint cavities, etc.
Critical Thinking Issue(s)
1. The serous membranes (pleura), which line the lungs produce a slippery serous secretion. What is the function
of this secretion and what might be the consequences if the pleura secretes a deficient amount of serous fluid?
Excess?
Answer: If the pleural membranes secrete a deficient amount of serous fluid, the patient may experience
stabbing pains with each breath due to the friction of moving tissue resulting from dry, rough pleural surfaces.
This inflammation of the pleura is commonly called pleurisy. If the pleural membranes secrete an excess of
serous fluid, additional pressure is exerted on the lungs, which may also cause difficult breathing.
LEARNING OBJECTIVE 2: Describe the structure of the layers of the skin.
Lecture Suggestions and Guidelines
1. Discuss the structure of the epidermis. Include an introduction to stratified squamous epithelium, stratum
basale, stratum germinativum, stratum granulosum, stratum lucidum, and stratum corneum.
2. Describe the dermis as a layer of fibrous connective tissue, which contains muscle fibers, blood vessels, and
nerve fibers. Include an introduction to the papillary layer and reticular layer.
3. Describe the subcutaneous layer, which is composed of loose connective tissue and adipose tissue.
Application Question(s)
1. Ask each student to develop a list of all the functions of the skin with which they are familiar. Once this list is
completed, have them describe how each function is accomplished. Ask for specific examples.
Answer: Functions which should be included on the list: protection from mechanical damage, chemical
damage, bacterial damage, UV radiation, extreme heat, extreme cold, and extreme dryness. The skin also plays
a role in excretion and the synthesis of vitamin D. Many kinds of sensory receptors are located in the skin.
Students should give specific examples of how each function is accomplished. For example, it was previously
mentioned that skin plays a role in excretion. This is accomplished through perspiration produced by sweat
glands which contains nitrogenous waste products such as urea and uric acid.
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Critical Thinking Issue(s)
1. How is the Rule of Nines used to assess the extent of skin damage caused by burns?
Answer: The body is divided into eleven (not nine!) major regions. Each region accounts for approximately
nine percent of the body’s total surface area. A breakdown of each area is as follows: a) anterior head and neck4.5%; b) posterior head and neck-4.5%; c) anterior upper limbs-9%; d) posterior upper limbs-9%; e) anterior
lower limbs-18%; f) posterior lower limbs-18%; g) anterior trunk-18%; h) posterior trunk-18%; and i)
perineum-1%.
LEARNING OBJECTIVE 3: List the general functions of each layer of the skin.
Lecture Suggestions and Guidelines
1. Discuss the functions of the skin, including protection from mechanical injury, chemical damage, bacterial
agents, UV radiation, thermal damage and dessication. Include a discussion of how the skin assists in excretion
of nitrogenous wastes and the synthesis of vitamin D.
2. Discuss how the dermis supplies nutrients to skin cells, helps regulate body temperature, and carries impulses
to muscles and glands of the skin through dermal nerve fibers.
3. Describe the role of the subcutaneous layer in terms of the conservation of body heat and the supply of blood
through vessels to the skin.
Application Question(s)
1. Ask students to discuss the irony of the statement “Beauty is only skin deep” in light of the information learned
in this chapter.
Answer: The statement is ironic in the fact that the stratum corneum, the outermost layer of skin which we see,
is composed of dead cells which are replaced approximately once a month.
Critical Thinking Issue(s)
1. Discuss why dermal papillae found in the papillary layer of the dermis are of significance in forensic medicine.
Answer: The patterns of dermal papillae are genetically determined. No two patterns are exactly the same. The
combination of unique papillary patterns with secretions of perspiration leave identifiable and traceable
signatures called fingerprints.
LEARNING OBJECTIVE 4: Describe the accessory organs associated with the skin.
and
LEARNING OBJECTIVE 5: Explain the functions of each accessory organ.
Lecture Suggestions and Guidelines
1. Describe the cutaneous glands, including sebaceous glands, sudoriferous glands, eccrine glands, and apocrine
glands.
2. Discuss hair and hair follicles. Introduce the terms root, shaft, hair bulb, medulla, cortex, and arrector pili.
3. Introduce nails as modifications of epidermal tissue that has undergone keratinization.
4. Describe the function of sebaceous glands and the production of sebum.
5. Discuss the role of two types of sudoriferous glands; eccrine glands and apocrine glands.
6. Give examples of the protective function of hair.
7. Introduce the role of nails in humans.
Application Question(s)
1. What causes “split ends?”
Answer: The cuticle, which surrounds the cortex and medulla of each hair, is subject to friction and abrasion.
Excess wear and tear on the cuticle will cause it to erode, exposing the keratin fibers of the inner hair region,
causing the hair to frizz.
Critical Thinking Issue(s)
1. Discuss examples of metabolic disorders involving the accessory organs of the skin.
Answer: Metabolic disorders of the accessory organs often involve hyperactivity of the sebaceous glands or
excessive production of keratinocytes. Examples include: a) acne-predominant at puberty due to estrogen and
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testosterone stimulation of glandular activity causing sebum production to increase; b) seborrheic dermatitisexcessive secretion of sebum from the sebaceous glands, resulting in oily scalp and formation of scales of
dandruff; c) sebaceous cysts-form when a sebaceous gland duct becomes blocked with sebum; d) seborrheic
keratosis-over-proliferation of keratinocytes, producing raised, seely lesions occurring with aging; and e)
psoriasis-lesions of red patches with sharply marked edges, covered with white or silvery scales. Psoriasis is of
a hereditary origin, but the precise cause is unknown.
LEARNING OBJECTIVE 6: Explain how the skin helps regulate body temperature.
Lecture Suggestions and Guidelines
1. Explain the importance of body temperature regulation as it affects homeostasis and the rates of metabolic
reactions.
2. Introduce the concept of heat production and loss. Include the terms radiation, conduction, convection,
evaporation, and cellular respiration.
3. Discuss the causes and effects of hypothermia.
Application Question(s)
1. During the Cotton Bowl football game in 1979, a report was issued from the sideline that Joe Montana, the
Notre Dame quarterback, was suffering from extreme hypothermia, and would most likely not be able to return
to the game. What is hypothermia? Explain the mechanism employed by the body to return the patient to
homeostasis.
Answer: Hypothermia stems from lowered body temperature. In Montana’s case, he had become extremely
chilled due to weather conditions, as well as from the initial onset of flu-like symptoms. The hypothalamus
senses the drop in body temperature and signals the nervous system to cause dermal blood vessels to constrict,
sweat glands to remain inactive, and muscles to contract involuntarily. Muscle activity generates body heat,
which causes body temperature to rise toward normal. (In addition, Joe Montana was bundled in blankets and
fed hot chicken noodle soup in the locker room. Dramatically, he returned late in the game to overcome a 34-12
deficit, and lead Notre Dame to victory in the final seconds of the game.)
Critical Thinking Issue(s)
1. Discuss cases in which hypothermia may be intentionally induced.
Answer: Hypothermia may be intentionally induced during certain surgical procedures. For example, during
surgical repair of a dysfunctional heart valve, such as mitral valve prolapse, the heart can be chilled to greatly
reduce its pumping activity. This temporary form of hypothermia allows the surgeon access to the valve by
effectively slowing the heart’s activity by employing medications and ice.
LEARNING OBJECTIVE 7: Summarize the factors that determine skin color.
Lecture Suggestions and Guidelines
1. Introduce the term melanin.
2. Discuss genetic factors, environmental factors, and physiological factors, which may influence skin color.
3. Introduce basic clinical terminology such as cyanosis, erythema, jaundice, and pallor.
Application Question(s)
1. How does “tanning” occur?
Answer: The color of skin is determined, in part, by the amount of melanin produced by melanocytes in the
stratum basale. Sunlight stimulates the melanocytes to produce increased amounts of the melanin pigment,
which darkens the skin.
Critical Thinking Issue(s)
1. Briefly discuss a variety of neoplastic skin diseases.
Answer: Examples of neoplastic skin disease include a) Nevus (mole)-benign tumor of melanocytes, b) Basal
Cell Carcinoma-most common skin cancer, non-metastasizing, but somewhat invasive; slow growing, c)
Squamous Cell Carcinoma-a keratinocyte tumor, invasive, may metastasize, faster growth than basal cell
carcinoma, may move through lymph; and d) Malignant Melanoma-most serious skin cancer, arises form the
melanocytes of the epidermis, a tumor of melanocytes, highly malignant, metastasizes early and rapidly.
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RELATED DISEASES OF HOMEOSTATIC INSTABILITY
1. Impetigo—Caused by the spread of Staphylococcus or Streptococcus to the face and hands. Typical signs are
erythema, vesicles, pustules, fever, and enlarged lymph nodes.
2. Erysipelas—Streptococcus infection spread from a respiratory discharge to the skin that may enter a surgical
incision or wound. The patient may experience sudden fever and chills, and typical inflammatory symptoms.
3. Urticaria—Commonly known as hives; a vascular reaction to an allergen. May exhibit wheals, which are round,
red-rimmed lesions with pale centers. Usually extremely pruritic.
SUGGESTIONS FOR ADDITIONAL READING
Aulas, Jean-Jacques. September 1996. Alternative Cancer Treatments. Scientific American.
Brash, Douglas E., and David J. Leffell. July 1996. Sunlight and Skin Cancer. Scientific American.
Ceballos, P.I., R. Ruiz-Maldonado, and M.C. Mihm, Jr. March 9, 1995. Current concepts: Melanoma in children.
New England Journal of Medicine, vol. 332. It is rare, but children can be born with this serious skin cancer all
over their bodies.
Kamb, Alexanber. December 22, 1994. Sun protection factor p. 53. Nature, vol. 372. Peeling skin after a sunburn is
a protective mechanism to shed damaged cells that might otherwise proliferate.
Marks, Jonathon. December 1994. Black, white, other. Natural History. Race as a cultural designation has little, if
anything, to do with biology.
Morganthau, Tom. February 13, 1995. What color is black? Newsweek. Defining race by a single trait—skin color—
makes no biological sense.
Murray, Charles and Richard Herrnstein. 1994. The Bell Curve: Intelligence and Class Structure in American Life.
The Free Press. A highly controversial book proposing, among other things, that it’s almost impossible to alter
intelligence, and that we shouldn’t attempt to do so through social programs to help the disadvantaged.
Wills, Christopher. November 1994. The skin we’re in. Discover. We humans are mesmerized by melanin, the
pigment that gives color to our skin, but almost always for quite the wrong reason.
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