Download Lecture Suggestions and Guidelines

CHAPTER 6
INTEGUMENTARY SYSTEM
LEARNING OBJECTIVE 1: 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.
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 neck—4.5%; 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 2: 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 3: Describe the accessory organs associated with the skin.
and
LEARNING OBJECTIVE 4: Explain the functions of each accessory structure of the
skin.
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 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 5: 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 6: 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, nonmetastasizing, 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 from the melanocytes of the epidermis, a tumor of
melanocytes, highly malignant, metastasizes early and rapidly.
LEARNING OBJECTIVE 7: Describe the events that are part of wound healing.
Lecture Suggestions and Guidelines
1. Review the signs and symptoms of inflammation.
2. Compare the healing processes in various layers of the skin.
3. Discuss the major types of burns.
Application Question(s)
1. Ask students to estimate damage to the integument by utilizing the “rules of
nines”.
Answer: Each of the eleven sections of the body account for nine percent of the
total area.
Critical Thinking Issue(s)
1. Provide students with a field trip experience to a local hospital’s burn unit. Ask
them to prepare a short essay regarding their observations.
Answer: Responses will vary.
LEARNING OBJECTIVE 8: Describe life-span changes in the integumentary system.
Lecture Suggestions and Guidelines
1. Introduce the phenomena of age spots, wrinkling and sagging.
2. Explain why elderly people are less able to tolerate conditions of extreme heat
and cold.
3. Discuss the effects of aging on the activation of vitamin D.
Application Question(s)
1. Ask students to interconnect changes in the integument and changes in other
organ systems during the aging process.
Answer: Discussion should include interaction with all other major organ
systems.
Critical Thinking Issue(s)
1. Ask students to interview a variety of elderly people as to the effects the
interviewee has noticed on the integumentary system during aging.
Answer: Responses will vary.
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.
Seppa, Nathan. January 4, 2003. Clear Skin – Injections counteract psoriasis in patients.
Science News.
Travis, John. August 19, 2000. Skin cells reveal they have hairy origins. Science News,
vol. 158, no. 8, pg. 118.
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.