1. Homeostatic Imbalances of Skin

3. Objectives I will be able to:
differentiate among first-, second-, third-, and fourth-degree burns.
explain the importance of the “rule of nines.”
summarize the characteristics of basal cell, carcinoma, Squamous cell carcinoma, and malignant melanoma.

4. Disorders of the Integumentary System
The skin can develop more than 1,000 different ailments.
The most common skin disorders include:
Infections and Allergies
Burns
Skin cancer

5. Infections and Allergies
Infections and allergies of the skin include:
Athlete’s foot – Tinea pedis fungal infection
Boils – inflammation of hair follicles
Carbuncles – clusters of boils often caused by Staphylococcus aureus
Cold sores – human herpesvirus 1 infection
Contact dermatitis – exposure to chemicals that provoke allergic responses (poison ivy, etc.)
Impetigo – lesions around the mouth and nose caused by highly contagious staphylococcus or streptococcus infections
Psoriasis – autoimmune disorder

6. Burns
burn: tissue damage resulting in cell death caused by electricity, chemicals, too much heat or UV radiation.
When skin is burned and cells destroyed, three life-threatening problems result:
loss of body fluids
dehydration and electrolyte imbalance leading to circulatory shock
infection

7. Burns Burns are classified according to severity/depth:
First degree – superficial epidermis: redness and swelling, not serious (e.g. sunburn)
Second degree – epidermis and upper dermis: blistering – semi-serious, regeneration of epithelium occurs
Third degree – full thickness: epidermis and dermis both destroyed – repaired with skin grafting
Fourth degree – full thickness: extend into muscle and/or bone – surgery, grafting, and/or amputation

9. Burns Lost fluids must be replaced immediately.
Volume of lost fluid can be estimated by the “rule of nines.”
rule of nines: method of computing the extent of burns by dividing the body into 11 areas, each accounting for 9% of the total body area plus 1% for the genital area.

10. Critical Burns
Critical burns require immediate medical attention and are potentially life threatening, disfiguring, and disabling.
Critical burn criteria:
Over 30% of the body has second-degree burns
Over 10% of the body has third-degree burns
Third-degree or fourth-degree burns on face, hands, feet, or genitals
Burns affect airway
Burns are circumferential (all the way around the body part)

11.  What are the three life-threatening consequences of a severe burn?
What are the criteria for classifying burns as first-, second-, third-, and fourth-degree?

12. Tumors of the Skin Tumors can be:
benign: a tumor that does not invade surrounding tissue or spread to other parts of the body; it is not a cancer
malignant: a cancerous tumor that is invasive and can spread to other parts of the body
Malignant or cancerous skin tumors are most often associated with overexposure to UV radiation.
metastasis: development of secondary malignant growths at a distance from a primary site of cancer
There are three common types of skin cancer.
Basal Cell Carcinoma – least malignant, prevent keratin formation in stratum basale and spread to epidermis and dermis. Slow-growing and easily cured through surgery.

13. Tumors of the Skin
Squamous Cell Carcinoma – arises in stratum spinosum, metastasizes to lymph nodes if not removed. Good chance of recovery if caught early.
Malignant Melanoma – arises in melanocytes and accounts for only 5% of skin cancers. Metastasizes rapidly to surrounding lymph and blood vessels. Only 50% chance of survival.
ABCDE Rule for recognizing melanoma:
Asymmetry – sides of spot don’t match
Border irregularity – edges of spot erratic
Color – spot contains different colors
Diameter – spot is larger than 6 mm
Evolution – A, B, C, or D is changing

15. Skin Cancer Sqaumous cell carcinoma Basal cell carcinoma
Malignant Melanoma

16.  What is the name of the rule for recognizing melanoma?
What is the most common risk factor for skin cancer?
Why don’t skin cancers develop in the stratum corneum?

17.  4 Corners You will count off and go to your assigned corner.
In your group, read the assigned question and discuss the possible answers.
Be prepared to share your group’s findings with the rest of the class. 11

18. 4 Corners Questions
You have just gotten a paper cut, but it doesn’t bleed. Discuss what layers of skin have been affected or not affected and be prepared to present to the whole class.
When Kyle caught his finger in a machine, the entire nail was torn off. Will his nail grow back? Discuss what conditions will affect potential regrowth and be prepared to present to the whole class.
Discuss how the color of your skin can affect your health if you spend a lot of time outside during the day. Be prepared to present to the whole class.
Discuss the reasons why middle-schoolers often have body odor while younger children do not. Be prepared to present to the whole class.

19. Web Links The Integumentary System, Part 1
The Integumentary System, Part 2
The Teenager With Butterfly Skin
What If You Stopped Showering for a Year?

20.  What are the four basic tissue types? Muscle tissue Nervous tissue
Epithelium – epidermis
Connective tissue - dermis

21.  What are the primary functions of skin?
What type of cell is most abundant in the epidermis?
In which epidermal layer do cells begin to die?
Which epidermal skin layer produces dandruff?
Which part of skin acts like a car radiator?
What pigments determine skin color?

22.  Why does skin color vary so much? How do fingerprints form?
Why do we leave behind fingerprints when we touch something?
Why do we have “heart lines” on the palms of our hands?

23.  Why do skin appendages extend down into the dermis?
Which of the cutaneous gland types can make your hair limp and oily?
What causes acne?
How do secretions of apocrine glands differ from eccrine gland secretions?
Which gland functions primarily for thermoregulation?
If you lose a fingernail, will it grow back?