ch. 4 continued skin structures and homeostatic imbalances
TRANSCRIPT
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Ch. 4 Continued
Skin Structures and Homeostatic Imbalances
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Skin StructureSkin Structure
Slide 4.10a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Epidermis – outer layer
Stratified squamous epithelium
Often keratinized (hardened by keratin)
Dermis
Dense connective tissue
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Skin StructureSkin Structure
Slide 4.10b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Underneath the dermis is the hypodermis
Not part of the skin
Anchors skin to underlying organs
Composed mostly of adipose tissue
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Layer of EpidermisLayer of Epidermis
Slide 4.11a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Stratum corneum (Top Layer)
Shingle-like dead cells
Stratum lucidum (under stratum corneum)
Occurs only in thick skin (palms of hands and soles of feet)
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Layer of EpidermisLayer of Epidermis
Slide 4.11b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Stratum granulosum (under stratum lucidium or stratum corneum)
Stratum spinosum (under stratum granulosum)
Stratum Basale (under stratum spinosum)
Cells undergoing mitosis
Lies next to dermis
Location of most melanin (pigment)
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Skin Layers
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MelaninMelanin
Slide 4.12Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Pigment (melanin) produced by melanocytes
Color is yellow to brown to black
Melanocytes are mostly in the stratum basale
Amount of melanin produced depends upon genetics and exposure to sunlight
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Freckles
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DermisDermis
Slide 4.13a
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Two layersPapillary layer (upper layer)
Projections called dermal papillae Pain receptors Capillary loops
Reticular layer (bottom layer) Blood vessels Glands Nerve receptors
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Normal Skin Color DeterminantsNormal Skin Color Determinants
Slide 4.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Melanin Yellow, brown or black pigments
Carotene Orange-yellow pigment from some
vegetables
Hemoglobin Red coloring from blood cells in dermis
capillaries
Oxygen content determines the extent of red coloring
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Exocrine Glands Exocrine Glands (Cutaneous Glands)(Cutaneous Glands)
Slide 4.15Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sebaceous glands
Produce oil
Lubricant for skin
Kills bacteria
Most with ducts that empty into hair follicles
Glands are activated at puberty
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Where are the Sebaceous Glands?
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Appendages of the SkinAppendages of the Skin
Slide 4.16Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Sweat glands
Widely distributed in skin
Two types
Eccrine
Open via duct to pore on skin surface
Apocrine
Ducts empty into hair follicles
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Where are the Sweat Glands?
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Sweat and Its FunctionSweat and Its Function
Slide 4.17Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Composition Mostly water Some metabolic waste Fatty acids and proteins (apocrine only)
Function Helps dissipate excess heat Excretes waste products Acidic nature inhibits bacteria growth
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Appendages of the SkinAppendages of the Skin
Slide 4.18Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Hair
Produced by hair follicle
Consists of hard keratinized epithelial cells
Melanocytes provide pigment for hair color Figure 4.7c
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Associated Hair StructuresAssociated Hair Structures
Slide 4.20Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Hair follicle
Dermal and epidermal sheath surrounding hair root
Arrector pilli
Smooth muscle
Sebaceous gland
Sweat gland Figure 4.7a
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Appendages of the Skin
Nails Scale-like modifications of the epidermis
Heavily keratinized
Stratum basale extends beneath the nail bed
Responsible for growth
Lack of pigment makes them colorless
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Nail Structures
Free edge
Body
Root of nail
Eponychium – proximal nail fold that projects onto the nail body
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Quick Quiz!Quick Quiz!
Slide 4.14Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
On what layer of the epidermis does mitosis occur?
What two types of glands make up the exocrine glands?
What causes “goose bumps” on the skin?
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Skin Homeostatic ImbalancesSkin Homeostatic Imbalances
Slide 4.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Infections and Allergies Athletes foot
Caused by fungal infection
Boils and carbuncles
Caused by bacterial infection
Cold sores
Caused by virus
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Skin Homeostatic ImbalancesSkin Homeostatic Imbalances
Slide 4.24Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Infections and allergies Contact dermatitis
Exposures cause allergic reaction
Impetigo
Caused by bacterial infection
Psoriasis
Cause is unknown
Triggered by trauma, infection, stress
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Skin Homeostatic ImbalancesSkin Homeostatic Imbalances
Slide 4.25Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Burns
Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals
Associated dangers
Dehydration
Electrolyte imbalance
Circulatory shock
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Rule of NinesRule of Nines Slide 4.26
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Way to determine the extent of burns
Body is divided into 11 areas for quick estimation
Each area represents about 9%
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Severity of BurnsSeverity of Burns
Slide 4.27Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
First-degree burns Only epidermis is damaged Skin is red and swollen
Second degree burns Epidermis and upper dermis are damaged Skin is red with blisters
Third-degree burns Destroys entire skin layer Burn is gray-white or black
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Critical BurnsCritical Burns
Slide 4.28Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Burns are considered critical if:
Over 25% of body has second degree burns
Over 10% of the body has third degree burns
There are third degree burns of the face, hands, or feet
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Skin CancerSkin Cancer
Slide 4.29Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cancer – abnormal cell mass
Two types Benign
Does not spread (encapsulated)
Malignant
Metastasized (moves) to other parts of the body
Skin cancer is the most common type of cancer
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Skin Cancer TypesSkin Cancer Types
Slide 4.30Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Basal cell carcinoma Least malignant
Most common type
Arises from statum basale
Squamous cell carcinoma Arises from stratum spinosum
Metastasizes to lymph nodes
Early removal allows a good chance of cure
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Squamous Cell Carcinoma
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Skin Cancer TypesSkin Cancer Types
Slide 4.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Malignant melanoma Most deadly of skin cancers
Cancer of melanocytes
Metastasizes rapidly to lymph and blood vessels
Detection uses ABCD rule
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ABCD RuleABCD Rule
Slide 4.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
A = Asymmetry Two sides of pigmented mole do not match
B = Border irregularity Borders of mole are not smooth
C = Color Different colors in pigmented area
D = Diameter Spot is larger then 6 mm in diameter
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Quick Quiz!
• What are the three types of burns?
• How is the extent of burns calculated?
• Name one type of skin cancer.