INTEGUMENTARY SYSTEM
The skin is the largest
organ.
Skin Functions
• Physical barrier
• General senses: touch,
pressure, pain, temperature
• Vitamin D source
• Temperature regulation
• Excretion of wastes
Types of cells:
• Keratinocytes
– produce keratin
– totally replaces epidermis every 25-45 days
• Melanocytes
– produce melanin
• Langerhans
– dermal macrophages
• Merkel cells
– sensory receptors for touch
Skin Layers
• Epidermis - Stratified squamous
epithelium that is keratinized
• Dermis - Irregular dense fibrous
connective tissue
Major Layers of Skin
• Epidermis
– stratum corneum
• outermost
• thickest
• dead, flaky, dandruff
– stratum lucidum
• (clear)
– stratum granulosum
• increased keratinization
Major Layers of Skin
• Epidermis
–stratum spinosum
• (prickly layer)
–stratum basale
• (stratum
germinativum)
• mitotic division
• Contains
melanocytes
Skin Layers
• Dermis
– Papillary layer contains:
• Dermal papillae
• Meissner’s corpuscles (touch receptors)
– Reticular layer
• Arteries
• Veins
• Glands
• Pacinian corpuscles (pressure receptors)
Skin Color
• Melanin
– Yellowish to reddish-brown to black
– Racial differences result from kind and
amount of melanin
– Freckles: local accumulation of melanin
– Melanin increase due to damage from
ultraviolet radiation
• Excessive exposure to sun damages elastin
fibers, depresses immune system, and alters
DNA possibly leading to skin cancer
• Carotene
– Yellowish, orange
– Accumulation due to diet
• Hemoglobin - reddish
Color variations
– Redness (Erythema)
• blushing, fever, inflammation, allergy
– Pallor
• fear, anger, stress, anemia
– Jaundice
• yellowish color due to bile; liver disorder
– Bronzing
• Addison’s disease ; adrenal cortex disorder
– Bruises (hematoma)
• clotted blood beneath skin
Accessory Structures
• Sudoriferous (Sweat) Glands
–Eccrine glands
• covers most of body; especially
hands, feet, and head
• Eccrine secretion contains water,
salts, vitamin C, antibodies, waste
(urea, uric acid, ammonia), and
lactic acid
Accessory Structures
• Sudoriferous (Sweat) Glands
–Apocrine glands (axial and genital
areas)
• Apocrine secretions add fatty substances
and proteins
• Breakdown of aprocrine secretions by
bacteria causes body odor
• Begin functioning at puberty
Accessory Structures
• Specialized
Sudoriferous
(Sweat) Glands
–Ceruminous
glands - secrete
wax
–Mammary glands
- secrete milk
instead of sweat
• Sebaceous (Oil) Glands
– Secrete sebum
• softens and lubricates skin and hair
• waterproofs
• activated by hormones during puberty
– Whitehead - gland blocked by accumulated
sebum
– Blackhead - dried, oxidized sebum
– Acne - active inflammation of sebaceous glands
– Seborrhea (Cradle cap) - overactive sebaceous
glands
Hair & Hair Follicles
– Structure of hair
• Shaft - projects from
skin
• Root - embedded in
skin
• 3 layers of ketatinized
cells
– medulla - core
– cortex - surrounds core
– cuticle - outermost
layer
Hair & Hair Follicles
– Structure of follicle
• Hair bulb - expanded end of follicle
• Hair papilla - dermal papilla protruding into
hair bulb; supplies nutrients; stimulates
growth
• Hair matrix - produces hair; active division;
older cells pushed to top, increase
keratinization & die
• Arrector pili -muscle that raises hairs;
causes goose bumps
Distribution, Types, & Growth of Hair
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Vellus - fine body hair of children and females
Terminal - coarse hair of scalp and eyebrows
Growth stimulated by androgens
Affected by nutrition
Average growth rate = 2mm per week
Hair Cycles vary
– scalp follicles active approx. 4 yrs
– eyebrow follicles active 3-4 months
Hair Thinning & Baldness
–After 40’s resting cycles lengthen
–Hair not replaced as fast as lost
–Baldness = alopecia
• Male Pattern Baldness
–Genetically determined
–Sex influenced
Nails
• Scale-like modifications of epidermis
• Structure
– Free Edge
– Body
– Root
– Nail Bed - epidermis beneath nail body
– Nail Matrix - proximal portion of nail
bed
– Lunula
– Nail folds
– Eponychium (cuticle)
Skin Disorders
• Warts - nonmalignant epithelial growth caused by a
virus
• Cold sores (fever blisters)
– small fluid-filled blisters around lips & mouth
– caused by a herpes simplex virus
• Acne - inflammation of sebaceous glands
• Impetigo - inflamed lesions caused by staphylococcus
infection
• Decubitus ulcers (bed sores) caused by irritation and
inadequate circulation
Skin cancers
• Most skin tumors benign (ex. Warts)
• Basal Cell Carcinoma
– least malignant
– approx. 30% of caucasians will develop this
– 99% cure rate
• Squamous Cell Carcinoma
– Scaly elevation arising from the stratum
spinosum
Cutaneous melanoma
• Arise from melanocytes
• 2 types
– melanocarcinoma
– malignant melanoma
• Irregular growths with variety of pigmentation (brown,
gray, black, or blue)
• Occur in all age groups, usually in people who
sunburn easily
• More common in people who get short intense
exposure to sunlight.
• Survival rate is low.
• May begin in regular skin or mole
ABCDE rule
–A - Asymmetry
–B - Border irregularity
–C - Color
–D - Diameter
–E - Elevation
ABCD’s of Skin Cancer
Classification of Burns
• First-degree burns - involves only epidermis
• Second-degree burns - involves both
epidermis and dermis
• Third-degree burns - complete destruction of
both layers, probable involvement of
subcutaneous tissue
• Burns also classified by the extent of burn
area
Classification of Burns
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RULE of NINES
Head = 9%
Anterior Thoracic = 9%
Posterior Thoracic = 9%
Anterior Abdomen = 9%
Posterior Abdomen = 9%
Left Arm = 9%
Right Arm = 9%
Anterior Left Leg = 9%
Posterior Left Leg = 9%
Anterior Right Leg = 9%
Posterior Right Leg = 9%
Genitals = 1%