Download - Skin and the Integumentary System
Skin and the Integumentary System
Chapter 6
Functions of the Skin
Maintain homeostasis Protective covering Contains immune cells Synthesizes vitamin D Excretes wastes Slows water loss Regulates body temp Houses sensory receptors
Layers of Skin 3 layers:
Epidermis ▪ Outer layer
Dermis ▪ Inner layer
Subcutaneous ▪ Hypodermis layer
Cut-, skinDerm-, skinEpi-, uponHypo-, below
Epidermis Thickest on palms and
soles 0.8-1.4mm
Accessory structures Hair follicles Nails
Melanocytes Provide melanin
Epidermis Composed of stratified squamous epithelium Keratinized
Cells synthesize keratin packed cells Separated from dermis by basement membrane Lacks blood supply
Layers of Epidermis Stratum corneum
corneum = horn (Latin) Outer keratinized layer,
dead Desquamation
Stratum lucidum lucid = clear (Latin) Palms, soles
Stratum granulosum granulose = granular
(Latin) Flat, granular (keratohyalin)
Layers of Epidermis
Stratum spinosum Spiny, prickly Dividing, melanocyte branches
Stratum basale (germinativum) Basal = basement, bottom layer Melanocytes, dividing, deepest layer
Dermis Bind epidermis to underlying
tissue Irregular dense CT Muscle fibers
Smooth & skeletal Dermal papillae
Increased surface area to nourish epidermis
Fingerprints Friction for gripping
Average thickness 1.0-2.0mm
Dermis Accessory structures
Nerve cell processes▪ Pacinian (heavy
touch/pressure)▪ Meissner’s (light
touch/pressure)▪ Free nerve endings
(temperature, pain) Blood vessels Sweat glands
Subcutaneous Layer “Hypodermis” Loose CT & adipose
tissue Major blood vessels Insulation
Hair Follicles From epidermal cells Extends into dermis
Contains hair root Hair color
Melanin production▪ Albinism
Arrector pili muscle Smooth muscle Attaches to each
follicle▪ Autonomic innervation
Hair Growth Cyclic growth
Formed by cells in follicle
Keratinize and die Form hair shaft
Type of hair Eyelash
▪ Grow 30 days, 100 days rest
Scalp▪ Grow 3-6 years, rest few
months▪ 0.3 mm/day
Sebaceous Glands Associate with hair
follicles Absent on palms and
soles Holocrine glands
Release entire cells Secrete sebum
Mixture of fatty acids and cellular debris
Secreted into hair follicle
Excess sebum acne
Seb-, grease
Clinical Application Acne
Disorder of sebaceous glands
Hormonally influenced At puberty Adrenals androgens Stimulates sebum
production
Clogged gland Excess sebum, epithelial
cells Blackheads & whiteheads Good environment for
anaerobic bacteria
Clinical Application Immune system triggers inflammation
Pimple Treatment options
Antibiotics Estrogen Retinoic acid (Vitamin A derivatives)
▪ Accutane
Nails Protective coverings on fingers,
toes Made of:
Nail plate Nail bed (skin) Lunula
▪ White region▪ Half-moon shape▪ Active in growth
Reflection of health status Blue = cyanosis; white = anemia;
pigment = injury or melanoma; depressions/furrows = anemia, malnourishment; red streaks = ulcers, hypertension, RA
Growth rate 0.5-1.2 mm/day
Sweat Glands Sudoriferous glands
Widespread in skin▪ Deep dermis or
subcutaneous layer Eccrine glands
Most numerous Apocrine glands
Active in puberty Modified sweat
glands Ceruminous Mammary
Sweat Glands Eccrine glands
Most numerous Response to
▪ High temp▪ Exercise▪ Stress (on hands)
Open as pore▪ Forehead, neck, back
Sweat Glands Apocrine glands
Onset @ puberty Response to
▪ Fear▪ Pain▪ Distress
Open into hair follicle▪ Armpit▪ Groin
Odor▪ Bacterial metabolism
of secretions
Sym
path
etic
resp
onse
Sweat
Water Salts
Sodium Chloride Potassium Magnesium
Wastes Urea Lactate
Regulation of Body Temp Heat
Product of cellular metabolism
Active cells are major heat producers Skeletal muscle
As body temp , body releases heat
Homeostasis Maintain body temp at
37C or 98.6 F
Releasing Body Heat Radiation (2)*
Most of heat loss Infrared heat rays escape from
warmer to cooler surroundings Evaporation (5)*
At high temp, eccrine sweat glands release sweat onto skin
Heat carried away as skin cools Conduction
Heat transferred from body directly to cooler object
Ex. Cold car seats Convection (4)
Warm air circulates away from body
Conserving Body Heat Dermal blood
vessels Reduce heat-carrying
blood thru skin Muscle activity
Increased cell respiration ▪ Heat production
Shivering▪ Small groups of
muscles contract▪ Produce heat
Problems in Body Temp Regulation Hyperthermia
Abnormally high Humid air prevents
evaporation of sweat▪ No cooling
High air temp reduces radiation cooling
Hypothermia Abnormally low Shivering mental
confusion, lethargy, loss of reflexes, shut down of major organs▪ Some surgeries
(heart, brain) require body to be cooled less oxygen is required
Skin Color
Genetic Factors Melanocytes
▪ Same # in all people Melanin production
▪ Varies by person Melanin production
▪ High darker skin▪ Low fairer skin
Albinism▪ No melanin
Environmental factors Darken existing
melanin Stimulate
production▪ Sunlight▪ UV light from
▪ Sunlamps▪ X rays
Tans fade▪ Pigmented epidermal
cells keratinize ▪ Wear away
Skin Color Physiological Factors
Blood vessels in dermis adds color▪ Content of vessels
▪ High oxygen hemoglobin is bright red Pinkish hue to skin
▪ Low oxygen hemoglobin is dark red Bluish hue to skin (cyanosis)
▪ State of vessels▪ Dilation skin reddens▪ Constriction skin pales
Dietary influences Carotene yellow/orange skin tone
Health influences Jaundice yellowish skin (liver)
Healing of Wounds and Burns Inflammation
Response to injury or stress Healing events depend on nature of
injury Cuts
Shallow ▪ Epithelial cells divide fill in gap
Deep cut ▪ Blood vessels break blood clot
Healing of Wounds and Burns Clot
Scab formation▪ Fibrin, blood cells,
platelets, fluids Fibroblasts
Secrete collagen ▪ Binds wound together
Scar Extensive wound Connective tissue
on skin surface
Burns First degree
Superficial partial thickness▪ Injuring epidermis only▪ Healing in 2-3 days
Common examples▪ Sunburn▪ Scalding water▪ Chemicals
Treatment▪ Flush with cool water (no ice)▪ Aloe (no oil)▪ Clean, dry bandage
Burns Second degree
Deep partial thickness▪ Injures epidermis and dermis▪ Fluid escapes capillaries blisters▪ Healing time 1-2 weeks
Common examples▪ Prolonged sunburn or scalding water▪ Brief exposure to flame
Treatment▪ Flush with water, bandage▪ Do NOT break blisters▪ > 2-3 inches, see physician
▪ Hydration▪ Antibiotics▪ Grafting
Burns Third degree
Full-thickness▪ Epidermis, dermis, accessory
organs▪ Healing time: weeks to months
Common examples▪ Contact with flame▪ Corrosive chemicals▪ Immersion in hot liquids
Treatment▪ Burn center▪ Debridement▪ Grafting
Grafting Autograft
“Auto” self▪ Remove skin from unburned part of body and “transplant” it to
injured site Homograft
“Homo” like▪ Cadaveric skin used if can’t do autograft
Skin substitutes Amniotic membrane Artificial membrane Cultured epithelial cells
Scarring
Healing of Burns
Treatment of patient: Requires estimate
of body surface injury▪ Replace body fluids
and electrolytes▪ Determine amount of
skin needed for graft Use “rule of nines”
▪ Divide skin surface into regions
▪ Each region = 9% (or multiple of 9%)
Life Span ChangesAging skin shows many signs…
Cell cycle slows Age (liver) spots Dermis reduced
Connective tissue growth slows ▪ Slower wound healing
Loss of fat▪ Wrinkles & sagging skin
Melanin production slows Hair grays/whites
Less vitamin D production Needed for calcium uptake in bones
Life Span ChangesAging skin shows many signs…
Hair growth slow Thins and # follicles decreases
Lowered blood supply to nail beds Dulls/hardens nails
Sensory receptors decline Less sensitive to pain/pressure
Inability to control body temperature # sweat glands drop & dermis blood vessel
numbers
Common Skin Disorders Athlete’s foot
Skin fungus infection (Tinea pedis)
Boil Bacterial infection, bacteria enter
skin via follicle
Chickenpox Varicella-zoster infection; blistery
lesions that scab
Common Skin Disorders Eczema
Dry, itchy, scaly skin (genetic)
Mole Benign skin tumor (nevus) usually pigmented brown
black
Psoriasis Red skin w/ silvery scale
Rashes Infectious
Roseola Measles Rubella 5th disease Shingles Impetigo Lyme disease RMSF Meningitis Candidiasis
Allergic Hives Penicillin Food allergies Poison ivy Cosmetics
Autoimmune Lupus Psoriasis
Skin CancerTypes Basal cell carcinoma
Most common Basal layer of epidermis Nodule, shiny bump, scar-like lesion
Squamous cell carcinoma 2nd most common Upper layers of skin (squamous) Begin as scaly red patches, open sores,
elevated with centralized depression Typically superficial
Skin CancerTypes Malignant melanoma
Most deadly Brown/black patches, nodules Look like or arise from moles
Skin CancerRisks
Fair skin, hair, eye color Family history Personal history Chronic sun exposure History of sunburns early in life Certain types of moles, # moles Freckles
Sun sensitivity, sun damage
Skin CancerDetection A
Asymmetry B
Border irregularity (scalloped, notched)
C Color variation
D Diameter > ¼ inch
E Evolution
Skin CancerTreatment
Excision Virtually all types of skin cancer are
100% curable if caught early Invasive
Lymph node testing Chemotherapy Immunotherapy
Suggested Homework Problems Chapter assessments
3-6, 9, 11-14, 17, 19-25, 27, 28 Integrative Assessments/Critical
Thinking 1-7