The Integumentary System
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Transcript of The Integumentary System
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The Integumentary SystemChapter 5
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Cool Skin Facts:Surface Area = 1.2-2.2 sq.m(1/2 white board)
Weight = 4-5 kg (8-9lbs)7% of body weight
Thickness – 1.5-4.0 mmMillions rub off each day- New epidermis every 25-45 days
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Two Regions
Epidermis
Dermis
Composed of epithelial tissue Outermost layer Non-vascular Keratinized stratified squamous
epithelium
Composed of fibrous connective tissue Underlying layer vascularized
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Cells of the epidermis Keratinocytes- produce keratin, tightly
connected by desmosomes, continuous mitosis Melanocytes-pigment called melanin(protects
from UV), spider-shaped cells, found in deepest layer of epidermis
Merkel cells-shaped like spikey hemisphere, Merkel disc has sensory function
Langerhans cells -made on bone marrow, macrophages
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Layers of Epidermis Stratum Basale- ( Basal Layer) bottom,
attached to dermis, youngest keratinocytes, 10-25% are melanocytes
Stratum Spinosum (Prickly Layer) intermediate filaments resist tension attach to desmosomes, keratinocytes appear spiny
Stratum Granulosum (Grandular layer) 3-5 layers thick, keratinocytes flatten, accumulate keratohyaline and lamellated granules
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Epidermis layers cont. Stratum Lucidum (clear layer)- thin,
translucent, dead keratinocytes Stratum Corneum (Horny Layer)- 20-30
layers thick, ¾ of epidermal thickness, 40 lbs shed in lifetime
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DermisPapillary and Reticular Layers
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Papillary Thin, blood vessel rich, areolar
connective, collagen and elastin fibers, loosely woven
Dermal papillae- indent overlying epidermis, touch receptors(Meissner’s corpuscles), fingerprints
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Reticular Layer 80% of thickness of dermal layer Dense irregular connective tissue Extra cellular matrix contains thick
bundles of interlacing collagen fibers, form cleavage, tension and lines in the skin, flexure lines (at joints)
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Skin Pigments Melanin-
› Protects from UV› All have same
number only make different amounts
Carotene-› Yellow to orange› Accumulates in fatty
tissue and stratum corneum (soles of feet and palms)
› *Hemoglobin (found in Red blood cells) can give reddish hue
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Skin color signs of diseases Redness (erythema)- embarrassment,
fever, hypertension, inflammation, allergy
Pallor (pale)- fear, anger, stress, anemia, low blood pressure
Jaundice (yellow)- liver disorder, bile pigments accumulate in body tissues, bilirubin secreted by liver cells as component of bile
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Skin diseases continued…. Bronzing-Addison’s disease,
hypofunction of adrenal cortex Black and blue marks- hematomas
(bruise)
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Appendages of the skin Nails Sweat glands (sudiferous glands) pH 4-6
› Eccrine (merocrine)-palms, soles of feet, forehead
› Apocrine gland- hair follicles, body odor, musky, unknown function
› Other- ceruminous glands (ear wax)› Mammary glands- milk
Sebaceous glands (oil) Hair
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Sebaceous Oil glands Found everywhere except palms, soles
of feet Holocrine gland Sebum- oily Soften and lubricates hair Bactericidal action Seborrhea – “cradle cap”
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Nails Hard Keratin
http://www.thaimedicalnews.com/wp-content/uploads/healthy-finger-nails-diagram.gif
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Hairs and Hair Follicles Sense insects before they sting Head hair protects against UV, heat
loss, physical trauma Eye lashes- shield eyes Nose hairs- filter large particles like lint
and insects
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Structure of Hair Pili-”hairs” consist of largely dead,
keratinized cells. Hard keratin-tough and durable,
individual cells do not flake off Soft Keratin- found in typical epidermal
cells
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3 Concentric Layers of the Hair
Medulla- core, large cells and air spaces, not found in fine hairs
Cortex- bulky layer surrounding medulla,
several layers of flattened cells Cuticle-single layer of cells, overlaps on
another like shingles *Red heads have trichosiderin- iron-
containing pigment
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Hair Follicle Structure
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Types of Hair Vellus Pale, fine Females and
children
Terminal Coarser Scalp and eyebrows Androgen
stimulates
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Hair Growth Facts Hirsutism- excessive
hairiness, caused by excessive androgens
2.5 mm/week Lose about 90
hairs/day
Growth cycle› Active (anagen)› Regressive
( catagen)› Resting phase
(telogen)
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Hair thinning and Baldness Alopecia- hair
thinning or baldness Drug induced Excessive vitamin A Chemotherapy Burns Radiation Alopecia areata-
autoimmune
Male Pattern Baldness
Minoxidil treatment
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Functions of the Integumentary System
Protection› Chemical, physical, and biological barriers
Body Temperature Regulation Cutaneous Sensation Metabolic Functions Blood Reservoir Excretion
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Additional Facts . . . Low pH retards bacterial growth (acid
mantle) Natural antibiotic (human defensin) Cathelicidins – fights strep bacteria Some substances can penetrate skin,
ie. Lipid-soluble substances (oxygen, Carbon dioxide, vitamins A,E,D,K), oleoresins (poison ivy)
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More . . . Organic solvents (ie. Acetone, paint
thinner, etc.) Salts of heavy metals (lead, mercury,
nickel) May lose 12 L of body fluid per day Can transform cortisone into
hydrocortisone 5% of blood volume in skin Lose water and salt through skin
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Homeostatic Imbalances Skin Cancer- benign and malignant,
p53 gene (tumor suppressor gene) Types of Skin cancer:
› 1)Basal Cell carcinoma› 2)Squamous cell carcinoma-arises from
keratinocytes in stratum spinosum› 3)Melanoma- cancer of melanocytes
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Skin cancer checklist
A rule : asymmetry B rule : border irregularity C rule: color D rule: diameter E rule : elevation
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Burns First degree: epidermis only damaged,
redness, swelling, pain, heals in 2-3 days
Second degree: epidermis and upper region of dermis, blisters, 3-4 weeks no scarring
Third degree: all layers, appears gray-white, cherry red, or blackened, not painful because nerve endings, skin grafing
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Other interesting facts: Lanugo coat- 5-6 month fetus, delicate
coat of hairs Vernix caseosa- cheesy substance on
newborns