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The Integumentary System

Delve into the integumentary system with details on skin layers, cells, pigments, structures like nails, hair follicles, glands, and disorders. Uncover the secrets of skin color, hair growth, and more.

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The Integumentary System

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  1. The Integumentary System Chapter 5

  2. 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 mm Millions rub off each day- New epidermis every 25-45 days

  3. Two Regions Epidermis • Composed of epithelial tissue • Outermost layer • Non-vascular • Keratinized stratified squamous epithelium • Composed of fibrous connective tissue • Underlying layer • vascularized Dermis

  4. 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

  5. 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

  6. 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

  7. Dermis Papillary and Reticular Layers

  8. Papillary • Thin, blood vessel rich, areolar connective, collagen and elastin fibers, loosely woven • Dermal papillae- indent overlying epidermis, touch receptors(Meissner’s corpuscles), fingerprints

  9. 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)

  10. 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

  11. 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

  12. Skin diseases continued…. • Bronzing-Addison’s disease, hypofunction of adrenal cortex • Black and blue marks- hematomas (bruise)

  13. 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

  14. Sebaceous Oil glands • Found everywhere except palms, soles of feet • Holocrine gland • Sebum- oily • Soften and lubricates hair • Bactericidal action • Seborrhea – “cradle cap”

  15. Nails • Hard Keratin • http://www.thaimedicalnews.com/wp-content/uploads/healthy-finger-nails-diagram.gif

  16. 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

  17. 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

  18. 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

  19. Hair Follicle Structure

  20. Types of Hair • Vellus • Pale, fine • Females and children • Terminal • Coarser • Scalp and eyebrows • Androgen stimulates

  21. 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)

  22. 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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