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The Integumentary System

Explore the body's largest organ, the skin, and its crucial roles such as protection, thermoregulation, sensation, and metabolic functions. Learn about the layers of the epidermis, dermis, and hypodermis in detail.

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The Integumentary System

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  1. The Integumentary System The skin and its accessories

  2. General Features • Body’s largest organ • Surface area of 1.2 to 2.2 square meters • 4-5 Kilograms (7% of body weight) • 1.5-4.0 millimeters thick (paper towel) • Damage impairs nearly every other system

  3. Protection-Provides a chemical, physical(mechanical) and biological barrier Thermoregulation-Body temperature regulation Sensory Organ-temperature, pressure, touch, and pain Metabolic-Synthesis Vitamin D Excretion-Small amounts of Nitrogenous wastes, water and salt Blood reservoir Functions

  4. General Structure • Epidermis • Dermis • Hypodermis /Subcutaneous (not offically considered a part of the skin, but important none the less)

  5. Stratum corneum-outer most layer; 20-30 cell layers thick; 3/4 of epidermal layer Stratum Granulosum-3-5 cell layers; last layer of the epidermis to receive nourishment Stratum Basale/Germinativum-rapidly dividing cells; melanocytes lie directly above these cells Epidermal Layers

  6. Keratin producing cells Constantly rubbing off Upper cells are dead Forms an outer protective barrier Melanin producing cells Deepest layer Protect dividing cells beneath them Epidermis Cell Types Keratinocytes Melanocytes

  7. Keratin Protein found in the epidermis, hair and nails that makes those structures hard and water-repellent.

  8. Melanin Dark pigment formed by melanocytes; imparts color to hair and skin

  9. EpidermisThick Skin Thin Skin

  10. Dust Mite & Epidermal Cell

  11. Cell types: fibroblasts, macrophages, WBC’s Fibers: collagen; reticular, elastic Other Structures: nerve fibers;blood vessels; hair follicles; glands Features of the Dermis

  12. Dermis

  13. Dermis • “True Skin” • Acts like a “body stocking” to hold the body together • Connective tissue; highly vascularized

  14. Loosely woven Dermal papilla form ridges to make finger-prints Lots of blood vessels 80% of the dermis Very dense and collagen rich Layers of the DermisPapillaryReticular

  15. Hypodermis or Subcutaneous Layer Although not officially considered a part of the skin, it must be examined in order to fully comprehend integumentary structure.

  16. Storage site for adipose tissue Loosely anchors the skin to underlying muscle. Sliding allows blows to slide off and allows movement. Features of the Hypodermis

  17. Melanin: Ranges from yellow to reddish-brown to black. Absorbs radiation from UV light to protect dividing cells beneath it. Hemoglobin: Imparts a pinkish tint; lack of O2 gives a bluish cast (Cyanosis) Carotene: Orange to yellow pigment found in many vegetables; accumulates in the stratum corneum Factors Determining Skin Color

  18. Effects of Aging • Fewer melanocytes • Fewer active hair follicles • Decreases sebaceous gland activity • Thin epidermis • Reduced sweat gland activity • Reduced blood supply • Thinner dermis

  19. FYI: One Square Inch of Skin Contains • 65 Hairs  • 95-100 sebaceous glands 650 sweat glands  • 78 sensory apparatuses (for heat) 1,300 nerve ending to record pain   • 13 sensory apparatuses (for cold) 9, 500, 000 cells  • 19 yards ( 17 mtrs) of blood vessels 78 yards (70 mtrs) of nerves  • 19,500 sensory cells at the ends of nerve fibres  • 160-165 pressure apparatuses for the perception of tactile stimuli.

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