Integumentary

• What does Integumentary System Consist of?

  Organ consisting of skin and accessory structures
• Functions of the Integumentary System

  • Protection
  • Sensation
  • Excretion / Regulate Water Loss
  • Regulate Temperature
  • Vitamin D production
• Protection


  • Reduce water loss and protects against mechanical damage
  • Prevents entry of objects, microorganisms or foreign substances, aided by hair
  • Melanin absorbs UV
  • Nails protect ends of fingers and toes
• Sensation


  • Detection of pain, heat, cold or pressure
  • Hairs can detect movement
• Excretion


  • Removal of water and salts
  • Small amount of waste such as urea
• Temperature regulation


  • Alongside other reflexes, blood flow through the skin helps warm or cool
  • Hair on the head acts as an insulator
• Vitamin D Production


  • UV light aids the production of vitamin D
• Skin


  • Largest organ in the body
  • Approx 16% of body weight (3-5kg)
  • Covers approx 1.5-2 m2
  • 2-3mm Thick
  • Vital homeostatic functions
  • Must be very flexible while very tough
• Layers of the Skin

  • Epidermis
  • Dermis
  • Subcutaneous tissue (Hypodermis)

  
• Epidermis


  • Superficial layer of epithelial tissue
  • Arranged into layers called strata
  • Basement membrane interfaces with dermal papilla to anchor epidermis
  • Avascular; nourished by diffusion from capillaries of the dermal papilla

  
• Keratinocytes


  • The largest component cell of the skin
  • Produce protein keratin for strength
• Melanocytes


  • Contribute to skin color
  • Provide UV protection
• Langerhans' cells

  Part of the immune system
• Merkel's cells

  Associated with nerve endings and detect light, touch, and superficial pressure
• Desquamate


  Cells pushed towards the surface and slough (Shed) off
• Keratinization


  Regeneration – Mitosis of cells at the bottom layer followed by their maturation through the different strata to form a protective surface that resists abrasion and forms permeability layer
• Epidermal StrataConsists of?


  • Stratum Basale
  • Stratum Spinosum
  • Stratum Granulosum
  • Stratum Lucidum
  • Stratum Corneum
• Epidermal Layers and Keratinization

  1. Stratum basale – cells duplicate by mitosis

  2. Stratum spinosum – these new cells form a new layer and start to produce keratin proteins

  3. Stratum granulosum – Keratin forms a hard protein envelope, cells start to die

  4. Stratum lucidum - cells die

  5. Stratum corneum – Interlinked dead cells consisting of keratin and surrounded by lipids
• Thick skin


  • 5 Layers
  • Found in areas subject to pressure or friction
  • Palms of hands, fingertips, soles of feet
• Thin skin


  • 4 Layers
  • Less cells in each strata
  • More flexible than thick skin
  • Covers rest of body
  • Contains hair

  
• Factors determining skin color

  • Pigments
  • Blood circulating through the skin
  • Thickness of stratum corneum
• Melanin


  • Produced by Melanocytes
  • Provides protection against UV light
  • Colored brown to black ingested by keratinocytes
  • Only located in the stratum basale
• Carotene


  Yellow pigment, found in vegetables (high in carrots)
• Albinism


  Deficiency or absence of pigment