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• Skin


  The largest organ of the body
• Integumentary system


  The system that includes skin and associated structures
• Functions of skin


  • Maintains internal body temperature
  • Maintains fluid balance
  • Protects internal structures and organs
  • Protects from pathogens
  • Produces Vitamin D
  • Has sensory functions
• Layers of the epidermis

  • Stratum corneum
  • Stratum lucidum
  • Stratum granulosum
  • Stratum spinosum
  • Stratum basale
• Keratinocytes


  Cells that make keratin, a protein that helps cells be water resistant and tough
• Cornified cells


  Hardened, flattened, and tough dead cells full of keratin
• Melanocytes


  Cells that make melanin, a pigment that protects skin from UV damage
• Merkel cells


  Cells thought to have involvement with the nervous system and the sense of touch
• Dermis


  Contains blood vessels, sweat glands, hair follicles, and nerves
• Dermis


  • Contains collagen fibers for support and elastin fibers for elasticity
  • Has a papillary layer and a reticular layer
• Scars


  Formed when a cut reaches the dermis, look different from original skin due to irregular collagen arrangement
• Hypodermis


  Connects the skin to bone and muscle, contains adipose tissue for insulation
• Accessory structures of the integumentary system

  • Sweat glands
  • Sebaceous glands
  • Hair
  • Nails
• Skin cancer is the most common cancer in the United States
• Basal cell carcinoma


  Most common type of skin cancer, arises from basal cells
• Melanoma


  Type of skin cancer that arises from melanocytes
• Merkel cell carcinoma


  Rare aggressive type of skin cancer that arises from Merkel cells
• Degrees of burns


  • First degree (epidermis)
  • Second degree (epidermis and part of dermis)
  • Third degree (epidermis and all of dermis)
  • Fourth degree (beyond skin layers to bones and muscles)
• Third and fourth degree burns can be less painful despite being more severe due to nerve damage
• Significant burns compromise the skin's functions of maintaining fluids and protecting internal structures, and increase risk of infection