Integumentary System

• What is the largest and heaviest organ of the body?

  Skin
• What percentage of total body weight does the skin represent?

  16%
• What is the surface area of the skin?

  1. 5-2.2 m²
• What are some of the environmental factors the skin is exposed to?

  Microorganisms, sunlight, environmental chemicals
• What are the properties of the skin mentioned in the material?

  Waterproof, stretchable, washable, permanent-press
• What is the primary function of the integument?

  Protection
• What are the general functions of the integument?

  • Protection against abrasion & UV light
  • Entry of microorganisms
  • Prevent dehydration
  • Excretion of salts, water, and organic wastes
  • Temperature regulation
  • Synthesis of vitamin D
  • Cutaneous sensation (touch, pressure, pain, temperature)
  • Nonverbal communication
• What are the two major components of the integumentary system?

  Cutaneous membrane and accessory structures
• What are the three layers of the skin?

  Epidermis, dermis, hypodermis
• What type of epithelium is the epidermis composed of?

  Stratified squamous epithelium
• How is the epidermis nourished?

  By diffusion from dermal capillaries
• What is keratinization?

  Process where cells fill with keratin and die
• What are melanocytes responsible for?

  Producing pigment for skin color
• What is desquamation?

  Shedding of older skin cells
• What are the four main types of cells in the epidermis?

  Melanocytes, dendritic cells, tactile cells, keratinocytes
• What are the layers of the epidermis from innermost to outermost?

  1. Stratum Germinativum
  2. Stratum Spinosum
  3. Stratum Granulosum
  4. Stratum Lucidum
  5. Stratum Corneum
• What characterizes thick skin?

  All 5 epithelial strata present
• Where is thick skin found?

  Palms of hands, fingertips, soles of feet
• What characterizes thin skin?

  Only 4 layers of epidermis
• What is the stratum germinativum known for?

  It contains stem cells that divide
• What happens in the stratum spinosum?

  Stem cells divide and daughter cells move up
• What is the role of Langerhans cells?

  Stimulating immune response against pathogens
• What occurs in the stratum granulosum?

  Cells begin manufacturing keratin and keratohyalin
• What is the stratum lucidum?

  A clear layer found in thick skin
• What is the stratum corneum composed of?

  15-30 layers of dead keratinized cells

  
• What is keratinization also known as?

  Cornification
• What happens to skin cells during desquamation?

  Older cells slough off
• What is hyperkeratosis?

  Excessive production of keratin
• What are calluses?

  Thickened patches from chronic abrasion
• What is psoriasis characterized by?

  Rapid division of stem cells in the stratum germinativum
• What causes skin color variations?

  Interaction of pigment composition and blood supply
• What pigments are involved in skin pigmentation?

  Carotene and melanin
• What is the role of melanin in the skin?

  Protects against UV radiation
• What is albinism?

  Inability to produce melanin
• What are freckles?

  Localized patches of melanocytes
• What is vitiligo?

  Autoimmune loss of melanocytes
• What happens to melanocyte concentrations in sunlight?

  Increases on cheeks and forehead
• What is the effect of blood vessel dilation on skin color?

  Skin appears red with more oxygen
• What is cyanosis?

  Bluish coloration due to low oxygen
• What is the primary function of the dermis?

  Provides structural strength