Integumentary System

• What is the integumentary system also known as?

  Integument
• What percentage of body weight does the integumentary system account for?

  16%
• What is the surface area of the integumentary system?

  1.5-2 square meters
• What are the main components of the integumentary system?

  • Cutaneous membrane (skin)
  • Epidermis (superficial epithelium)
  • Dermis (deep connective tissue)
  • Accessory structures
  • Hair
  • Hair follicles
  • Nails
  • Exocrine glands
• What does the integumentary system contain that is important for sensation?

  Blood vessels and sensory receptors
• What is the subcutaneous layer also known as?

  Hypodermis
• What is the function of the subcutaneous layer?

  It stabilizes the position of the skin and connects the dermis to underlying tissues
• What are the functions of the integumentary system?

  • Protection against impact, abrasion, fluid loss, and chemical attack
  • Excretion of salts, water, and organic wastes
  • Maintenance of normal body temperature
  • Production of melanin and keratin
  • Synthesis of vitamin D
  • Storage of lipids
  • Detection of various stimuli
  • Coordination of immune response
• What is the primary function of keratin in the skin?

  To make skin tough and repel water
• How does the integumentary system help in temperature regulation?

  Through insulation and evaporative cooling
• What type of epithelium is the epidermis composed of?

  Stratified squamous epithelium
• Why is the epidermis considered avascular?

  Because it does not contain blood vessels
• What are the main cells found in the epidermis?

  Keratinocytes
• What do keratinocytes contain that is significant for skin function?

  Large amounts of keratin
• What are the two types of skin and their characteristics?

  • Thin skin
  • Covers most of the body
  • Has four layers in the epidermis
  • Thick skin
  • Covers palms and soles
  • Has five layers in the epidermis
• What are the five strata of the epidermis from deep to superficial?

  1. Stratum basale
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum lucidum
  5. Stratum corneum
• What is the role of the stratum basale in the epidermis?

  It contains stem cells that divide to produce new keratinocytes
• What are epidermal ridges and their significance?

  Projections that interlock with dermal papillae to increase surface area for attachment
• What specialized cells are found in the stratum basale?

  Tactile (Merkel) cells and melanocytes
• What is the function of tactile (Merkel) cells?

  They serve as sensory receptors for touch
• What is the role of dendritic (Langerhans) cells in the stratum spinosum?

  They defend against microorganisms and skin cancers
• What happens to cells as they move from the stratum spinosum to the stratum granulosum?

  They stop dividing and fill with keratin and keratohyalin
• What is keratinization?

  The formation of protective layers of cells filled with keratin
• How long does it take for new cells to move from the stratum basale to the stratum corneum?

  7-10 days
• What is insensible perspiration?

  Loss of water that diffuses across the stratum corneum and evaporates
• How much water is lost through insensible perspiration daily?

  Approximately 500 mL
• What is the role of epidermal growth factor (EGF)?

  It promotes division of basal cells and accelerates keratin production
• What are the layers of the dermis and their characteristics?

  • Dermis: deeper layer of skin
  • Anchors epidermal accessory structures
  • Contains blood vessels and nerves
  • Layers:
  • Superficial papillary layer
  • Deeper reticular layer
• What is the papillary layer of the dermis composed of?

  Areal tissue
• What is dermatitis?


  Inflammation of the dermis
• What is the reticular layer of the dermis composed of?

  Dense irregular connective tissue rich in collagen and elastic fibers
• What is the function of collagen fibers in the dermis?

  They add strength and limit flexibility to prevent tissue damage
• What happens to skin turgor when there is dehydration?

  The tensile strength and elasticity of the skin decreases
• What are tension lines in the skin?

  Patterns produced by parallel bundles of collagen and elastic fibers
• How do cuts made parallel to tension lines heal compared to those made perpendicular?

  Parallel cuts heal well with minimal scarring, while perpendicular cuts scar more
• What is the cutaneous plexus?

  A deep network of vessels along the border of the reticular layer of the dermis
• What is a contusion?

  A bruise caused by damage to blood vessels in the dermis
• What do tactile (Meissner) corpuscles detect?

  Light touch
• What do lamellar (Pacinian) corpuscles detect?

  Deep pressure and vibration
• What is the function of the subcutaneous layer?

  • Stabilizes the position of the skin
  • Connects the dermis to underlying tissues