Skin

• What are the main components of the skin structure?

  Skin, epidermis, dermis, subcutaneous tissue, hair follicles, glands, and blood vessels
• What are the general functions of the integumentary system?

  • Protection against UV light, organisms, dehydration, and injury
  • Sensation of heat, cold, touch, pressure, and pain
  • Temperature regulation through blood flow and sweating
  • Vitamin D production via UV light
  • Excretion of small amounts of waste products
• What is the epidermis primarily composed of?

  Stratified squamous epithelial tissue
• How many sub-layers does the epidermis consist of?

  Five sub-layers (strata)
• What are the main functions of the epidermis?

  • Protection against injury and harmful UV light
  • Protection against chemicals and microorganisms
  • Prevention of water loss
  • Production of Vitamin D
  • Gives rise to hair and nails
• Does the epidermis contain blood vessels?

  No, it does not contain blood vessels
• What are the main cell types found in the epidermis?

  Keratinocytes, melanocytes, Langerhans cells, and Merkel cells
• What is the role of keratinocytes in the epidermis?

  • Provide durability to the epidermis
  • Produce keratin, a protective protein
• What do Langerhans cells do in the epidermis?

  • Function in the immune system
  • Help protect against pathogens
• What is the function of Merkel cells in the epidermis?

  • Detect light touch and superficial pressure
• What is the stratum corneum composed of?

  25 layers of dead cornified cells
• What is the significance of soft keratin in the stratum corneum?

  It provides structural strength and prevents water loss
• What happens in the stratum granulosum?

  Keratohyalin granules accumulate and cells begin to die
• What occurs in the stratum spinosum?

  Cells change shape and increase in keratin fibers
• What is the function of the stratum basale?

  It is where mitosis of keratinocyte stem cells occurs
• How is skin color determined?

  • Levels of pigment (melanin)
  • Amount of circulating blood
  • Thickness of stratum corneum
• What are the melanin-dependent factors determining skin color?

  • Type and amount of melanin produced
  • Size and number of melanosomes
  • Melanosome distribution
  • Genetic mutations (e.g., albinism)
• What are the melanin-independent factors affecting skin color?

  • Changes in blood flow
  • Erythema and cyanosis
  • Presence of other pigments (e.g., carotene)
  • Thickness of stratum corneum
• What are the key features of the dermis?

  • Thicker layer of skin consisting of connective tissue
  • Contains two layers: papillary and reticular
  • Various cell types: fibroblasts, adipocytes, macrophages
  • Extensive extracellular matrix: collagen, elastin, reticular fibers
• What are the main functions of the dermis?

  • Provides structural strength and flexibility
  • Facilitates exchange of gases, nutrients, and waste
  • Sensation: pain, itch, temperature, and touch
• What are the sensory receptors found in the dermis?

  • Free nerve endings (pain, tickle, temperature)
  • Hair follicle receptors (light touch)
  • Meissner corpuscles (touch)
  • Pacinian corpuscles (deep pressure)
  • Ruffini end organs (continuous touch)
• What are the features of the papillary layer of the dermis?

  • Loose connective tissue with thin fibers
  • Brings blood vessels near the epidermis
  • Contains dermal papillae and friction ridges
• What are the features of the reticular layer of the dermis?

  • Main dermal layer, dense irregular connective tissue
  • Contains collagen and elastic fibers
  • Generates cleavage lines or tension lines
• What is the role of the subcutaneous tissue (hypodermis)?


  • Attaches skin to underlying bones and muscles
  • Stores lipids for energy, insulation, and padding
  • Supplies blood vessels and nerves to the dermis
• What types of cells are found in the subcutaneous tissue?

  Fibroblasts, adipocytes, and macrophages
• How is total body fat estimated using subcutaneous tissue?

  Through the pinch test
• How does the amount of subcutaneous fat vary?

  It varies with age, sex, and diet
• What is the function of melanocytes in the epidermis?


  Produce melanin for skin colour