Skin

2 m2 and 4 kg
Structure
- Epidermis
  - Stratum corneum
  - Stratum lucidum
  - Stratum granulosum
  - Stratum spinosum
  - Stratum basale
- Dermo-epidermal junction
  - Basement membrane
- Dermis
  - Papillary dermis
    - Loosely arranged collagen
    - Supplies epidermis with nutrients through dermal papillae
  - Reticular dermis
    - Densely packed reticular, elastic, collagen fibres
  - Connective tissue
  - Dense innervation
- Subcutis/hypodermis
  - Fat
  - Connective tissue that anchors the skin to the deep fascia
Function
- Mechanical, chemical, physical, microbial barrier
  - Desmosomes attach keratinocytes to each other
  - Hemidesmosomes attach keratinocytes to basement membrane
- Protect against UV radiation
  - Melanocytes
- Immune function
  - Skin associated lymphatic tissues (SALT)
  - Langerhans cells – tissue macrophages in stratum spinosum
  - Recruits the immune system when something crosses the barrier
- Vitamin D synthesis
- Sensory
  - Touch
    - Meissner corpuscles – fine touch
    - Ruffini corpuscles – pressure
  - Vibration
    - Pacinian corpuscles
  - Temperature and pain
    - Free nerve endings
- Temperature regulation