Anatomy

• Functions of skin:

  • Protects from infection
  • Regulates body temperature
  • Contains nerve receptors that detect pain, sensation and pressure
  • Vitamin D production
  • Sun protection
• Skin is divided into 3 layers:

  • Epidermis
  • Dermis
  • Hypodermis
• Epidermis:

  • outmost layer of skin
  • Made up of:
  • Basal layer - base of the epidermis
  • Squamous cell layer - above the basal layer
• Basal layer of epidermis:

  • Continuously making keratinocytes that migrate upwards - flat cells full of keratin - protection and waterproofing of skin
  • Also contains melanocytes:
  • Secrete melanin
  • Type and quantity of melanin produced determines skin colour
  • Exposure to sunlight stimulates melanocytes to make more melanin which scatters UV light
  • Clustered melanocytes = mole
• Squamous cell layer of epidermis:

  • Thickest layer
  • As cells migrate up they undergo a process called keratinization
  • The keratinocytes get bigger and flatter - stick together to become squamous cells
  • As the cells migrate up they flatten out and die
  • Older dead ells on the outer layer shed off as skin flakes
• Skin cancers:

  •Basal cell carcinomas: Develop from cancerous changes in the basal layer

  •Squamous cell carcinomas: Develop from cancerous changes in the squamous cell layer

  •Melanomas: Develop from cancerous changes in melanocytes
• Dermis:

  • Divided into 2 layers:
  • Thin upper layer that contains: fibroblasts that make collagen, blood vessels, nerve endings for fine touch and pain
  • Thick deeper layer that contains: fibroblasts that make tight collagen for support and elastin for flexibility, oil, sweat glands, fair follicles, blood vessels, nerve endings for pressure and vibration
  • Dermis is important for temperature regulation and sensation
• Hypodermis (aka subcutaneous tissue):

  • Important for insulation, padding and anchoring skin to muscle, contains:
  • Adipocytes - fat cells
  • Fibroblasts - formation of connective tissue
  • Blood vessels
  • Nerves
  • Lymphatics