The Skin

Skin as an organizing model:

  • What is it?
    • Skin is made up of three layers: epidermis, dermis, hypodermis (fatty later)
    • Skin is a vital organ
    • Covers the outside of the body
    • Protective barrier against pathogens and injuries
    • The largest organ at 2mm thick, 6 lbs
    • There are 2 general types of skin:
    • Thin and Hairy
    • Thick and Hairless
  • What does it do?
    • Protection
    • Air = Desiccation
    • Water = Bloating / Pruning
    • Sun/U-V = Burns
    • Cold/heat = frostbite/heatstroke
    • Structural Integrity
    • The integrity of the body
  • How does it do it?
    • Protection (mostly epidermis)
    • Desiccation - keratin, lipid layer
    • Water - keratin, lipid layer
    • Sun/U-V - role of pigment / melanin
    • Cold/heat - surface blood vessels
    • Structural (mostly dermis)
    • Integrity - dermal layer has a network of tough collagen fibers in connective tissue
    • What else does skin do?
    • Regulated body temperature
    • Gathers sensory information from the environment
    • Stores water, and fat, and synthesizes vitamin D
  • What is it made of?
    • Layers of Skin
    • Epidermis = epithelium
    • Dermis = connective tissue
    • Specialized Cells and Structures
    • Basket cells: surround the base of hair follicles and can sense pressure. Evaluated when assessing nerve health.
    • Blood Vessels: can carry nutrients and oxygen-rich blood to the cells that make up layers of skin
    • Hair Erector Muscle (Arrector Pili Muscle): Tiny muscle connected to each hair follicle and the skin. When it contracts, the hair stands erect
    • Hair Follicle: a tube-shaped sheath that surrounds the part of the hair that is under the skin and nourishes the hair
    • Hair Shaft: the part of the hair that is above the skin
    • Langerhans Cells: Attach themselves to antigens that invade damaged skin and alert the immune system to their presence
    • Melanocyte: a cell that produces melanin, and is located in the basal layer of the epidermis. touch sensitive
    • Pacinian corpuscle: a nerve receptor located in the subcutaneous fatty tissue that responds to pressure and vibration
    • Sensory Nerves: skin is innervated with these
      • sense and transmit heat, pain, and other sensations
    • Stratum Corneum
      • the outermost layer of the epidermis
    • Glands
    • Sebaceous Gland - empties oily secretion into the hair follicle
    • Sweat gland - small tubular structures within the subcutaneous
    • Ceruminous gland - specialized sudoriferous glands located in the EAC. Mixes with sebaceous to form cerumen