The Integumentary System

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The Integumentary System

• How does our skin protect us from the outside
  world?

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Functions
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Thick vs. Thin Skin
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Barrier Function

• Epidermis- primary function as a barrier
• Physical Barrier
• Stratum corneum sheds about 30,000 cells a minute
• Thats about 40 pounds of skin in a lifetime!

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Barrier Function

• The keratinocytes in the stratum corneum provide
  a physical barrier they are produced in the basal
  layer and migrate superficially as they mature.

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Barrier Function

• Cells in the stratum spinosum are tightly linked
  together to provide a waterproof layer
• The desmosome junctions hold the cells together

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Barrier Function

• The undamaged epidermal region prevents bacteria,
  single celled parasites and viruses from entering
  the body.

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Barrier function

• Langerhans cells in the stratum spinosum
  activate the immune system when foreign
  particles, bacteria, or viruses enter the
  epidermis

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Barrier Function

• Melanocytes in the basal layer produce melanin
• Melanin is a pigment protein that protects
  underlying layers from damaging UV rays

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Barrier Function

• Mucous,salvia, and wax secreting glands in
  epidermal linings help prevent particulates from
  entering the body through the nose, mouth and
  ears.

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Homeostatic Function

• Your body is 65-75 water.
• The upper epidermal layers prevent constant water
  loss from the body

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Homeostatic function

• The sweat glands excrete to help regulate body
  temperature by evaporative cooling.
• Sweat is 99 water

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Homeostatic Function

• Adipose (fat) tissue in the hypodermis
  (superficial fascia) helps regulate temperature
  by insulating underlying tissue

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Excretory function

• Found in the axillary and anogenital regions
• Apocrine sweat contains fats and proteins
• Bacteria digest these and create body odor

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Sensory Functions

• Touch or pressure sensors are located
• Merkel cells in the epidermis sense pressure an
  send signals to the sensory nerves in the dermis

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Light Touch

• Meissners corpuscles act as very sensitive touch
  sensors
• Located in the upper dermis

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Deep touch and Pressure

• Pacinian corpuscles receive and send deep
  pressure signals

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Pain

• Free nerve endings conduct pain

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Secretory Function

• Cells in the stratum spinosum and stratum basale
  produce Vitamin D using energy from sunlight

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Secretory Function

• Sebaceous glands in the dermis produce oil to
  lubricate hair

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Secretory Function