The Integumentary System

• The integumentary system consists of?

  • skin
  • hair
  • glands
  • nails
• What are the functions of the integumentary system?

  • Protection
  • Sensation
  • Vitamin D production
  • Temperature regulation
  • Excretion
• It prevents microorganisms & other foreign substances from entering the body.

  First line of defense
• What is the 2nd line of defense?

  The concept of inflammation which involves the white blood cells
• It protects the body from microbial invasion.


  Immunoglobulin Antibodies (IgA)
• It protects underlying structures from abrasion and reduces water loss

  Stratified squamous keratinized epithelium
• The presence of keratin (protein) lessens water evaporation in the body and gives skin its water-resistant properties.

  Stratified squamous keratinized epithelium
• It absorbs UV light & protects underlying structures from UV light’s damaging effect.

  Melanin
• What is the reason we get darker skin when we are exposed to the sun?

  Skin produces more melanin when under the sun, thus the darkening of the skin.
• Receptors help the skin detect heat, cold, touch, pressure, and pain.
• What is the receptor for deep sensation?

  Pacinian corpuscle
• What is the receptor for pain?

  Free nerve endings
• The receptors under the skin cause sensation.
• Activation of vitamin D

  • (1) skin → sunlight helps turn a molecule in our skin into vitamin D3.
  • (2) liver → vit D3 goes into the liver and changes it into Calcifediol
  • (3) kidney → the kidney converts Calcifediol to Calcitriol
• Blood vessel dilates (wider/more open)


  Vasodilation
• Blood vessel constricts (narrower)

  Vasoconstriction
• Enhanced blood flow = increased heat loss


  Vasodilation
• Minimized blood flow = decreased heat loss

  Vasoconstriction
• In which organ in the human body is vitamin D created?

  Kidney
• Sweat contains small amounts of waste products, such asurea, uric acid, and ammonia.


  Excretion
• Which organ in the human body releases waste through our sweat?

  Kidney
• The largest organ in the body.

  The Skin
• The skin is made up of two major layers called?

  • epidermis
  • dermis
• Epi means?

  Above
• The epidermis is composed of?

  Stratified squamous keratinized epithelium
• This layer undergoes keratinization.

  Epidermis
• Produces keratin (toughens/hardens skin) which prevents water loss.


  Keratinization
• All but the deepest layers are composed of dead cells.

  Epidermis
• This layer has no blood vessels; composed of dead cells.

  Epidermis
• This layer contains 4-5 layers.

  Epidermis
• What keeps living cells alive in the last layer of the epidermis?

  The oxygen from the blood vessel in the papillary layer diffuses to the deep layer of the epidermis.
• What are the cells of the epidermis and dermis?

  • Keratinocytes
  • Melanocytes
  • Langerhans cells
  • Merkel cells
• 90% of epidermal cells


  Keratinocytes
• The most abundant cell in the skin, which is also found in all layers of the skin.

  Keratinocytes
• 8% of epidermal cells


  Melanocytes
• The pigment-producing cells, which are also found in stratum germinativum.

  Melanocytes
• Protective macrophagic cells  (defends body against infection) that ingest bacteria & other foreign debris.

  Langerhans cells
• The only receptor in the epidermis.

  Merkel cells
• Aid in tactile (touch) reception

  Merkel cells
• What is the difference between thick and thin skin?

  • Thick skin: 5 layers
  • Thin skin: 4 layers