SKIN AND THE INTEGUMENTARY SYSTEM

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SKIN AND THE INTEGUMENTARY SYSTEM

• A. THE SKIN
• 1. The skin is an organ which consists of several
  types of tissues and performs several specialized
  activities.
• 2. The tissues comprising the skin are the
  epithelium of the EPIDERMIS and the connective
  tissues of the DERMIS.
• 3. The numerous functions of the skin include
  regulation of body temperature, protection,
  reception of stimuli, excretion, synthesis of
  vitamin D, and immunity.

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A. THE SKIN

• 4. The two principal layers of the skin are the
  EPIDERMIS and the DERMIS.
• 5. The EPIDERMIS is composed of stratified
  squamous epithelium and contains several cell
  types.
• 6. The CELL TYPES found in the epidermis are
  KERATINOCYTES, MELANOCYTES, LANGERHANS CELLS and
  GRANSTEIN CELLS.

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A. THE SKIN

• 7. The epidermis is organized into five DISTINCT
  LAYERS. These are the STRATUM CORNEUM, STRATUM
  SPINOSUM, STRATUM GRANULOSUM, STRATUM LUCIDUM and
  STRATUM BASALE.
• 8. The skin is capable of regeneration.
• 9. The DERMIS consists of two distinct regions.
  The upper, PAPILLARY REGION, is composed of loose
  connective tissue and elastic fibers and the
  lower, RETICULAR LAYER, is composed of dense,
  irregularly arranged connective tissue and
  collagenous and elastic fibers.

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A. THE SKIN

• 10. Lines of cleavage on the surface of the skin
  overlie dermal regions where collagen fibers are
  oriented in a specific fashion. These are
  referred to as the DERMATOMES.
• 11. SKIN COLOR is due to MELANIN in the
  epidermis, CAROTENE in the dermis and blood in
  the capillaries of the dermis. Differences in
  skin color are due to the amount of melanin
  produced and the extent of its dispersal.
• 12. MALIGANANT MELANOMA (cancer of the
  melanocytes), is a particularly serious skin
  cancer. Liver, or age spots, are noncancerous
  clusters of melanin.

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B. ACCESSORY ORGANS OF THE SKIN

• 1. The accessory organs of the skin include HAIR,
  GLANDS AND NAILS.
• 2. HAIR is distributed variously over the body
  where it functions in protection. Each hair is
  composed of a SHAFT and a ROOT.
• Surrounding the root is the HAIR FOLLICLE, which
  is composed of two layers of epidermal tissue.

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B. ACCESSORY ORGANS OF THE SKIN

• 3. Skin glands include SEBACEOUS (OIL),
  SUDORIFEROUS (SWEAT), and CERUMINOUS (WAX)
  glands.
• 4. SEBACEOUS GLANDS, with few exceptions, are
  associated with the hair follicle and secrete an
  oily substance called SEBUM which prevents skin
  dryness and water evaporation.

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B. ACCESSORY ORGANS OF THE SKIN

• 5. Blackhead or pimples represent enlargement of
  the sebaceous glands due to unreleased quantities
  of sebum.
• 6. SUDORIFEROUS GLANDS, OR SWEAT GLANDS, can be
  divided into APOCRINE glands and ECCRINE glands.
• 7. APOCRINE glands are found in the armpit, pubic
  region and the pigmented area of the breasts.

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B. ACCESSORY ORGANS OF THE SKIN

• 8. ECCRINE glands are found throughout the skin
  except the lips, nail beds, glans penis, glans
  clitoris, labia minora and eardrums.
• 9. CERUMINOUS glands are modified sudoriferous
  glands present in the external ear. They produce
  a sticky substance called CERUMEN which provides
  a barrier against foreign bodies.
• 10. NAILS are hard keratinized epidermal cells
  over the dorsal surfaces of the terminal portions
  of the fingers and toes.

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C. HOMEOSTASIS AND BODY TEMPERATURE

• 1. The skin helps to regulate the homeostasis of
  body temperature through a negative feedback
  system.
• 2. Perspiration from sweat glands and dilation of
  the superficial blood vessels help to remove
  excess heat from the body.
• 3. Constriction of the blood vessels in the skin
  aids in conserving heat when body temperature
  drops.

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C. HOMEOSTASIS AND BODY TEMPERATURE

• 4. BURNS can destroy the proteins in the exposed
  cells and cause injury or death.
• Burns are classified by depth.
• 5. FIRST-DEGREE and SECOND-DEGREE burns are
  called partial-thickness burns.
• 6. THIRD-DEGREE burns are termed full-thickness
  burns.
• 7. The LUND-BROWDER method is one which is used
  to approximate the extent of burns. The rule of
  nines can be used for a more rapid, if somewhat
  less accurate assessment of the extent of burns.