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A PChapter 5

• The Integumentary System

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Integumentary System

• Skin
• outer layer - epidermis
• inner layer - dermis
• Accessory structures
• hair nail follicles
• sensory receptors
• glands
• Subcutaneous tissue

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Skin Functions

• Protection from pathogens
• Temperature regulation
• Excretion of small amounts of urea NaCl or salt
• Formation of vitamin D from cholesterol on
  exposure to UV rays of sunlight

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Epidermis

• Outer layer
• Made up of stratified squamous epithelium
• Most abundant cells are the keratinocytes
• keratinocytes produce keratin which is a
  protein that provides structural strength to
  hair, skin nails
• Has no capillaries
• Consists of 2 layers
• stratum germinativum
• stratum corneum

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• Stratum Germinativum
• the base of the epidermis
• mitosis takes place
• production of the protein, keratin
• Merkel cells present touch receptors

• Stratum Corneum
• outermost layer of the epidermis
• many layers of dead cells
• barrier to pathogens
• keratin prevents loss entry of water

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• Langerhans cells
• phagocytize foreign material
• stimulate an immune response by the lymphocytes
  in the lymph nodes

• Melanocytes
• produce the protein melanin when exposed to UV
  rays
• melanin prevents further exposure of skin cells
  to UV rays by darkening the skin
• More melanin produced by dark skinned people

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DERMIS

• Also known as the true skin
• Inner layer of the skin
• Made of irregular fibrous connective tissue
• Contains collagen which provides strength
• Contains elastin which provides elasticity
• Has capillaries present
• Contains hair nail follicles, sensory
  receptors, glands arterioles

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Dermis

• HAIR FOLLICLES
• Only part alive is the root
• Scalp hair provides insulation from cold
• Eyelashes eyebrows keep dust perspiration out
  of the eyes
• Nostril hairs keep dust out of nasal cavities
• Pilomotor or arrector pili muscle goose bumps

• NAIL FOLLICLES
• Mitosis takes place in the nail root, the nail
  itself is dead
• Provides protection for the ends of fingers, toes
• Purpose of scratching
• may kill or dislodge an anthropod parasite,
  mosquito, tick, flea or louse which may carry a
  disease caused by bacteria, viruses, or protozoa

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Dermis continued

• Receptors detect changes in the skin touch,
  pressure, heat, cold, provide information about
  the external environment
• Sebaceous glands secrete sebum into hair
  follicles or to the skin surface which inhibits
  the growth of bacteria moistens the skin hair

• Ceruminous glands in the ear canals, secrete
  cerumen or ear wax to prevent drying of the
  eardrum
• Apocrine sweat glands located in the axilla
  genital area. Active with stress emotions.
  Secretion has slight odor, but when mixed with
  bacteria on skin a stronger odor is produced
  body odor

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Dermis continued

• Eccrine sweat glands found mainly on the
  forehead, upper lip, palms soles. Activated
  with high external temperature exercise.
• Arterioles small arteries that constrict in
  cold conditions to keep blood in center of body
  for warmth dilate in warm conditions to allow
  the release of heat from the body to keep cool.

• Vasoconstriction also occurs during stressful
  situations flight or flight mechanism shunts
  blood to the center of the body to major organs
• With prolonged interrupted blood flow to the
  dermis pressure sores or decubitus ulcers may
  form

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Decubitus Ulcer
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Subcutaneous Tissue

• Also called the superficial fascia, it connects
  the skin to muscle
• Made up of
• Areolar tissue- contains WBCs that destroy
  pathogens that may get into the body through
  breaks in the skin

• Adipose tissue storage of potential energy,
  cushions bony prominences provides insulation
  from the cold
• This layer is where injections of insulin are
  given or SQ injections Absorption is at a
  moderate rate compared to the dermal route which
  is slower