anaphy integ

• Integumentary System


  Consists of the skin, and accessory structures such as hair, glands, and nails
• Functions of the Integumentary System

  • Protection
  • Sensation
  • Vitamin D production
  • Temperature regulation
  • Excretion
• Epidermis


  Most superficial layer, stratified squamous epithelium, mitosis occurs in deepest layers
• Keratinization


  Transformation of the living cells of the stratum basale into the dead squamous cells of the stratum corneum
• Stratum basale


  Deepest layer, cuboidal & columnar cells, undergo mitosis every 19 days
• Stratum corneum


  Most superficial stratum, dead squamous cells filled with keratin, lipids, joined by desmosomes
• Callus


  Thickened area
• Corn


  Bony prominence, thickened corn shaped structure
• Dermis


  Dense collagenous connective tissue, contains fibroblasts, adipocytes, macrophages, nerves, hair follicles, smooth muscles, glands, lymphatic vessels
• Collagen and elastic fibers

  Provide structural strength
• Cleavage lines/Tension lines


  Collagen fibers are oriented in some directions, skin is most resistant to stretch along these lines
• Stretch marks


  Skin is overstretched, leaving lines that are visible
• Dermal papillae


  Contain blood vessels that supply the epidermis with nutrients, remove waste products, and regulate body temperature
• Melanin


  Pigments responsible for skin, hair, eye color
• Melanin pigments


  • Yellow (Caucasian)
  • Brown (Asians)
  • Black (African)
• Melanocytes


  Produce melanin, irregularly shaped cells in the stratum basale
• Melanosomes


  Vesicles derived from the Golgi apparatus where melanin is produced
• Factors of Melanin Production

  • Genetic factors
  • Exposure to UV light
  • Hormones
• Albinism

  Recessive genetic trait that causes deficiency / absence of melanin
• Cyanosis

  Bluish skin color, decreased blood oxygen
• Carotene

  Yellow pigment in plants, source of vitamin A
• Birthmarks

  Congenital disorder of the capillaries in the dermis
• Subcutaneous Tissue

  Attaches the skin to underlying bones, also called the hypodermis, loose connective tissue, storage of body fat
• Hair

  Columns of dead, keratinized epithelial cells, produced in the hair bulb
• Hair Follicle Components

  • Hair follicle - where each hair rises
  • Shaft - above the skin
  • Root - below the skin
  • Hair bulb - site of hair cell formation
  • Cortex - hard keratin
  • Medulla - soft central core
  • Cuticle - single layer of overlapping cells that holds the hair in the hair follicle
• Hair Growth

  1. Hair is formed by epithelial cells within the hair bulb

  2. Divide and undergo keratinization

  3. Hair root + shaft = columns of dead keratinized epithelial cells
• Hair Resting Stage

  1. Growth stops

  2. Hair is held in the hair follicle
• Next Hair Growth Stage

  1. A new hair is formed

  2. The old hair falls out
• Eyelashes

  Grow for about 30 days, rest for 105 days
• Scalp hairs

  Grow for 3 years, rest for 1 - 2 years
• Arrector Pili

  Smooth muscles, contraction = hair to stand on end, produces goose bumps
• Sebaceous Glands

  Simple, branched acinar glands, connected by a duct to the superficial part of the hair follicle, secrete sebum - oily, white substance rich in lipids, released by holocrine secretion, lubricates the hair/surface of the skin
• Eccrine Sweat Glands

  Simple, coiled, tubular glands, release sweat by melocrine secretion, numerous in the palms and soles
• Apocrine Sweat Glands

  Simple, coiled, tubular glands, produce a thick secretion rich in organic substances, released primarily by melocrine secretion, some glands demonstrate holocrine secretion, open into hair follicles, in armpits and genitalia, become active at puberty
• Ceruminous Glands

  Secrete cerumen (earwax)
• Mammary Glands

  Secrete milk
• Nails

  Dead stratum corneum cells, contain a very hard type of keratin
• Nail Components

  • Nail body - visible part of the nail
  • Nail root - part of the nail covered by skin
  • Cuticle - eponychium, stratum corneum that extends onto the nail body
  • Nail matrix - produces the nail
  • Nail bed - contributes to nail formation
  • Lunula - white, crescent-shaped area, part of the nail matrix visible through the nail body
• Functions of the Integumentary System

  • Reducing water loss
  • Prevents microorganisms from entering the body
  • Protects underlying structures against abrasion
  • Hair on head = insulator
  • Eyebrows = keep sweat out of the eyes
  • Eyelashes = protects the eyes from foreign objects
  • Hair in the nose, ears = prevents the entry of dust
  • Nails = protect the ends of the fingers, toes from damage; can be used in defense
• Sensation

  Sensory receptors for pain, touch, hot, cold, pressure