The Integumentary System by dfhdhdhdhjr


									The Integumentary System

        Chapter 5
• Integumentary system is the skin and the
  organs derived from it (hair, glands, nails)

• One of the largest organs
  – 2 square meters; 10-11 lbs.
  – Largest sense organ in the body

• The study of the skin is Dermatology
1. Regulation of body temperature
  – Cellular metabolism produces heat as a
    waste product .
  – High temperature
    • Dilate surface blood vessels
    • Sweating
  – Low temperature
    • Surface vessels constrict
    • shivering
2. Protection
      physical abrasion
      ultraviolet radiation

3. Synthesis and Storage of Nutrients

4. Sensation
4. Excretion/ Secretion

5. Immunity/ Resistance

6. Blood Reservoir
     8-10 % in a resting adult

• Epidermis           Skin
• Dermis
• Subcutaneous layer or hypodermis
• Stratum Germinativum (stratum basale)
  – Single layer of cuboidal to columnar cells
  – Stem cells that produce keratinocytes
  – Melanocytes - # the same for all races
    • Melanin produced in a melanosome
• Stratum spinosum (thorn-like, prickly)
  – 8-10 layers attached by desmosomes
• Stratum granulosum
  – 3-5 layers
  – Keratinization begins here

• Stratum lucidum (lucid = clear)
  – 3-5 layers of clear cells
  – Eleidin

• Stratum corneum
  – Dead, flat cells full of keratin
                 Skin Color
• Pigmentation
  – Carotene- an orange-yellow pigment that
    normally accumulates in epidermal cells.
    • (i.e. carrots and squashes)

  – Melanin- a brown, yellow-brown pigment
    produced by melanocytes.
             Skin Cancer
• Most common form of cancer
• Malignant Melanoma- extremely

• The outlook for long term survival depends
  on when the condition is detected and
• Dermal Circulation
  – Blood with abundant oxygen is bright red,
    gives skin a reddish tint.
  – When vessels are dilated, as during
    inflammation, the red tones become much
    more pronounced.
  – When the vessels are temporarily consricted,
    as when you are frightened, the skin becomes
• Connective tissue layer
• Collagen and elastic fibers, nerves, blood
  vessels, muscle fibers, adipose cells, hair
  follicles and glands.
• Papillary layer
  – 1/5 of dermis – loose areolar connective
  – Highly vascular
  – Dermal papillae - fingerprints
• Reticular (net) layer
  – Dense irregular connective tissue
  – Both elastic fibers and collagen fibers are

• Other Dermal Components
  – Sebaceous (oil) glands
  – Hair follicles
  – Ducts of sudoriferous (sweat) glands
  – Striae or stretch marks
         Subcutaneous Layer
• Attaches the reticular layer to the
  underlying organs
• Boundary between dermis and
  hypodermis is indistinct
• Consists of loose connective tissue and
  adipose tissue (“baby fat”)
• Major blood vessels and lack of vital
  organs makes useful method for
  administering drugs.
   Accessory organs or epidermal
• Hair and Hair Follicles
• Structure:
  – Hair papilla- peg of connective tissue
    containing capillaries and nerves.

  – Hair root- the portion that anchors the hair into
    the skin

  – Hair shaft- the part we see on the surface
• Hairs grow and are shed according to a
  hair growth cycle based on the activity
  level of hair follicles.

• Hair in the scalp grows for 2-5 years at a
  rate of about .3mm per day.
• Hair Functions:
  – Protection from UV light
  – Insulation
  – Entry of foreign particles
  – Touch and sensation
  – Arrector pilli- “goose bumps”
• Plates of highly packed, keratinized cells
• Protection, scratching, & manipulation
• Formed by cells in nail bed called the
  matrix ( in area of lunula)
• Grows about 1 mm / week
• Eponychium - cuticle
                Skin Glands
• Sebaceous (oil) glands
  – Usually connected to hair follicles
  – Holocrine glands
  – Fats, cholesterol, proteins, salts, and cell
  – Moistens hair and waterproofs skin
  – Sebum- lubricates the hair and skin and
    inhibits growth of bacteria
• Sweat (sudoriferous) glands
  – Merocrine (eccrine) sweat glands
    • merocrine glands
    • Secrete water, salt, wastes
    • Function is to cool the body (also nervous)

  – Apocrine sweat glands
    •   Larger, merocrine glands
    •   Associated with hair follicles
    •   More viscous – fatty acids and proteins
    •   Odor occurs when broken down by bacteria
• Ceruminous glands
  – Modified sudoriferous glands
  – Secrete cerumen (ear wax)

• Mammary glands
  – Secrete milk
              Wound healing
• Inflammation
  – Blood vessels dilate and become permeable
     • Heat, redness, swelling and pain

• Shallow cuts
  – Epithelial cells migrate
  – Contact inhibition
            Deeper wounds
• Inflammatory phase
  – Fibrin forms clot
• Migratory phase
  – Fibroblasts make granulation tissue
• Proliferative phase
• Maturation phase
• Scars – hypertrophic scar
• First degree or partial thickness burn
  – Only epidermis is damaged
  – Erythema, mild edema, surface layer shed
  – Healing – a few days to two weeks
  – No scarring
• Second degree- deep partial-layer burn
  – Destroys epidermis
  – Blisters form
  – Healing depends on survival of accessory
  – No scars unless infected
• Third degree or full-thickness burn
  – Destroys epidermis, dermis and accessory
    organs of the skin
  – Healing occurs from margins inward
  – Skin grafting may be needed
     • Autograft
     • Homograft

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