Integumentary System Lecture Powerpoint

							Integumentary System
Biology II



“The finest clothing made is a person's own skin, but, of course,
society demands something more than this.”

Mark Twain
Case Study
• The brown recluse spider has a venom that
  contains an enzyme called phospholipase.
  ▫ This destroys the phospholipid bilayer that makes
    cell membranes.
• The venom liquefies the cells of its prey, allowing
  it to feed by sucking in the nutrients.
Case Study
• Brown recluse spiders
  have small chelicerae (fangs),
  so the bite doesn’t go deep and
  the damage is superficial.



• Enzymes can be re-used over and over again, so
  the tissue damage gradually gets deeper,
  eventually reaching the blood vessels and muscle
  underneath.
Case Study
• The outermost layers of skin exist to
  prevent foreign substances from entering
  the body.
• The resulting tissue damage
  from the bite is highly
  prone to infection, as
  these outer layers are
  broken down.
 ▫ Infection is the biggest
   long-term risk from this
   injury.
• The longer the bite is left untreated, the more tissue
  damage that occurs, and the greater the risk of infection.
The Integumentary System
• The integument is the largest system of
  the body.
  ▫ 16% of body weight
  ▫ 1.5 to 2 m2 in area
• The integument is made up of two parts
     Cutaneous membrane (skin)
     Accessory structures (sweat glands,
      etc)
     Subcutaneous fat and connective
      tissue.
 • The cutaneous membrane has two
   components
     ▫ Outer epidermis
         Made of epithelial tissues.

     ▫ Inner dermis
         Made of connective tissues.




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• Accessory Structures
 ▫ Originate in the dermis
 ▫ Extend through the epidermis and
   eventually reach the skin surface
    Hair
    Nails
    Exocrine glands (sweat and oil)
The Integumentary System
 • Subcutaneous layer (a.k.a. hypodermis)
     ▫ Made of loose areolar connective tissue
     ▫ Located directly below the dermis




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The Integumentary System
 • Connections to Other Body Systems
     ▫ Cardiovascular system
         Blood vessels are present in the dermis layer.

     ▫ Nervous system
         Sensory receptors for pain, touch, and temperature
          are also present in the dermis layer.




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Injection Points
 • There are three main injection points based on
   integumentary anatomy:
     ▫ Intradermal occurs inside the dermis layer.
     ▫ Subcutaneous occurs below the dermis layer in
       subcutaneous connective tissue.
     ▫ Intramuscular goes through the entire
       integument into the muscles underneath.




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Injection Points




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Introduction to the Integumentary System
 • Functions of Skin
     ▫ Protects underlying tissues and organs
     ▫ Excretes salts, water, and organic wastes (glands)
     ▫ Maintains body temperature (insulation and
       evaporation)
     ▫ Synthesizes vitamin D3
     ▫ Stores lipids
     ▫ Detects touch, pressure, pain, and temperature


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 Epidermis
• The epidermis is made of avascular
  stratified squamous epithelium.
  ▫ Avascular means no blood vessels.
  ▫ Stratified squamous means
    multiple layers of flattened cells.
  ▫ As there are no blood vessels,
    nutrients and oxygen must reach
    these cells by diffusion from
    capillaries in lower layers.
Epidermis
 • Keratinocytes are cells in the epidermis that
   contain large amounts of keratin, a hard protein.
         These are the most abundant cells in the epidermis
         Forms a layer of dead, protective cells.
         Found on all exposed skin surfaces except eyes




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Epidermis
• Skin has different thicknesses,
  depending on where it is in the body.
  ▫ Thin Skin
     Covers most of the body
     Has four layers of keratinocytes

  ▫ Thick Skin
     Covers the palms of the hands and soles of the
      feet                                             Hyperkeratinosis: Excess
                                                       keratin production

     Has five layers of keratinocytes
 Life Cycle in the Epidermis
• Cells of the epidermis pass
  through five different stages
  as they grow and move
  outward.

• Cells begin at the base (near
  the dermis) and gradually
  move towards the outer
  surface.

• Each layer is called a
  stratum.
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Stratum Germinativum
 • The “generative” layer.
     ▫ Name comes from the presence of many germinative (stem)
        cells.
     ▫ Strongly attached to the dermis by desmosomes.
     ▫ Forms a strong bond between epidermis and dermis




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Stratum Germinativum
 • The Stratum Germinativum has a few specialized
   types of cells:
     ▫ Oval-shaped receptor cells are found in hairless areas of
       skin that specifically respond to touch.
     ▫ Melanocytes containing the pigment melanin.
         Melanin, along with carotene (orange pigment) creates different
          tones of skin color.




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Skin Color
 • Skin color is a
   polygenetic trait,
   meaning it is
   controlled by more
   than one gene.
 • Certain genes
   increase the size and
   number of
   melanocytes.



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Tanning
• Ultraviolet light in small doses helps the body
  produce Vitamin D.
• Large doses cause DNA damage, accelerates skin
  aging, and increases the risk of cancer.
 ▫ The skin responds by producing more melanin, which
   produces the darkened effect.
 ▫ Individuals with fair skin may not have enough
   melanocytes to achieve this protection.
• Tanning beds specifically produce ultraviolet
  light to induce the production of melanin.
 • Stratum Spinosum
     ▫ The “spiny layer”
     ▫ Cells continue to divide
       and produce keratin.




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• Stratum Granulosum
 ▫ The “grainy layer”
 ▫ Cells lose their nuclei, stop
   dividing and begin
   producing much more
   keratin.
 ▫ Keratin is a tough protein
   that is also found in the
   outer skin, fingernails, and
   hair.
• Stratum Lucidum
 ▫ The “clear layer”
 ▫ Found only in thick skin,
   not in thin skin.
 ▫ These cells are so far away
   from the blood supply that
   sufficient nutrients cannot
   diffuse to them, causing
   them to die.
• Stratum Corneum
 ▫ The “horn layer”
 ▫ This is the exposed
   surface of skin
    15 to 30 layers of
     keratinized cells, makes
     up about 75% of the
     epidermis.
    Water resistant.
    Shed and replaced every 2
     weeks.
Dust
• Indoor dust has three main components:
 ▫ Dead skin cells
 ▫ Dried feces and corpses of dust mites
    Microscopic arachnids that eat shed skin cells.
    Most likely cause of a dust allergy.
 ▫ Tiny fibers from clothing.
The Dermis
• Located between epidermis and subcutaneous
 layer.
• Anchors epidermal accessory structures (hair
 follicles, sweat glands)
• Has two components
 ▫ Outer papillary layer
 ▫ Deep reticular layer
 • Papillary Layer
     ▫ Consists of loose areolar tissue
     ▫ Contains smaller capillaries, tiny lymph glands, and
       sensory neurons
     ▫ This layer forms epidermal ridges (fingerprints)
         Purpose is not fully known.
         Hypotheses:
             Leftover from primate ancestors that gripped and climbed rough
              surfaces.
             Drains water quickly to maintain grip when wet.




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 • The Reticular Layer
     ▫ Consists of dense fibrous connective tissue
     ▫ Contains larger blood vessels, lymph vessels, and
       nerve fibers
     ▫ Contains collagen and elastic fibers




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 The Dermis
• The dermis contains two types of
  proteins:
    Collagen fibers:
      very strong, resist stretching but
       bend easily
      provide flexibility
    Elastic fibers:
      permit stretching and then recoil to
       original length
      limit the flexibility of collagen fibers
       to prevent damage to tissue
    Skin is flexible yet resistant.
The Dermis
     ▫ Collagen and elastic fibers in the dermis are
       arranged in parallel bundles that travel in a
       specific direction.
     ▫ The direction of these fibers influence how well a
       cut (or incision) will heal.
         A parallel cut will remain shut, heals well
         A cut across (right angle) pulls open and scars




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The Dermis
The Dermis
• The dermis contains all the arteries and veins
  that supply skin cells with nutrients and oxygen.

• Damage to blood vessels results in “black–and–
  blue” bruising as the hemoglobin and other cell
  components gradually break down and reabsorb.

• All nerves are also in this layer.
Tattoos
• Ink is injected into the
  upper dermis layer of the
  skin using a hollow needle.
• The dermis is used because
  the cells are more stable
  and do not continually
  move up, like the
  epidermis.
Tattoos and MRI
• Minimyth: Tattoo ink contains small amounts of metal ions. How
  will it be affected by an MRI (magnetic resonance image) scan?

• http://www.youtube.com/watch?v=AiE3in71YEo&noredirect=1
Figure 5–9 Dermal Circulation.
The Hypodermis
• The subcutaneous layer lies directly below
  the dermis.
 ▫ This layer is made of areolar and adipose tissues.
 ▫ The primary function of this layer is fat storage and an
   anchoring point for the rest of the skin.
    What is the fattiest part of chicken?
Accessory Structures
• Hair, hair follicles, sebaceous glands,
  sweat glands, and nails are all considered
  accessory structures.
 ▫ Each is located in the dermis.
 ▫ All project through the skin surface
Hair
• The human body is covered with hair, except
 ▫ Palms
 ▫ Soles
 ▫ Lips
• Functions of Hair
 ▫ Protects and insulates
 ▫ Guards openings against particles and insects
     (e.g. nasal passages)
 ▫ Is sensitive to very light touch
 Hair
• The Hair Follicle
 ▫ Is located deep in dermis
 ▫ Produces hair, which is made of
   nonliving keratin protein.
 ▫ Base is surrounded by sensory
   nerves.
    This makes hairs especially
     sensitive to detecting touch or
     motion.
Hair
• Accessory Structures of Hair
 ▫ Arrector pili
    Involuntary smooth muscle
    Causes hairs to stand up
    Produces “goose bumps”
    Considered a vestigial structure in humans.
Hair
• Which types of tissue
  are present in this
  slide?
Hair
• Hair Color
 ▫ Hair color is the result of two different types of
   melanin pigment produced by melanocytes at the
   hair root.
 ▫ One type of melanin causes red color, the other
   dark brown/black.
 ▫ Determined by genes.
Sebaceous Glands and Sweat Glands
• Exocrine Glands in Skin
 ▫ Sebaceous glands (oil glands)
    Produce oil, which helps to protect hair and skin.
    Help to control bacteria.
Sebaceous Glands and Sweat Glands




What types of tissue are present around sebaceous glands?
Sebaceous Glands and Sweat Glands
• Apocrine sweat glands
 ▫ Found in armpits and groin.
 ▫ Produce a sticky, cloudy secretion.
 ▫ Breaks down and releases odors.
 ▫ May contain pheromones.
 ▫ Purpose in humans not fully known.
Sebaceous Glands and Sweat Glands




What kinds of tissue are found lining apocrine sweat glands?
Sebaceous Glands and Sweat Glands
• Eccrine sweat glands
 ▫ Widely distributed on body surface, especially on the
   palms of hands and soles of the feet.
 ▫ Discharge water and salts directly onto skin surface
 ▫ Functions of eccrine sweat glands:
    Cools skin
    Excretes water and electrolytes (salt ions)
    Flushes microorganisms and harmful chemicals from skin
Sports Drinks and Sweat
Sebaceous Glands and Sweat Glands
• Other Integumentary Glands
 ▫ Mammary glands
    Produce milk

 ▫ Ceruminous glands
    Produce cerumen (earwax)
    Protect the eardrum
Nails
• Nails protect fingers and toes
 ▫ Made of dead cells packed with keratin

• Nail production
 ▫ Occurs in a deep epidermal fold near the bone
   called the nail root
Skin Anatomy




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            Sweat Pore          Hair




   Epidermis                    Stratum Corneum
                                Stratum Germinativum

                                Sebaceous Gland
     Dermis                     Arector Pili Muscle

                                Nerve
                                Hair Follicle
                                Nerve

  Hypodermis                    Adipose Tissue
(Subcutaneous))
                  Sweat Gland
Repair of the Integument
1. Bleeding occurs

2. Inflammation is
   triggered,
   increasing blood
   flow.
Repair of the Integument
3. A scab stabilizes and
   protects the wound.

4. Cells from the stratum
   germinativum
   surround the injured
   area.

5. White blood cells clean
   the area of bacteria and
   foreign substances.
Repair of the Integument
         6. Special cells
            called fibroblasts
            move in,
            producing scar
            tissue that fills
            in the area
            underneath the
            epidermis.
Skin Damage
• Sagging and wrinkles (reduced skin elasticity)
  are caused by
 ▫   Dehydration
 ▫   Age
 ▫   Hormonal changes
 ▫   UV exposure
• Stretch Marks
 ▫ Thickened tissue resulting from
   excessive stretching of skin due to:
      pregnancy
      weight gain
Effects of Aging
• Effects of aging include
  ▫ Thinning of the epidermis.
  ▫ Decreased melanin production.
  ▫ Decreased glandular activity (sweat and oil glands)
  ▫ Reduced blood supply, slower healing rate.
Epidermis
• Hydration
 ▫ Results from immersion in hypotonic solution
  (e.g., freshwater [osmosis])
 ▫ Causes swelling of epithelial cells, evident on the
  palms and soles
Skin Disorders
• Cyanosis
 ▫ Bluish skin tint
 ▫ Caused by severe reduction in
   blood flow or blood-oxygen
   levels.
• Jaundice
 ▫ Buildup of bile from the liver.
Vitamin D3 Deficiency
• Vitamin D3
 ▫ Epidermal cells produce
   vitamin D3 in the
   presence of UV radiation.
 ▫ Liver and kidneys convert
   vitamin D3 into a
   compound that helps
   absorption of calcium and
   phosphorus.
 ▫ Insufficient vitamin D3 can
   cause rickets.
Botox
• Botulinum toxin is one of the most powerful
  neurotoxins known.
• Produced by the bacteria Clostridium
  botulinium.
• Botox blocks a neurotransmitter that signals the
  contraction of muscles.
 ▫ This can diminish certain types of wrinkles (brow
   lines, frown lines)
• Side effects – can immobilize too much of the
  face, affecting facial expressions.
Botox
        • Effects will wear
          off; Injections
          must be repeated
          every 4-6 months.
Skin Infections
• Fungal Infections
 ▫ Athlete's foot
 ▫ Toenail fungus
 ▫ Ringworm
• Each is caused by related fungus species.
• Spread by contact, especially prevalent in dark,
  moist areas.
 ▫ Locker room, shower floors
 ▫ Shared footwear
• Only antifungal medications are effective (e.g.
  Lamisil)
Skin Infections
• Bacterial infections
  ▫ Impetigo
  ▫ Boils
  ▫ Staph infections
• Caused by a species of bacteria (Staphylococcus
  aureus) that colonizes in skin and begins
  producing toxins.
• Treated with antibiotics.
• Transmitted by contact.
• MRSA is a strain of Staph that is resistant to many
  antibiotics.
Viral Infections
• Chicken pox
  ▫ Infects epidermal cells, causing itching
    and raised bumps.
  ▫ Airborne and direct contact.
• Warts
  ▫ Causes the outer strata of the epidermis
    to overgrow.
  ▫ Spread by direct contact.
• Cold sores
  ▫ Caused by the herpes virus. Able to lay
    dormant within infected cells for an
    entire lifetime.
Viral Infections
• Viral infections are difficult to treat. The best
  course is usually prevention with an
  immunization shot.
Irritation
• Dermatitis
 ▫ An inflammation of the papillary layer of the dermis.
 ▫ Caused by infection, radiation, mechanical irritation,
   or chemicals (e.g., poison ivy)
 ▫ Characterized by itch or pain
• Itching
 ▫ Nerves begin firing when an irritant lands on the skin
   surface and is rubbed into the dermis.
 ▫ Scratching is meant to remove the irritant with the
   nails.
Acne
• Acne is the
  formation of pimples
  due to the blockage
  of sebaceous gland
  pores.
  ▫ Whiteheads are
    infected and black
    heads are not.
  ▫ The white pus is
    made up of white
    blood cells.
Skin Burns
• First-degree burns
 ▫ Only epidermis is damaged
 ▫ Skin is red and swollen
 ▫ Sun burns
• Second-degree burns
 ▫ Epidermis and upper dermis are damaged
 ▫ Skin is red with blisters
 ▫ Boiling water burns
• Third-degree burns
 ▫ Destroys all layers, including nerves and blood vessels.
 ▫ Burn is gray-white or black, often no pain felt.
Skin Cancer
• There are different types of skin cancer, classified
  based on the type of cell that grows
  uncontrollably:
  ▫ Basal cell carcinoma affects cells in the bottom
    stratum of the epidermis.
     The least malignant and most common type of skin
      cancer.
Skin Cancer
• Squamous cell carcinoma occurs in the
  second stratum (the “spiny” layer) of the
  epidermis.
• These tumors must be removed quickly, as they
  can metastasize through nearby lymph nodes
  and into the rest of the body.
• This form of cancer is usually caused by
  overexposure to the sun.
Skin Cancer
• Malignant melanoma is the most dangerous
  type of skin cancer.
• Caused by out of control growth in melanocytes.
• Can metastasize quickly to blood and lymph
  vessels.
• Can be differentiated from regular moles by the
  ABCD rule.
Skin Cancer
• A = Asymmetry
 ▫ Two sides of pigmented mole do not match
• B = Border irregularity
 ▫ Borders of mole are not smooth
• C = Color
 ▫ Different colors in pigmented area
• D = Diameter
 ▫ Spot is larger then 6 mm in diameter