The Skin and Immune System

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The Skin and Immune System
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Section Outline
Section 36-3
363 The Integumentary System The
Skin 1. Epidermis 2. Dermis 3. Skin Cancer
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Roles of the Skin

• The skin has four roles
• It acts as a barrier against infection and injury
• It helps to regulate body temperature
• It removes waste products from the body
• Provides protection against UV radiation from the
  sun
• It also serves as a way through which sensations
  are transmitted to the nervous system

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Layers of the Skin

• Made of two main layers
• Epidermis outer layer
• The outer layer consists of dead skin cells
• The inner layer is made of living cells
• These undergo rapid cell division, constantly
  making new cells and pushing older cells to the
  surface
• Also contains melanin (pigment)
• Dermis contains collagen fibers, blood vessels,
  nerve endings, glands, smooth muscle and hair
  follicles

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Figure 36-13 The Structure of Skin
Section 36-3
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Disorder of the Skin

• Skin cancer
• Excessive exposure to UV radiation can lead to an
  abnormal growth of cells in the skin

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Section Outline
Section 40-2

• 402 The Immune System
• A. Nonspecific Defenses
• 1. First Line of Defense
• 2. Second Line of Defense
• B. Specific Defenses
• 1. Humoral Immunity
• 2. Cell-Mediated Immunity
• C. Acquired Immunity
• 1. Active Immunity
• Passive Immunity
• D. Diseases of the Immune System

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The Immune System

• The bodys primary defense mechanism
• May destroy invaders by engulfing them by special
  cells or by marking them for destruction and
  elimination
• Functions by being able to recognize proteins on
  the surface of cells
• It can distinguish between self and non-self
• The non-self, or invading foreign proteins are
  referred to as antigens

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Nonspecific vs. Specific

• Two types of defense mechanisms
• Non-specific physical and chemical barriers
• 1st line of defense - Keep pathogens out of your
  body
• Done by skin, mucous, sweat and tears
• 2nd line of defense inflammatory response
• If pathogens do enter your body, phagocytic white
  blood cells move into the area to destroy the
  bacteria
• The immune system also releases a chemical that
  increases your body temperature

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Figure 407 The Inflammatory Response
Section 40-2
Wound
Skin
Phagocytes move into the area and engulf the
bacteria and cell debris
Bacteria enter the wound
Capillary
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Specific Defense

• A specific defense against a pathogen is called
  an immune response
• Pathogens that trigger this response are called
  antigens
• These may be viruses, bacteria, fungi, parasites
• The immune response attacks the particular
  pathogen with a response designed especially for
  it
• Two types of wbcs that recognize specific
  antigens
• B cells pathogens and antigens in body fluids
• T cells pathogens and antigens inside living
  cells

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Primary and Secondary Immune Responses
Section 40-2
Interval between exposures
First exposure
Second exposure
Antibody Concentration
Time
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Acquired Immunity

• Two types of acquired immunity
• Active appears after exposure to an antigen
• May be natural (you get sick)
• May be artificial (through vaccination)
• Vaccine injection of a weakened form of an
  antigen to produce an immune response
• Passive receiving antibodies to fight off an
  infection
• May be natural antibodies are passed to a baby
  through the placenta and through breast milk
• May be artificial vaccines may contain
  antibodies to protect and prevent disease

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Section Outline
Section 40-3

• 403 Immune System Disorders
• A. Allergies
• Autoimmune Diseases
• HIV and AIDS

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Allergies

• An overreaction of the immune system
• Allergy causing antigens enter the body and
  attach themselves to certain white blood cells
• Produce chemicals called histamines
• Asthma a chronic respiratory disease where the
  air passages become narrower than normal, causing
  wheezing, coughing and difficulty breathing
• May be treated with medications that relieve the
  symptoms of asthma

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Autoimmune Disorders

• The immune system has the ability to recognize
  self and non-self
• When the immune system makes a mistake and
  attacks its own cells, it produces an autoimmune
  disease
• Examples
• Type I diabetes insulin-producing cells of the
  pancreas are destroyed
• Multiple sclerosis antibodies destroy the
  functions of the neurons in the brain and spinal
  cord

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HIV and AIDS

• AIDS is an autoimmune disease that results from
  infection with HIV
• Normally healthy patients die from microorganisms
  that dont normally cause disease, from extremely
  rare forms of cancers and pneumonia and from
  pathogens that healthy people can normally fight
  off
• HIV a virus that can evade the defenses of the
  immune system and attacks key cells in the immune
  system

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Transmission and Prevention of HIV

• Transmitted through bodily fluids
• Through any form of sexual intercourse
• Through shared needles that are contaminated with
  infected blood
• Through contact with blood or blood products
• From infected mother to child, through pregnancy,
  birth and/or breast feeding