The Immune System and Disease

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The Immune System and Disease

• Copy everything in RED

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Diseases

• Disease any change, other than injury, that
  disrupts the normal functions of the body
• Diseases can be inherited (ex. Hemophilia)
• Diseases can be caused by materials in the
  environment (ex. Cigarette smoke)
• Diseases can be produced by agents (ex. Bacteria,
  viruses, fungi) pathogens
• Pathogens sickness-makers
• Diseases caused by pathogens infectious
  diseases, because they enter, or infect, the body

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Agents of Disease

• The human body provides great conditions for
  pathogenic growth
• You have many different microorganisms living in
  your body that are actually harmless or
  beneficial
• However, some microorganisms are dangerous
• Some bacteria break down body tissues and others
  release toxins (poisons)
• Some protists, fungi, and worms are parasites
  that live inside you and use up your nutrients or
  destroy blood/nerve cells
• Viruses are nonliving pathogens that use a host
  cell to make copies of the virus and destroy
  other cells

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Spreading Infectious Diseases

• Infectious diseases are spread
• From person to person coughing, sneezing, or
  physical contact
• Common cold, mumps, measles, influenza, STDs
  (AIDS), meningitis, athletes foot
• Contaminated water and/or food
• Cholera, dysentery, E.coli infection,
  salmonellosis
• Vectors infected animals (ticks/mosquitoes)
• Lyme disease, malaria, West Nile virus, rabies

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Figure 403 Pathogens and Disease
Section 40-1
Agent That Causes Disease
Method of Transmission
Pathogen Types
Disease
Common cold
Viruses
Influenza
Chicken pox
Measles
Bacteria
Tuberculosis
Meningitis
Cholera
Tetanus
Protists
African sleeping sickness
Malaria
Amoebic dysentery
Worms
Schistosomiasis
Beef tapeworm
Fungi
Athletes foot
Ringworm
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Fighting Infectious Diseases

• Drugs have been developed to use against
  pathogens
• Antibiotics chemicals that kill bacteria
  without harming the cells of humans or animals
• Penicillin interferes with the synthesis of
  cells walls by Eubacteria (breaks down
  peptidoglycan in their cell walls)
• Streptomycin interferes with bacterial growth
  by blocking protein synthesis in ribosomes
• Antivirals inhibit the ability of viruses to
  invade cells or multiply inside cells

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The Immune System

• A series of defenses that guard against diseases
  bodys protection
• Nonspecific defenses walls of the immune
  system keeping everything out
• Specific defenses security guards identifying
  and inhibiting pathogens

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Nonspecific Defenses

• Skin most important nonspecific defense
• Physical barrier
• Acidic environment on surface kills bacteria
• Mucus, sweat, tears and saliva
• Traps pathogens and removes them from the body by
  cilia or destroys them using the enzyme lysozyme,
  which breaks down cell walls
• Inflammatory response reaction to tissue damage
  caused by injury or infection
• Blood vessels around wound expand, white blood
  cells enter infected tissue and phagocytes
  (special WBCs) engulf and destroy bacteria,
  tissue becomes swollen and painful, body
  temperature ingrowth and increase circulation and
  activity of WBCs
• Interferon proteins that interfere with the
  virus
• creases (fever) to slow pathogen Proteins
  released by virus-infected cells to help other
  cells resist viral infection by inhibiting viral
  protein synthesis, blocking viral replication

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Specific Defenses

• Pathogen any disease causing agent
• Antigen a substance that triggers the immune
  response (organic molecules on the surface of
  pathogens)
• Antigens are chemicals present on the surface of
  viruses, bacteria, pollen grains etc.
• Antibody protein that helps destroy pathogens
  by binding to antigen and attracting phagocytes
  to engulf and destroy them

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Humoral Immunity

• Immunity against pathogens in the body fluids
  (blood/lymph)
• Immunity produced by lymphocytes (type of WBC)
• B lymphocytes (B cells) produce antibodies to
  mark pathogens and prevent future infections

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Cell-mediated Immunity

• Immunity that relies on lymphocytes (cells)
• Killer T cells (cytotoxic T cells) can attack
  infected cells and destroy their cell membranes
• Killer T cells are what make organ transplants
  difficult, because they see the new organ as
  foreign and begin to attack it rejection.

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Permanent Immunity

• People that survived infectious diseases, never
  developed the same disease again
• Memory B and T cells remain capable of producing
  specific antibodies to that pathogen, ensuring
  the disease never gets a chance to develop again

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Active Immunity

• An immediate active immune response against the
  pathogen in a vaccine
• Vaccination injection of a weakened or mild
  form of a pathogen to produce immunity
• Prevents serious human diseases by stimulating
  the immune system to create plasma cells capable
  of producing the specific antibodies for another
  possible infection
• Active Immunity lasts long term (permanent)

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Passive Immunity

• Antibodies produced by other animals for a
  pathogen are injected into the bloodstream
• The antibodies will produce passive immunity
  against a pathogen as long as they remain in
  circulation (several weeks)
• Antibodies from the mother are passed to the
  fetus through the placenta or to the infant in
  the mothers milk maternal immunity
• The antibodies will produce passive immunity
  against most infectious diseases for the first
  few months of life or longer if breast-fed

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Immune System Disorders

• Although the immune system defends the body from
  potential pathogens, sometimes disorders occur
• The immune system may overreact to an antigen,
  producing discomfort or disease
• The cellular nature of the immune response is a
  potential weak point

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Allergies

• Overreaction of the immune system
• Allergies occur when antigens from allergens
  (pollen, dust, dust mites) bind to mast cells
  (type of immune cell common in nasal passages)
• Activated mast cells release chemicals
  histamines, which increase the flow of blood and
  fluids to the surrounding area (sneezing, runny
  eyes/nose, etc)
• Antihistamines drugs used to reduce allergy
  symptoms by counteracting the effects of
  histamines
• Asthma allergic reaction where smooth muscle
  contractions reduce the size of air passageways
  in the lungs making breathing difficult

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Autoimmune Disease

• The immune system has the ability to distinguish
  self from nonself
• The immune system makes a mistake and attacks the
  bodys own cells (it attacks itself)
• Juvenile-onset diabetes (immune system attacks
  insulin-producing cells in pancreas)
• Myasthenia gravis (attacks neuromuscular
  junctions)
• Multiple Sclerosis (destruction of myelin sheath
  attacks nervous system)
• Lupus (attacks cells and tissues resulting in
  inflammation and tissue damage heart, joints,
  skin, lungs, blood vessels, liver, kidneys and
  nervous system)

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AIDS

• Acquired Immune Deficiency Syndrome (AIDS) when
  cells of the immune system are weakened by
  infection
• Caused by HIV (human immunodeficiency virus) and
  spread by contact with body fluids (drug needles,
  unprotected sexual intercourse, breast milk,
  blood during birth, blood transfusions)
• HIV attaches and destroys most helper T cells, so
  body is more susceptible to infections
• People DO NOT die from HIV/AIDS, they die from
  the infections they get because the HIV virus has
  left their immune system unable to respond to the
  infections

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Cancer

• Cancer is caused by defects in the genes that
  regulate cell growth and division
• Inherited genes
• Viruses interfere with cell cycle (mitosis)
• Ex. Human papilloma virus (HPV an STD) can lead
  to cervical cancer or genital warts (non
  cancerous)
• Radiation causes mutations in DNA
• Ex. X-rays, nuclear radiation, sunlight (UV Rays)
• Chemicals cause mutations in DNA
• Carcinogens chemicals that cause cancer
• Ex. Chloroform and benzene (industrial solvents
  used in production of drugs, plastics and
  synthetic rubber, small component in gasoline),
  cigarette smoke

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