Transcript Immune System Definition

Immune System
Mr. Bombick
7th Grade Science
Immune System Definition
• Immune system protects the body from
harmful viruses and organisms
(bacteria to parasites).
• Immune system protects the body from
foreign matter from molecules to
microscopic and macroscopic materials.
Initial Lines of Defense
• Not true immune responses
• Skin acts as a protective barrier to
foreign materials
• Respiratory tract clears foreign
materials with nasal filtration and
mucociliary movement helped by
sneezing and coughing
• Digestive tract starts to kill foreign
organisms with saliva and stomach
acid.
Second Line of Defense
• White blood cells attack foreign
organisms and bacteria
• Inflammatory response results as a way
of “recruiting” more white blood cells
• Interferon is a substance that is released
by some immune cells that prevent
some viruses from replicating
Third Line of Defense
• Antibody production by immune cells
• Antibodies are made in response to an antigen
(foreign proteins) found on a foreign substance or
invading organism
• T (from thymus) and B (from bone marrow) cells
involved in antibody production
• Certain T cells activate some B cells to produce
antibodies
• Combination of the antibody and antigen begins
various cellular processes to destroy the source of
the antigen
Immunity
• Immunity is the bodies resistance to a
disease causing organism or a harmful
substance
• The two basic types of immunity are
active immunity and passive
immunity
Active Immunity
• Results when antibody production
occurs in the same individual exposed
to an antigen
• Vaccination is an example of active
immunity
• Memory B cells can react to the
specific antigen years after the
vaccination (the memory B cells can
initiate the production of a large
amount of antibodies in a short period
of time
Immune Disorders
• Allergies are the result of antibodies formed
in response to various allergens (dust,
feathers, fur, pollen, or types of foods)
• Histamine is produced in the allergic
response (antihistamines help alleviate
some of the symptoms)
• Severe allergic responses can result in
anaphylactic shock
Immune Disorders (cont.)
• AIDS (Acquired Immune Deficiency
Syndrome) occurs in some individuals
exposed to HIV (Human Immunodeficiency
Virus)
• In these individuals the virus attacks a type
of T cell that results in decreased immune
function
• Decreased immune function eventually
leads to death