Transcript The Immune System

The Immune System
• A complex group of defenses
found in the body that fight
against harmful substances and
pathogens
• Pathogen: infectious agent (or
germ) that causes disease or
illness in a host
Body Systems involved with
Immune System
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Skin
Respiratory System
Digestive System
Circulatory System
–Lymphatic System
First Line Defenses
• Skin: Barrier against pathogens
entering the body
• Perspiration and oil gland
secretions can make the skin a
bad environment for pathogens to
grow in
Internal First Line Defense
• Respiratory System
– Traps pathogens in cilia and mucus.
– Sneezing and coughing can get rid of pathogens.
• Digestive System
– Saliva-can kill bacteria.
– Stomach, pancreas, and liver-contain enzymes that
can destroy pathogens.
– Hydrochloric Acid-kills some bacteria and stops some
virus activity.
– Mucus in the digestive tract coats bacteria and keeps
it from sticking to other digestive organs.
Internal First Line Defense (con’t.)
• Circulatory System
– White Blood Cells
• Surround and digest foreign organisms and
chemicals
• Constantly patrol the body
– Inflammation
• Occurs when tissue is injured or becomes infected
– Signs of Inflammation: Redness, increase in
temperature, swelling and pain
• Increased blood flow to the area
Specific Immunity
• Antigen-a molecule that is foreign to your body.
– Lymphocytes respond to antigens in the body
• Killer T-cells: release enzymes that help destroy undesired
matter
• Helper T-cells: activate the immune system and stimulate
Blood cells to form antibodies
– Antibody-a protein made in response to a specific
antigen
• Makes the antigen useless and more easily caught by Killer
T-cells. Or the pathogen can be destroyed.
– Memory B cells-float in blood, waiting to respond to
the same pathogen at another time
Active vs. Passive Immunity
• Active Immunity:
– The body makes it own antibodies in response to an
antigen
– A Pathogen invades and multiplies, making the host
sick.
– The body makes antibodies that fight off antigens and
get the host well again.
– This is why you only get sick once from some
pathogens, such as Chicken Pox!
• Passive Immunity:
– When antibodies that have been produced in another
animal and are introduced into your body.
– Last less time that active immunity.
Vaccination
• Vaccine: a form of antigen that gives you
active immunity against a disease.
• Vaccination: the process of giving a
vaccine by injection or orally (by mouth).
• Helps reduce the risk of childhood disease
• Vaccine can prevent a disease but is not a
cure for someone who has contracted and
is suffering form a disease.
Tetanus
• Caused by a common soil bacterium.
• Can paralyze muscles.
– Sometimes called Lockjaw
• Puncture wounds and deep cuts can easily be
infected.
• Children are vaccinated early to build up
antibodies against the tetanus toxin.
• Tetanus vaccine also includes booster shots for
Diphtheria, a dangerous respiratory disease,
and Pertussis or Whooping Cough