Download Basic Body Systems Unit 6 Immune System Lecture

Basic Body Systems
Unit 6 Immune System
Lecture
Pages 128-129 and 400-409
Chapter 5 and 17
Viruses
• A virus is technically not alive because it
doesn’t have any organelles inside it
• It also cannot live on its own, it has to have a
host
• A virus that infects bacteria is called a
bacteriophage
Virus Structure
• A virus is a piece of nucleic acid covered by an
outer coat of protein called a capsid
Reproduction in Viruses
• Viruses reproduce themselves inside of their
host
• The tail fibers of the virus attach the outside
of a cell
• Enzymes from the virus make a hole in the cell
and inject the virus’ genetic material inside
• Once inside of the host, the virus controls the
cell and reproduces itself
• Eventually there are so many new viruses
made that the host membrane ruptures
• All the viruses escape to attack new cells
• Usually the host cell dies at this point
• Some viruses , like HIV, don’t kill the host as
the new viruses are released
Dormant or Active
• Some viruses can live in your cells and go
dormant, or sleep
• Cold sores are causes by viruses that live in
your body
• When they are active you will see the sore
Classifying Viruses
• Viruses are classified based on which type of
organisms they infect
• There are plant viruses, animal, and bacteria
viruses
• Three ways viruses are classified:
• 1. Structure of the capsid
• 2. Does it contain DNA or RNA?
• 3. The way it reproduces
Defense Systems
• Pathogens are agents that cause diseases in
your body
• Your body is constantly fighting them off
Skin
• Skin is made of layers of cells that block the
entry of most pathogens
• This is your body’s first line of defense
Digestive System
• Bacteria and viruses enter the body through
your mouth
• Hydrochloric acid in your stomach helps kill
them
Respiratory System
• Bacteria and viruses can enter your body
through your nose
• Hair and mucous help trap them as you
breathe in
• Your body gets rid of them when you sneeze
and cough
Circulatory System
• White blood cells called phagocytes travel in
your bloodstream and attack bacteria and
viruses it meets
• The white blood cell eats them
The Lymphatic System
• White blood cells called lymphocytes hang out
in the tonsils, spleen, and various glands and
fight bacteria and viruses
The Immune System
• White blood cells called B and T cells send
signals to the immune system that a foreign
substance is present called antigens
• The immune system makes antibodies that
fight off these specific antigens
Resisting Disease
• Once the body has made specific antibodies,
they remain so the next time they are ready
when needed
• When you have these antibodies, your are
immune to that disease
Types of Immunity
• There are two types of immunity:
• 1. natural
• 2. acquired
Natural Immunity
• Natural immunity means you are born with
certain antibodies
Active Acquired Immunity
• Your body fights a disease because it has had
it once already and made the specific
antibodies to fight it
• Ex: chicken pox
T cells and B cells
• T cells work by calling the B cells into action
• T cells determine what antibody is needed,
and B cells help the phagocytes attack
Passive Acquired Immunity
• Instead of making the antibodies, your body
gets them from somewhere else
• Example: the flu shot
• This type of immunity does not last as long
Vaccines
• Vaccines are a serum injected into the body
that help it make antibodies to fight a specific
disease
• Ex: polio, measles, mumps
Germ Theory
• Diseases are caused by microscopic organisms
called germs
Identifying Germs
•
•
•
•
•
Cholera affects the small intestine
Lyme disease affects the skin, joints, heart
Salmonella affects the intestine
Tetanus affects the nerves
Tuberculosis affects the lungs, bone, and
organs
Spread of Bacterial Diseases
• Most diseases caused by bacteria are
contagious
• This means they can be spread from one
person to another
• Some diseases are spread by living organisms
Treating Disease
• Medicine and injections
• Antibiotics kill bacteria
Discovery of Antibiotics
• Penicillin, a type of mold, was the first
developed antibiotic
• Today they are produced from plants, animals,
bacteria, etc
How Antibiotics Work
• Antibiotics are made for a specific disease
• Allergic reactions can happen
Overuse of Antibiotics
• Antibiotics can kill both the harmful and the
useful bacteria in your body
• Bacteria can also become resistant to the
antibiotic and no longer work
Viral Diseases
• Different kinds of viruses attack different parts
of the body
• Viruses that cause warts only attack skin cells
Common Viral Diseases
• The common cold and the flu are both caused
by viruses
• Others include chicken pox, measles, mumps,
and hepatitis
HIV
• Human immunodeficiency virus (HIV) attacks a
persons immune system
• Causes acquired immune deficiency syndrome
(AIDS)
• AIDS kills white blood cells so you can’t fight
off diseases
Transmission of AIDS
• In order to get aids you must exchange blood
or body fluids from an infected person
• This can happen during sexual contact
• This can happen during a blood transfusion