Uploaded by Barbara Tucker

Chapter 6- Microorganisms and the immune system

Nervous system questions in short
answer booklet 14-26
Answers should be a few words
Will review in class tomorrow
Immune system questions in short
answer booklet 36-52, 101, 105
Answers should be a few words
Will review in class tomorrow
Wednesday night
Skeletal and muscle questions in
short answer booklet 92-103
Bring in red and blue pencils
4-Unit 4
AIM: How does the
immune system help
maintain homeostasis in
the human body?
What is Immunity?
• Immunity – the ability of the
body to fight infection
through the production of
cells that kill/stop foreign
substances or cells.
What is disease?
• Disease is defined as “an illness or condition
that prevents the body from functioning
Communicable Diseases
Certain germs cause communicable
diseases. These are contagious diseases.
A widespread outbreak of a disease is called
an epidemic.
A non-communicable disease is a disease
that cannot be passed from one person to
another like heart disease, diabetes and
• Pathogens are germs. There are
three different kinds of
pathogens. They are bacteria,
viruses, and fungi.
HOMEWORK Tuesday night
Immune system questions in short
answer booklet 36-52, 101, 105
Answers should be a few words
Will review in class tomorrow
What is a bacteria?
• Bacteria are single
celled prokaryotic cells.
There is no nucleus or
organelles. There is a
single loop of DNA.
• They are alive. They
can be killed with
How do bacteria reproduce?
• Bacteria reproduce by
making exact copies of
themselves. They grow
• Because they are alive,
they can be killed. That
is where antibiotics
come in.
How do antibiotics work?
 An antibiotic is
a selective poison.
 Each different type of
antibiotic affects
different bacteria in
different ways.
 Some affect the cell
membrane of the
 Some antibiotics work
on killing the
organelles in the
• Antibiotic resistant bacteria
 Superbugs are bacteria that are resistant to several
different antibiotics.
 Bacteria can become resistant to antibiotics by mutating
(changing) their genes after being in contact with an
antibiotic. These changes allow the bacteria to survive or
‘resist’ the antibiotic.
• Viruses are not alive.
They get into living cells
and take over the DNA
of the cell.
• A virus particle is made
of the following:
• 1. Nucleic acid - set of
genetic instructions
• 2. Coat of protein that
protects the genetic
How viruses reproduce
1.A virus particle attaches to a
host cell.
2. It releases its genetic
instructions into the host cell.
3.The injected genetic material
recruits the host cell's
4.The enzymes make parts for
more new virus particles.
5.The new particles assemble
the parts into new viruses.
6.The new particles break free
from the host cell and go into
other cells.
“How Are Diseases Transmitted
 Many ways... they
can travel through the
air, in contaminated
food or water, or
infected body fluids
like blood.
First line of defense-your skin-9
 The epidermis is a block
for a lot of germs.
 The skin has chemicals
that kill some bacteria,
but if there is an open
wound or cut, the germs
can still get in.
2nd line of defense
 Tears and saliva
have chemicals in
them that break
down cell walls of
some bacteria and
 Acid in your
stomach also breaks
down germs.
First and second lines of defense-11
stomach acid
low pH kills
mucus linings
traps dirt and
The Immune System-12
If a bacteria or virus
gets pasts these
defenses, our body
has a built in system
called the immune
system- to find and
kill microbes.
The soldiers of the
immune system are
different kinds of
white blood cells.
Where are white blood cells
• White blood cells
travel around in the
blood vessels all over
the body.
• White and red blood
cells are in blood.
Blood has plasma, white blood cells and
red blood cells
 Blood is actually made up
of several different kinds
of cells.
 To separate the different
parts in the blood, it is
placed in a special spinner
called a centrifuge. When
the blood is spun around,
the red blood cells - the
heaviest part of the blood go to the bottom of the
 After it is separated, the
white blood cells are in
the middle.
 The red blood cells are
on the bottom.
 The plasma, which
contains digested food
and vitamins, is on the
Lymphatic system
 WBCs travel in the
blood vessels.
 Other WBCs are in the
lymphatic system.
This system is made
up of thin tubes,
called lymph vessels
that branch
throughout all parts of
the body. Along this
network of vessels are
groups of small, beanshaped organs called
lymph nodes.
Lymph nodes-17
 There are more than
100 tiny, oval structures
called lymph nodes.
The lymph nodes
SEND OUT the white
blood cells to destroy
germs. There are
different types of white
blood cells that have
different jobs.
What triggers the Immune
There are special
markers on the
outside of the
bacteria or virus that
identify it. The
markers also tell your
body if it doesn’t
belong and triggers
an immune response.
These markers are
called antigens.
Antigens and Antibodies
Antigens are specific proteins that are found on the
surface of a pathogen. The surface of every germ has a
unique design. This is their identity card to the body.
When an antigen enters the body, the immune system
produces antibodies against it.
It is like a battle with the army (antibody) fighting off
the invader (antigen).
The invader is the
The army is the
white blood cells.
B Lymphocytes are
one kind of white
blood cell. They
look like this at
first. They have no
specific shape.
B-Lymphocytes are one kind of white
blood cell.
• B-Lymphocytes change
form so they can make
antibodies that attach
themselves to the antigen
and fit exactly like a puzzle.
• The antibodies are always Y shaped.
attaches to
the antigen.
It can’t go
and it can’t
 Once
Another kind of white blood cell is a
• Macrophages are the
biggest blood cells.
They destroy foreign
(antigens) and
gobble them up.
• When the antibody binds to the antigen, it
stops its movement. Then, macrophages
can come to gobble it up. Extra antibodies
remain in the body as memory cells.
A Pathogen Gets into Your Body
(Memory antibodies) stay in body that are
already made and can quickly go to attach
to THAT PATHOGEN the next time it gets
in your body!!!
Why do you think this baby
is getting a shot in his arm?
He is getting a Vaccination
A vaccination is an injection of a
weakened form of the actual
antigen that causes the disease.
The injection is too weak to make
you sick, but your lymphocytes
will make antibodies for it.
Active or Passive Immunity
•If you actually get an infectious disease
(like Chicken Pox), antibodies are
automatically produced. Another name for
these antibodies is MEMORY cells. They
stay in the body and will remember if
another chicken pox germ enters your
body. That is active immunity.
•Passive Immunity- getting the immunity
by means of a vaccination or through the
mother during pregnancy.
Immune System Disorders
 Allergy – the body does not
recognize ordinary things like
pollen, shrimp, or peanuts and the
immune system reacts.
 Transplant rejection occurs when the
body recognizes the organ as foreign
and mounts an immune response
against it. This is more likely to
happen if the organ comes from a
different person or not a relative.
 Immunosuppressant drugs –
suppress the immune system so it
does not attack the transplanted
Autoimmune Disease
The immune system can make a mistake
and attack its own body cells
 Examples of autoimmune diseases are
Crohns’s disease and ulcerative colitis.
AIDS is a virus that attacks the immune system of the
person who has the disease. If a person becomes
infected with AIDS, they will find it harder to fight off
infections and diseases. The virus takes T lymphocyte
cells and turns them into AIDs viruses. Those T
lymphocyte cells used to be fighter immune cells.
Over time, most helper T-Cells are killed. The body can’t
fight infections.
It is spread by contact with infected blood and other
body fluids.
A problem with the controls that regulate
cell growth and division. Cells grow and
divide uncontrollably, forming a tumor. It
can be caused by genes, certain
chemicals, or random mutations.
3 Types: A, B, O
If a person is given the wrong blood type the body
recognizes it as foreign and will produce antibodies to
fight it. This results in the clumping of blood which will
clog capillaries and result in death.