Download L2 The body`s Natural Defenses

L2: The Body’s Natural Defenses
BIG QUESTION: What is the body’s first line of defense against bacteria
and germs?
WARM-UP: Make a list of all the ways in which a germ or foreign
particle might get into the body. (p. 54 of Journal – title “Body’s Natural
Defenses”)
Lesson Objectives: SWBAT
•Describe the body’s natural defenses
•Explain how each defense protects the body
•Create a specialized germ that would be able to penetrate these
defenses.
L2: The Body’s Natural Defenses
The human body has natural defenses which prevent foreign particles
and germs from entering the body.
1. How can germs and foreign particles enter the body? Share your
answers.
FORGET IT!
WE NEED TO FIND A WAY
INTO THE BODY!
L2: The Body’s Natural Defenses
The human body has natural defenses which prevent foreign particles
and germs from entering the body.
1. How can germs and foreign particles enter the body? Share your
answers.
• The mouth and nose
• Any open hole,
including the ears, anus
• Sores and cuts
• Exposed tissue from
piercings
• The eyes
Ahh, I see an opening!
Oh Boy!
Me and my
big mouth!
L2: The Body’s Natural Defenses
There are 6 natural body defenses which help defend our body from
foreign particles these include the SKIN, TEARS, SALIVA, MUCUS, HAIR
and STOMACH ACID.
The skin is
my main
barrier
L2: The Body’s Natural Defenses
THE SKIN
The SKIN this is the major barrier to foreign particles. Its outer layer is
tough, it also contains sebaceous glands which secrete oil (sebum)
which help kill bacteria.
The skin is
the body’s
largest
organ
L2: The Body’s Natural Defenses
THE SKIN
The surface of the skin is
constantly being renewed, the top
layer is replaced about every 27
days.
The oil glands, sometimes referred
to as the sebaceous glands release
oil. This oil (sebum) contains some
antibacterial qualities, killing
bacteria.
The skin also contains special cells
called “Langerhans Cells”, which
detect foreign particles, they then
present these particles (their
antigens) to the immune system
which will decide what to do.
L2: The Body’s Natural Defenses
TEARS
The EYES, although they are not holes, do allow foreign particles or
bacteria to enter the body. The eyes are therefore protected by TEARS.
If you ever get something in your eye you might notice that your eye
starts to water, this is a natural defense mechanism.
My Eyes
are burning
Tears produced
here
L2: The Body’s Natural Defenses
TEARS
The tears, contain a chemical called Lysozyme, this chemical kills
microorganisms (small living things). This process is sometimes
accompanied with the release of mucus, which can capture foreign
particles, the mucus then hardens and accumulates in the corner of
your eye.
QUICK RUN!
Tears produced
here
SHE HAS GOT TEARS!
L2: The Body’s Natural Defenses
SALIVA
Your mouth is huge , some people’s mouths are bigger than others!!
The facts is that the mouth is a great way for bacteria and other germs
to enter the body. Luckily for us we have SALIVA.
SALIVA: is the liquid that is
produced naturally in our
mouth. It plays an important
role in the digestion of food,
but also in killing germs.
These germs
make my
mouth water
L2: The Body’s Natural Defenses
SALIVA
SALIVA contains the same chemical that is found in tears, Lysozyme. If
something enters our mouth the Lysozyme chemicals get to work
destroying the germs.
Lysozyme in saliva
I am out of
here!
HELP ME! I’m
MELTING…..
L2: The Body’s Natural Defenses
MUCUS
MUCUS is that gross sticky stuff that runs from your nose.
MUCUS: Is found in the nose and
respiratory system. It sticks to
foreign particles and microbes.
Some mucus contains white
blood cells which can call for
back up or handle the infection
on the spot.
Stay away I
have got
mucus in my
nose!
MUCUS
In the respiratory system, the mucus is secreted from tiny structures
called Goblet cells, which are located in the lining of the trachea (wind
pipe).
Mucus secreted by
goblet cell
Goblet Cell
MUCUS
The mucus is carried to the top of the trachea by a column of ciliated
epithelia.
Column of Ciliated Epithelia
Goblet Cell
Trachea
ZOOM
Mucus secreted by
goblet cell
Cilia moves mucus
away from lungs
Mucus traps dust
particles and it is
swept to the top of
the trachea
MUCUS
The cilia beat back and forth carrying the mucus and germs upwards.
dust
germs
mucus
cilia
Ciliated
epithelium
Mucus, germs and dust moves
along like a conveyor belt
MUCUS
If mucus was not produced by the goblet cells dust, germs and other
particles might become lodged within the airways, which could result in
an infection.
Foreign Bodies
Goblet Cell
COUGH
COUGH
COUGH
HAIR
L2: The Body’s Natural Defenses
HAIR: Tiny hairs in the nose, ear, and pubic area can help keep
unwanted particles out of the body. They are also a great place to catch
mucus which might contain foreign particles.
NOSE HAIR
You are no
match for my
nose hair!
That nose
hair is scary!!
Lets think of
another plan!
L2: The Body’s Natural Defenses
STOMACH ACID
STOMACH ACID: The stomach contains Hydrochloric Acid which kills
microorganisms. If you eat something that contains bacteria, or other
microorganism the acid should destroy it.
My acid will
destroy you
little germ!
ACID
L2 The body’s Natural Defenses: ACTIVITY
1. The body has many natural defenses, however the fact that we get sick
means that these defenses are not 100% effective. Using a decision tree*
(next slide), Imagine that you were a germ, what would be the best
way to enter the body. Create 3 solutions, for each solution list the
pros and cons, then based on your evidence explain which is the best
solution and why. .
2. If you could remove one natural defense to make it easier for germs to
enter the body, which defense would it be and why? Include explain and
support your argument with evidence
3. Design the ultimate germ. Create a sketch of the ultimate germ,
annotate your sketch to explain what features it has to help it get
past the body’s natural defenses. You may draw your own or use the
templates below to help you.
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THE DECISION TREE
BEST SOLUTION and WHY:
SOLUTION #2
SOLUTION #3
PROS
PROS
PROS
CONS
CONS
CONS
STATE THE PROBLEM:
Biologyguy ©
SOLUTION #!
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