Download The Immune System

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The immune system
The Fortress Analogy
1st Line of Defense- Skin and mucous
(The outer wall)
 Skin:
 Made
up of 3 layers:
-Epidermis
-Dermis
-Hypodermis
 Includes
hair and
sweat glands
Function: Blocks most microbes
from entering the body.
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Mucous Membranes &
Secretions
(Inner Wall)

Mucous Membranes- Line all the major entry ways
into the body. i.e. esophagus, anus, nose…
-Usually are acidic to kill incoming bacteria.

Secretions such as saliva and tears contain
enzymes which digest the bacteria’s cell wall.

Cilia sweep mucous and move pathogens out

Helpful bacteria protect you from harmful bacteria
Function: Kill any microbes that
get past the skin.
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2nd Line of DefenseInflammation

White Blood Cells release histamines when
they come across enemy antigens.

Histamines increase the permeability of
capillaries.

(Capillaries are tiny blood vessels that run
throughout your entire body.)

WBC’s are sent throughout the body using
capillaries and the war begins.

WBC release chemicals that create a fever
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Histamines

Histamines act like a look out or scout.

Sound the alarm.

Clear the way for the soldiers (blood vessels)

Trigger immediate responses (tears, saliva, goosebumps)

Sometimes over-react to allergens causing itchy, watery eyes and
nose.
Two road systems

Lymphatic systemDucts and nodes contain and
transport white blood cells.
Acts as a collection system for
fluids in the body.
-Nodes swell when bacteria are
present.

Blood
White blood cells, lymphocytes,
histamines and nutrients are
transported through the blood.

Gathers fluid and white blood
cells from the lymph system.
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Terms to know:

Antigen-a molecule that elicits an immune response.
(Carried by bacteria)

Antibody- a protein found in blood plasma that attaches to
certain antigens and counter-acts it.

Phagocytosis- process of “cell eating”- done by white blood
cells.
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ARMY- phagocytes

White blood cells

Phagocytes destroy invading bacteria by engulfing it and
digesting it

Phago-Eating

Cyto-Cell

Find cells that have been marked by the B-lymphocytes
The Marines- Specialized Cells
B-lymphocytes and T-lymphocytes

Every bacteria produces their own identifying
antigen (Like a uniform)

B-cells- Mark bacteria with an antibody

T-cells- Kill infected or damaged cells

B and T cells make memory cells

Memory cells- help your body remember the
infection so your body is prepared the next time
you are infected.
Function: Destroy invading bacteria and
remember how to stop it.
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Vaccines

Immunity is built up against specific invaders.

Vaccines-made of a harmless variant of a disease causing
microbe.

Lymphocytes create memory cells against the specific
bacteria or virus.

Can get sick from vaccines if your immune system is weak.
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REVIEW
1st Line of Defense _______________
2nd Line of Defense______________
What causes the body to be aware of invasion?__________________.
What kind of cells are general killers?
_____________________
What kind of cells are specific in what they target?_________________
What cells help your body to remember the bacteria for the next
time?_______________