 immune
system
A combination of body defenses made up of the
cells, tissues, and organs that fight off
pathogens and disease
 immunity
Your body’s ability to resist the germs that cause
a particular disease
 inflammation
The body’s response to injury or disease, resulting
in a condition of swelling, pain, heat, and redness
 lymphatic
system
A secondary circulatory system that helps the body
fight pathogens and maintain its fluid balance
 lymphocytes
The white blood cells in the lymphatic system
 antigen
Any substance released by invading pathogens
 antibodies
Proteins that attach to antigens, keeping them from
harming the body
 vaccine
A preparation of dead or weakened pathogens that
causes the immune system to produce antibodies
In this lesson, you will learn to
 name the body’s first line of defense against pathogens.
 describe how the immune system functions.
 explain how antibodies protect the body.
 practice behaviors that keep your immune system healthy.
Sequencing
Draw a concept map that
shows different ways your
body works to defend itself
from pathogens entering
your body. Use Figure 18.2
as a guide.
Body’s
Defenses
What is a barrier?
Your Body Defends Itself
The Five Major Barriers
Tears
Saliva
cover and protect the
eyes from dust and
pathogens. As they
flow, tears carry
foreign material away
from the eye.
Washes germs away
from your teeth. It
contains chemicals
that kill pathogens
trying to enter through
your mouth.
Skin
provides a tough, outer
protective surface that
keeps pathogens from
entering your blood.
Mucous
Membranes
Stomach
Acid
are coated with a sticky
material called mucous
that traps pathogens
It kills many of the
pathogens that make it
past the saliva and
mucous membranes of
your mouth
Your Body Defends Itself
If a pathogen gets past one of the five major
barriers, your body’s immune system takes over.
1. Immune system A combination of body defenses made up
of the cells, tissues, and organs that fight off pathogens and
disease
Your Body Defends Itself
Your immune system has two main responses:
1) nonspecific response
2) specific response
Nonspecific Immune Response
A. The nonspecific response begins with inflammation.
Inflammation The body’s response to injury or disease, resulting in
a condition of swelling, pain, heat, and redness
Nonspecific Immune Response
With inflammation, the body starts producing a protein called
interferon to stimulate the body’s immune system.
The brain sends signals telling white blood cells to rush to the
affected area and destroy pathogens.
– Circulation slows down.
– If pathogens multiply and spread, your body temperature may rise
and cause a fever. A higher body temperature makes it harder for
pathogens to reproduce.
– A fever also signals the body to produce more white blood cells to
destroy the pathogens.
Specific Immune Response
Each specific response is customized to attack a particular
pathogen and its toxins.
Specific Immune Response
•Our
immune system can “recognize” pathogens it
has already battled.
Once our immune system creates a specific
response, cells from that response are ready to
attack when the pathogen reappears.
As a result, the second response is much quicker
than the first.
Your Body Defends Itself
•Together,
these responses provide immunity.
•What
is a trick from Survivor or Project Runway to
remember what immunity means?
Immunity- Your body’s ability to resist germs that
cause a particular disease
The Lymphatic System and Circulatory System
The circulatory system has blood as its main fluid
and the lymphatic system has lymph as its main
fluid.
The Lymphatic System
The two types of lymphocytes are B cells and T
cells.
Lymphocytes The white blood cells in the lymphatic system
White blood cells help to destroy the infection in the
body!
Lymphocytes
B cells form in the bone marrow.
T cells develop in the thymus gland.
Antibodies and Antigens
Lymphocytes react to antigens.
Antigen Any substance released by invading pathogens
•The immune system responds to antigens by
producing antibodies.
Antibodies Proteins that attach to antigens, keeping them
from harming the body
What does the word antibodies sound like?
What do antibiotics do to help us feel better?
Are antibodies the good or bad part of the
infection? (GOOD !)
B Cells
B cells produce a specific antibody for each specific
antigen.
T Cells
T cells either stimulate the production of B cells or attack
pathogens directly.
The two types of T cells are helper cells and killer cells.
– Helper T cells stimulate the production of B cells.
– Killer T cells attach to pathogens directly and destroy them.
Immunity
•Everyone
is born with some natural immunity.
•Breast
Feeding, if able, helps stimulate a baby’s
natural immunity
•Immunity
also develops when a vaccine is used.
What is a Vaccine?
A vaccination is a fancy word for a shot.
Vaccine A preparation of dead or weakened pathogens that
causes the immune system to provide antibodies
Immunity
To keep your body healthy, it is
important to keep vaccinations current.
Vaccines protect not only you but those
around you.
– Vaccines have been developed for many
diseases, such as polio, measles, and
chicken pox.
– Some vaccinations, such as those for
hepatitis B, must be given in a series
over a span of a few months.
– Other vaccinations, such as the tetanus
shot, must be given repeatedly during
your lifetime.
Lesson 2 Review
What I Learned
Vocabulary Define the term antigen. Name two types
of white blood cells your immune system produces to
fight antigens.
Lesson 2 Review
What I Learned
Recall What is the lymphatic system? How does it
protect your body against disease?
Lesson 2 Review
What I Learned
Explain What is the body’s first line of defense against
pathogens?
Lesson 2 Review
Thinking Critically
Analyze How does a fever help fight an infection?
Lesson 2 Review
Thinking Critically
Evaluate How do vaccines help protect the health of
the community?
End of
Chapter 18
Communicable
Diseases
Lesson 2
The Body’s Defenses
Against Infection
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