Download Chapter 40 – Body`s Defense

Ch. 40 – The Body’s Defenses
• What does your body need to defend
itself from?
Answer – Pathogens
• Take a look at the different pathogens
that exist....
• You come into contact with hundreds of
pathogens each day. However, most people
get sick only 1-3 times a year!
• What are some first line defenses of your
body that prevent you from getting sick?
A. First Line of Nonspecific Defenses…
1. Skin (when unbroken) keeps out many
pathogens.
2. Stomach Acid kills pathogens in food.
3. Mucous that lines respiratory
passages, and trachea trap pathogens
before they reach lungs.
4. Cilia are on the cells of respiratory
tract continually sweep dust and
pathogens up.
B. Second Line of Nonspecific Defenses….
1. Inflammatory Response (see handout)
Injury like a cut or scrape causes this
2. Fever
is helpful because pathogens don’t
grow well in high temperatures.
3. Interferon
Protein produced by cells infected
with viruses. This protein causes
nearby uninfected cells to produce
enzymes to block the reproduction of
the virus.
C. Third Line of Specific Defenses….
-This is called an Immune Response.
1. Recognizing Pathogens
Marker Proteins
-All cells have _____________
which advertise their cell type.
Human
Muscle
Cell
Pathogen
-WBCs recognize pathogens because
they have “non-self” marker
proteins…. foreign antigens
2. Destroying Pathogens
-WBCs called Phagocytes & Lymphocytes…
1. Phagocytes - Ingest pathogens
2. Lymphocytes (Two Types):
a. T-Cells
-Destroy body cells infected w/pathogens
b. B-Cells
-Produce antibodies that destroy
pathogens
Pathogen
-Antibodies attach to and destroy
foreign antigens.
-Antibodies are specific…there is a
different antibody for every foreign
antigen.
*What do you think would happen if the
same pathogen enters the body again?
Answer: Memory WBCs remember the
pathogen and stimulate the B cells to
make the antibodies that were made
the first time the pathogen was in the
body. The antibodies destroy the
pathogen immediately and you don’t get
sick