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Non-specific Body Defenses:
The body has defenses in place to catch or prevent foreign
invaders from causing harm to the body. It is the body’s
first line of defense
Non-specific defenses fight/prevent pathogens:
Harmful or disease-causing microorganisms
There are 2 Main non-specific defenses:
3. The body’s first line of defense against the invasion of
pathogens involves 2 types of membranes: skin and mucous
membranes.
The second main nonspecific defense involves the use of cells
and chemicals. The main cell types are:
1. Phagocytes:
• The most abundant are neutrophils which release
the “killer chemical” defensins (oxidizing chemicals
similar to bleach)
•
The chief phagocytes are called macrophages. They
are originally wbc’s called monocytes. They become
active “big eaters when they leave the bloodstream
and enter the body tissues.
2nd nonspecific body defense (continued):
• We also have a special group of defensive cells that
can kill cancer cells and virus-infected cells. They
are called Natural killer cells (NK). They destroy
their target by releasing chemicals that damage the
cell’s membrane and disintegrates the nucleus.
Natural Killer video
When a wound or infection occurs, the body responds with an
inflammatory response. This draws the body’s defenses to
the foreign invader:
This response does 3 things:
1. Prevents the spread of disease to nearby tissue
2. Disposes of cell debris
3. Sets the stage for repair
THE INFLAMMATION RESPONSE:
1. The local capillaries dilate so more blood flows into the area.
Capillaries also become more permeable meaning: fluids can
flow into the surrounding tissue and cause swelling
Animation of inflammation response
THE INFLAMMATION RESPONSE:
2. Edema occurs, which is swelling due to influx of fluids to the
injured tissue. This might seem counterproductive but it
actually has several purposes:
a. It helps dilute harmful substances in the tissue
b. It delivers oxygen and nutrients to repair tissue
c. It brings in clotting proteins
3. More and more phagocytes invade the area, and so does a
group of plasma proteins called kininogen. It provides
chemicals that amplify inflammation.
4. If an infection is particularly stubborn, pus will develop in
the area: a mixture of dead or dying neutrophils, broken
down tissue cells and living and dead pathogens.
5. An important chemical is produced by body cells that have
been invaded by a virus. It inactivates or “interferes with”
the spread of viruses and is called interferons.
•
A low grade fever helps during an infection by: increasing
the rate of tissue repair and blocking the release of iron
and zinc from the liver, which viruses need in order to
survive.
Specific Body Defenses: When a foreign invader enters your
body, you create a specific body defense to prevent infection
from that pathogen a second time.
During specific body defenses you develop immunity.
Immunology: The study of the system that stalks and
eliminates pathogens that intrude the body.
The activity of the immune system, called the immune response
is different from the nonspecific body defenses:
•
•
•
It is not ready to react immediately to foreign invaders.
It must come in contact with a foreign substance called an
antigen and build up an immunity to that substance.
This involves developing special proteins that circulate in
the blood called antibodies.
Early experiments found three important capabilities of the
immune system:
1. Is antigen specific: it recognizes and is directed
against particular antigens.
2. Is systemic: It is not specific to an infected site.
3. Has a memory: After the first exposure, it recognizes
and attacks stronger with each additional exposure.
There are 2 main types of specific immunity:
1. Humoral immunity- the antibodies produced by B
lymphocytes bind to bacteria and toxins and viruses to
hamper activity. These antibodies also mark the
invader for attack by phagocytes or compliment.
2. Cellular immunity- specially developed cells called T
lymphocytes act against the invaders.
Key Players:
Macrophages
•help with the immune response by engulfing an antigen, cut it to
pieces and present it to the T cells to train them to recognize that
antigen.
•secrete substances that activate the T cells.
•Then the T cells in return release
chemicals that cause macrophages to
become huge phagocytes.
KEY PLAYERS:
B CELLS: primary player in humoral immunity
• Antibodies are produced by the B cells. The antibodies
produced are specific to that invader and are remembered
by B cells.
•
•
They also produce plasma cells which release antibodies as
well.
Plasma cells are not actually cells but are made from
proteins called gamma globulin found in the blood.
KEY PLAYERS:
T CELLS: primary player in cellular immunity; 3 types1. Helper T cells: activate other immune cells
2. Cytotoxic cells: attack and lyse infected cells
3. Supressor cells: stop the immune reponse when the
infection is finished.
Non-specific body defenses: deffight pathogens: defTwo types of non-specific defenses:
1. Membrane coverings:
2. Cells and Chemicals:
•Phagocytes: two ways cells can phagocytize foreign cells-
•NK cells: meanswhat they killhow they functionWhen a foreign substance enters a body tissue (wound or infection), the body’s first response is
INFLAMMATION. This attracts the non-specific body defenses to the site of infection.
Inflammation has 3 affects on the body:
1.
2.
3.
THE INFLAMMATION RESPONSE: How it works
1. Capillary action:
2. Edema (swelling):
3 reasons for swelling-
3. Phagocyte invasion:
4. Pus develops:
5. Interferons:
6. Low grade fever develops:
SPECIFIC BODY DEFENSES: developing immunity to a specific foreign invader to prevent infection
a second time.
immunologySpecific body defenses are different than non-specific defense because:
• It cannot• It must come into contact with• It must developEarly experiments show 3 unique features of specific body defenses:
1.
2.
3.
Two types of specific body defenses:
1. Humoral immunity:
2. Cellular immunity:
SPECIFIC BODY DEFENSES
MAIN PLAYERS:
MONOCYTES•Trains T cells (the main lymphocyte)- how?
•Activate T cells- how?
•Grow into large phagocytes- how?
B CELLS•Produce antibodies:
•Produce plasma cells:
T CELLS- three types:
1.
2.
3.