# data[].attributes.body
The immune system protects the body from worms, germs, and other harmful things.Only pathogens that are able to get through all three lines of defense can harm the body.The immune system has 3 lines of defense.

# data[].attributes.body
The body's 1st line of defense consists of different types of barriers that keep most pathogens out of the body.
pathogens are disease causing agents, such as bacteria, fungi, protozoa and viruses. Regardless of the type of pathogen the first line of defense is always the same. The skin is the most import physical barrier of the defense that the body has. The outer layer of skin is very difficult for pathogens to penetrate. Mucous membranes provide another barrier at body openings. They also line the respiratory, GI, urinary, and reproductive tracts. Mucous membranes secrete mucus, a slimy substance that traps pathogens. The membranes also have hair-like cilia. The cilia sweep mucus and pathogens toward body openings where they can be removed from the body.

# data[].attributes.body
Chemical barriers destroy pathogens on the outer body surface, at body openings, and on inner body linings. Sweat, mucus, tears, and saliva all contain enzymes that kill pathogens. Urine is too acidic for many pathogens, and semen contains zinc, which pathogens cannot tolerate. stomach acid also kills pathogens that enter the GI tract in food or water. Biological barriers are living organisms that help protect the body. Millions of harmless bacteria live on the human skin. Many more live in the GI tract. The harmless bacteria use up food and space so harmful bacteria cannot grow.

# data[].attributes.body
If you have a cut on your hand, the break in the skin provides a way for pathogens to enter your body. Bacteria would then encounter the body’s second line of defense. You may then get a cut on your hand that becomes red, warm, and swollen. These are signs of an inflammatory response. This is the first reaction of the body to tissue damage or infection. Chemicals called cytokines and histamines, which are released when tissue is injured or infected. Histamines enlarge the blood vessels and make them “leaky”. This allows white blood cells to get to the infection faster.

# data[].attributes.headline
Third Line Of Defense: What is the Immune System?

# data[].attributes.subject
Third Line Of Defense: What is the Immune System?

# data[].attributes.body
The immune system is the body system that fights to protect the body. It has a special response for each type of bacteria.

# data[].attributes.body
B cells fight infections with antibodies. Helper T cells activate the B cells and Killer T cells destroy infected and damaged body cells.

# data[].attributes.body
Memory cells allow the immune system to remember the bacteria after the infection is over. If the bacteria invades the body again, the memory cells will start dividing in order to fight it. They will quickly produce a new army of B or T cells to fight the bacteria. They will begin a faster, stronger attack than the first time the bacteria invaded the body. As a result, the immune system will be able to destroy the bacteria before it can cause an infection.

# data[].attributes.body
immune response to a pathogen produces memory cells.  the pathogen will be unable to cause a serious infection in the body if the pathogen produces memory cells. Some memory cells last for a lifetime and allow permanent immunity.

Immunization is the deliberate exposure of a person to a pathogen in order to be immune response and the formation of memory cells specific to that pathogen. only part of a pathogen, a weakened form of the pathogen, or a dead pathogen is used. This causes an immune response without making the immunized person sick. .

# data[].attributes.body
antibodies are given to a person who has never been exposed to the pathogen.  Passive immunity lasts as long as the antibodies survive in bodily fluids.
Passive immunity is aquired by a fetus through their mother’s blood. It may also be acquired by an infant though the mother’s breast milk. Older children and adults can get passive immunity through the injection of antibodies.