The Body’s Defenses Explain how the body’s first line of defense guards against pathogens Describe what happens during the inflammatory response State how the immune system responds to pathogens

The Body’s Defenses Our bodies have an army of soldiers for protection from invaders All of them work together, forming the immune system

Barriers In the first line of defense, the surfaces of the skin, breathing passages, mouth, and stomach function as barriers to pathogens These barriers trap and kill most pathogens with which you come into contact

Barriers Skin Pathogens land on skin and are exposed to destructive chemicals (oil and sweat) Pathogens may also fall off with dead skin cells Then they must get through tightly packed dead cells that form a barrier over live cells Most enter through cuts in the skin

Barriers Breathing passages Nose, pharynx, trachea, and bronchi contain mucus and cilia The mucus and cilia trap and remove most of the pathogens that enter Pathogens may irritate as they enter making you sneeze or cough kicking the pathogens out

Barriers Mouth and Stomach Some pathogens are in foods The saliva in the mouth contains chemical may kill The stomach produces acid which can kill pathogens

The Inflammatory Response When body cells are damaged, they release chemicals that trigger the inflammatory response This is our 2nd line of defense

The Inflammatory Response In the inflammatory response, fluid and white blood cells leak from blood vessels into nearby tissues The white blood cells then fight the pathogens

The Inflammatory Response White blood cells All are disease fighters Phagocytes- type of WBCs that are involved in the inflammatory response Engulfs pathogens and destroys them

The Inflammatory Response Inflammation Blood vessels widen in the area affected by the pathogens. This enlargement increases blood flow to the area causing more disease fighters to go to the scene The enlarged blood vessels makes the area red and swollen. If you touch the swollen area, it will fell warmer than usual

The Inflammatory Response Fever Chemicals in the response cause a fever It helps our body fight infection Some pathogens do not grow and reproduce well at higher temperatures

The Immune System Immune response- if pathogen infection causes fever, it triggers the 3rd line of defense – immune response The cells of the immune system can distinguish between different kinds of pathogens. The immune system cells react to each kind of pathogen with a defense targeted specifically at that pathogen

The Immune System Lymphocytes White blood cells that distinguish between different kinds of pathogens Two major types B cells T cells

The Immune System Lymphocytes T cell- functions to identify pathogens and distinguish one kind of pathogen from another We have 10’s of millions of T cells T cells recognize antigens (molecules that the immune system recognizes as foreign)

The Immune System Lymphocytes B cells Produce proteins that help destroy pathogens These proteins are antibodies Each kind of B cell produces only one kind of antibody, and each antibody has a different structure

The Immune System Lymphocytes B cells Antigens and antibodies fit together like puzzles Antibodies bind to antigens so that they will be recognized and destoryed

The Immune System AIDS- disease caused by a virus that attacks the immune system Virus= HIV

The Immune System AIDS HIV is the only kind of virus known to attack the human immune system directly and destroy T cells HIV destroys T cells and the body loses its ability to fight disease

The Immune System AIDS- how it’s spread It can only reproduce in cells HIV can spread from one person to another only if body fluids from an infected person come in contact with those of an uninfected person Sexual contact, Pregnancy, Infected blood

Assignment: IS Analogy Your body is its own nation. You have recently been invaded. Explain your war strategy against the enemy. You will have three battles, describe your defenses for each.