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Our Bodies Are Heroes!


Thudd not get sick.  Thudd get rusty!

Many things outside our bodies are dangerous.  But our bodies have lots of ways of protecting us: 


Skin keeps things from getting inside our bodies.


Tears keep eyes clean. 


Nose hairs help to clean the air that goes into lungs.  Mucus in noses traps and washes away some of the nasty little things that manage to get by.  


Coughing and sneezing helps get rid of some invaders.

Some harmful things -for example, bacteria and viruses -- will always sneak by these defenses.  But our bodies have an army of special cells.  It's called the immune (im-yoon) system.    These cells patrol our bodies and search for invaders. 

The immune system can tell the "good guys" from the "bad guys" by what they wear! 


For example, your body is made up of cells, like the dish-shaped red blood cells in this picture.  They carry oxygen to every part of your body.  The other scruffy looking cells are part of the immune system army.

The outsides of cells are marked by lumpy, bumpy molecules.  (They're too small to see here.)  Your cells are wearing your team uniform -- a lumpy, bumpy uniform! No two people on Earth have exactly the same uniform! Your special pattern of molecules tells your immune system that these cell are yours!  Don't attack!


Other things that enter your body wear different uniforms.   The immune system army checks everything that comes in.  It recognizes that some are okay and lets them pass.

When the immune system army finds an enemy, it goes into action.  The army itself multiplies very fast.  Cells work together to find the invader.  Then they attack.  They squirt the enemy with powerful chemical weapons that can heat them up and destroy them.  Then they eat them!

The big blue cell in the photo below is called a macrophage (mac-row-fage).  The word macrophage means "big eater"!

Find out what's going on!  Run your cursor over the picture!

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For example, when you get a cut, it gets a little red.  Maybe it feels hot and itchy. 

That's because the cells of your immune system have arrived on the scene.  They're squirting their chemical weapons on the invading bacteria!  These chemicals are kill bacteria.  But the chemicals are so strong, they're also making you feel a little itchy and uncomfortable. 

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