9781422280300

Meet the Immune System

front lines of battle. Its supply chains provide those troops with weapons and aid. It even sends elaborate, coded messages between different units and battalions. When this army is doing its job well, it destroys invaders before they have a chance to make you sick. But sometimes your army may be overwhelmed by a particularly numerous or powerful invader. When that happens, you get sick. Your immune system may rally on its own, or it may need some help. Modern medicine has developed many drugs and treatments to aid your immune system in battle. Thanks to this help, our immune systems can now defeat some of the deadliest pathogens. But the immune system can also make mistakes. It may fire on harmless particles, like pollen that you breathe in, or food that you eat. This creates allergies. Or your immune system may get confused and think your own healthy cells are the enemy. These “friendly fire” attacks cause autoimmune disorders. These mistakes can also make you sick. Some cause mild illness, but others can be very severe, even life-threatening. To understand what happens when the immune system makes mistakes, let’s first take a closer look at how the immune system works.

Educational Video Scan this code to watch an animated video about the immune system.

Barriers One of the oldest and simplest ways to defend against an attack is to build a wall to keep the enemy out. Your body has a wall: your skin. One of the most important parts of your immune system, your skin, keeps out the billions of pathogens that land on you. Your skin isn’t just a wall, though. It contains special

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