How does the immune system protect your body?

Answer 1

Short Answer:

The immune system senses foreign cells in the body and destroys them.

Long Answer:

Destroying, say, the common cold, begins when an antibody marks one common cold cell. It does this by attaching to the membrane. Another immune system cell, the nature killer cell (yes, THAT is its professional name), will kill this cell, but basically take pieces of that cell and add it to its membrane (kind of how in a video game you take the sword of the villain you just defeated as a trophy)

The natural killer cell will then wander over to another immune cell, known as the helper T-cell.

The helper T-cell

sees the pieces of the foreign cell and freaks out (this process is call antigen recognition). The T-cell

is now considered "activated" and begins to replicate and differentiate itself.

As all this is happening, and T-cell

that runs into a B-cell

(another immune cell) activates it. The B-cell

also begins to replicate and differentiate itself. One of the B-cell

types created then release antibodies that will bind to the foreign invader (the common cold, in this case) to mark it as an enemy.

The antibodies

go out and mark the invader, and natural killer cells, and cytotoxic T-cells

will go and destroy the infection and start the process over again until the invader has been eliminated.

This is still a brief summary of what occurs in a immune system response, but I hope it helps.

Answer 2

the immune system uses white blood cells to find and attack dangerous bacteria, viruses, etc. from spreading and creating hazardous health problems to your body.