1. What is the function of the
immune system?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
The immune system performs
defense against agents, the ,
that are foreign or to the body.

Exogenous are often in contact
the skin or entering airway, the
digestive tube the genital orifices
and . They can also penetrate
circulation directly through wounds.