Notice how our purple invader is being swept through the intestine along with digesting food.

Peristalsis is the wave-like contraction of smooth muscle in the intestine. This process is continually occurring in our body, and keeps food moving through our intestine. The continual movement makes it difficult for invading microorganisms to stay in place long enough to start an infection.

If you were an invader, how would you avoid being swept out of the intestine?