Try to imagine our body as a nation... a nation with long borders, with policemen and soldiers everywhere, checkpoints and barracks, with the aim of maintaining public order and keeping en-emies, who are perpetually waiting to ambush us, away.

The water in the large number of rivers and canals (our blood vessels) are monitored day and night by a powerful security system. However, it isn't easy to maintain order in a country that has billions of inhabitants, and just as many enemies and illegal immigrants.

Communication is made through a network of thin electrical cables, or through briefcases (hormones and many other types of molecules), which are released into the water. Each briefcase has a series of codes reserved only for the recipient, which it is able to recognise and pick up the minute their paths “cross”.

The briefcases may contain alarm signals sent by the squads patrolling the various districts of the body that need reinforcements. Officers from the Enemy-Eater department (monocytes) are, usu-ally, among the first to rush to their aid. Thanks to the instructions contained in the briefcases, they immediately identify the place where the alarm has gone off and reach the area by making an opening in the walls.

When they come face-to-face with the enemies, they change, becoming more aggressive and pow-erful. And so they become Big-Mouth officers (macrophages). Like in a science-fiction movie, long arms sprout from their bodies, wrapping around the enemies and quickly capturing them, after their passports have been checked.

The enemies are, literally, swallowed and enclosed in a capsule, inside the officer's body, which becomes a kind of “death chamber”. At this point they are killed, through corrosive and digestive juices, which dissolve them.