At the core of the system is a nanocomputer attached somewhere in the body, possibly to the back of the breastbone. Microscopic at a human scale, it is none the less huge by nano standards. This central computer controls the on-body devices through a network of sub-computers scattered throughout the body. These sub-computers in turn control billions of individual nanobots within us.

Our on-body health care system includes many highly specialized nanobots. They can be roughly classified as follows:

+ Inspector-bots – each of these is responsible for keeping track of a group of cells. It is programmed with the information it needs to inspect each cell in it’s assigned group. The inspector reports the status of each cell to one of the network computers. If anything is out of the ordinary, or if the inspector fails to report, the network computer searches it’s data banks for the correct response. If the response is found, it dispatches other robots to solve the problem. If the network computer does not have a correct response stored, it will ask for help from the central on-body computer. This computer can in turn ask for help from computers outside the body if needed. Those computers may be located in our homes, in our doctors office, or anywhere in the world.

+ Hunter-Killer bots – these are patterned after our natural white blood cells. If the threat detected is bacterial or viral, these warrior cells can find and destroy the specific threat while causing no harm to healthy systems. The ones that are commonly needed, such as those programmed to attack bacteria entering through wounds, are garrisoned at various locations in the body for rapid deployment. Less frequently called for models, such as those to fight off diseases, can be manufactured as needed with the necessary programming already in place.

+ Cell-Specialists – these are a specialized version of the Hunter-Killer bots. They are called when an inspector finds a cell which does not belong where it is. It may be cancerous, the beginning of a tumor or whatever. Since the suspect cells were produced by our own bodies they require extra care. The cell killers are programmed to perform a more detailed inspection of the offending cell and consult with the central computer before they take action. If the cell is a valid but misplaced one, they will correct it’s position. If the cell can be repaired they will do so. As a last resort, they will kill and remove the offending cell.

+ Cell-Builder bots – These provide us with capabilities we don’t naturally have. They are able to repair injuries without scaring. They allow us to grow new body parts when ours are damaged beyond normal healing (severed limbs). Some of these are also able to alter our bodies. Intelligence can be enhanced. Appearance is altered without plastic surgery. These are the tools that keep us young and vigorous.

+ Cleaner-bots – This is the janitorial crew of the body. Always on duty, they are designed to remove harmful substances from our bodies. They provide our defense against pollutants, cholesterol, poisons, etc. Other groups of these perform function like the removal of dead cells and generally augment the natural functions of our bodies.

+ Construction-bots – These are able build the other nanobots described above. They also construct computers and build communications networks as needed.

I’m sure there are many other possibilities too.