immune system
"A person's immune system is like a library that contains information about every germ ever defeated. If the person encounters the real disease-causing germ in the future, their immune system will know how to defeat it, often before the person experiences any symptoms of illness. This explains why (in most cases) you only catch diseases such as mumps and rubella (German measles) once, even though exposure to the viruses may be repeated throughout life."
"Our immune system is like a tightrope walker up on the high wire, constantly balancing, carefully navigating the fine line between under- and over-reaction to external challenges. "
"The Immune System is like an orchestra. Each musician may play beautifully on her own, but she can hardly compare to the beauty and complexity of an entire orchestra that is playing perfectly together.In a way, its functioning is similar to an orchestra too. If one violinist didn't show up, you would hardly notice. But if the entire string section were to go missing then the quality of the music would be greatly affected. "
"A healthy immune system is like a carefully balanced teeter totter. Tip it one way, and your immune system weakens, leaving you vulnerable to pathogens. Tip it the other way, and your immune system becomes overactive and attacks your own healthy tissue. Such overactive immune systems cause what we call autoimmune diseases, like lupus, Crohn's Disease, rheumatoid arthritis, and psoriasis. These are not things you want. If boosting your immune did have some actual medical meaning, it would be the last thing any healthy person should want to do "
"The immune system could be described as a sensory organ much like vision, hearing and touch. Instead of recognising light, sound waves or large objects, the immune system recognises molecular shapes - only a few amino acids in length. Those shapes lacking a self identification tag may be recognised as foreign, triggering a series of events that eventuate in an immune response. This module discusses the various ways in which the body protects itself against infection and how vaccination works with these processes. The description that follows is simplified; however there are many excellent immunology textbooks and websites are available to provide additional detail and are recommended at the end of this module. Keep in mind that the immune system is like an octopus - therefore difficult to cover in a linear page-by-page fashion."
The link is a nice, clearly written summary of the human immune system.
This is the most common association for the immune system. There are many other phrases that fall into this category; they are army, security guard, mote or maybe cellular submarine force. A more apt association would be the naval association. If face, we are pretty much mostly water, a defensive submarine force is a good visualization.
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.