pancreas
"Glucose is like the fire within you... The Pancreas is like an Air-Conditioner...
Insulin is like Cool Air...
Beta Cells are like Light Bulbs...
Carbohydrates are fuel for the fire..." The linked page is a highly metaphorical discussion of the human body.
"We can use the analogy that the pancreas is like a building manager that uses a key (insulin) to unlock the building so that the employees (glucose) can go to work (enter the cells)."
"My pancreas is like a bad boyfriend hanging around doing nothing, stressing me out, causing me to use drugs, and being an all around pain in the ass"
"It is a testament to reliability that most adults do not know much about the pancreas. We don't simply because we don't have to. From the moment of birth, the pancreas is like a machine on autopilot - silently working in the background doing its job meal after meal, day after day. We may only have one pancreas, but it usually lasts a lifetime processing over 100,000 meals and rarely ever breaks down."
"The pancreas is like a raisin-cake, with the Islets of Langerhans represented by the raisins."
"The pancreas is like a tree, where the ducts are the branches, and the islets [of Langerhans] are like bird's nests," she says. "They don't communicate with the tree itself, but they have to have a tree to live." Those bird's nests, and the insulin-producing beta cells within them, are crucial to human health - when beta cells go awry, diabetes results."

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.