The Incredible, Ventable Spleen

It’s out of fashion now, but there was a time when if you told someone they needed to “vent their spleen,” anyone within earshot would know what you meant. If a person was grumpy because of bottled-up sadness or anger, they were “splenetic,” a term dating to the Middle Ages, when it was assumed the spleen regulated humours, including black bile, which was thought to control mood. Rant it out, vent your spleen—same deal.

It wasn’t until the mid-twentieth century that the spleen’s functions as blood filter, blood cell factory, and red blood cell warehouse were remotely understood. A strange and wonderful organ, the spleen can grow whole new copies of itself if damaged, sending out little spleenlet cells that can latch onto other blood-rich parts of the body to regenerate; nearly one in five people have more than one spleen, most without suspecting a thing.