On Monday, we had our renal system exam. After two-and-a-half weeks, we’ve finished our journey through the kidneys and their combined 2.5 million nephrons, as well as the ureters, bladder, urethra and prostate (where applicable). It was a fast-paced and fascinating journey, although I’ve barely caught my breath and we’re already on to studying the GI system.
Today we learned about the pancreas, which I’ve found to be more interesting than any other organ I’ve studied so far. Including the brain. Some people may argue that the brain is much more fascinating than the pancreas, but I really like the pancreas. (Please excuse my bias if you happen to be a passionate lover of the brain. It really is amazing also.) I guess I just never pondered how I have the ability to digest myself, and I think it’s amazing that I don’t. I mean, it sounds rather like science fiction, doesn’t it? The power of self-digestion. It’s the closest thing I have at this point to a super-power, except it’s one that wouldn’t save the world.
Let’s talk a little about the pancreas and why I’m digesting my dinner and not myself right now (unless I were to get acute pancreatitis at some point. Which I rather hope I don’t.). The pancreas produces several different digestive enzymes to break down protein, fat, and nucleic acids. This arsenal is essential for digesting the nutrients in the steak salad I ate this evening, but it’s also perfectly capable of breaking down my own cells. However, these enzymes are actually stored as inactive precursors, so they aren’t able to do any damage in the pancreas. It’s only once they’re released into the intestine that they can be activated, and by that point it’s safe to do so.
The activation cascade itself is quite beautiful. In the intestine, there is an enzyme that activates trypsinogen (an inactive precursor) into trypsin (a protein-digesting enzyme). Trypsin then cleaves all the other inactive enzyme precursors into their active forms, and suddenly your intestine has all the digestive enzymes it needs.
On top of all this, there are mechanisms inside the pancreas to stop this cascade from taking place just in case it’s accidentally triggered too early. There’s another protein hanging around that inhibits any trypsin that might have been aberrantly activated. And there are to more enzyme precursors that, if activated in the pancreas by trypsin, will actually turn around and break it down!
I’ve tried to make this easier to read by omitting most of the specific enzyme names, as words like “mesotrypsinogen” and “phospholipase A2” are a bit of a mouthful (but still much easier to say than “focal segmental glomerulosclerosis,” one of the diseases we learned about in renal block!). If you’re interested in learning about it in much more detail, though, there’s information here!
How is it possibly 1:30 AM? I guess I’d better go study about the pancreas a little more before going to bed…goodnight!
P.S. What do you think of the title of this post? It sounds like a fruit juice blend… 🙂