Just a quick reminder of the anatomy and where things are roughly located. We're mostly going to be talking about things in the right upper quadrant of our abdomen and going across the upper portion. So liver is quite important. You guys may talk about it when you're having a night out with cocktails, but we can't live without it. For those of you who work closely with transplant hepatologists, you may hear some conversation about liver dialysis, but that's still quite rare, not analogous to kidney dialysis. It's not at least at this juncture in time. It's not ready to prolong someone's life on the order that kidney dialysis can. Three to four pounds is about accurate. That varies with your height, body habitus, the volume of your abdominal cavity, and the overall health of the organ. There are some disease processes that can make the liver really big and some that can make it kind of shrivel up and be small. Two distinct blood sources are the hepatic artery and portal vein. And this is just a close-up of the liver anatomy. I think the relevance of emphasizing the blood flow to the liver is that it's a little bit different than other organs in the body because of the function of the liver. Typically we all learn in our high school biology class that the arteries are the primary source, that they supply the oxygen and the nutrients and so on and so forth. It's a little bit backwards in the liver. Probably the portal vein supports probably 70% to 80% of the blood flow, and the hepatic artery is about 20% to 30%. Here is a close-up of biliary anatomy, which is in the liver, but we tend to conceptualize it sometimes as a separate portion of the liver just because there are some disease processes that are in the biliary tree itself but don't necessarily affect the liver tissue around it and vice versa, but just as many that impact both. I kind of tend to think of the biliary tree as a reverse tree, whereas the liver parenchyma is supplying the bile and things go out the little branches to the larger branches and then finally out the trunk and through the major papilla or that valve in the first part of the small intestine. And you also see the gallbladder on the end, which is the sac that kind of collects the bile as it's produced throughout the day as you're fasting. So we hear the word bile tossed around a lot, but it's essentially what makes our stool dark brown, and I don't think anybody's ever escaped not vomiting or not having food poisoning, but when you're really sick, it's also what looks yellow and greenish in the vomit. How's that to ruin your breakfast? It is released in response to a fatty meal, or CCK is cholecystokinin, it's a hormone. Bile tends to help prepare the food for digestion of fat. It also helps in our, those are our fat-soluble vitamins, D, E, A, and K. We don't need a lot of it, but bad things happen if we don't have enough of it. First portion of liver function, and this is primarily related to tissue, is the synthesis. Clotting factors, it probably produces almost every single clotting factor except for factor eight. It is an important area for storage of glucose, which is the primary fuel our body needs to survive. Other proteins, I think the main one to remember is probably albumin, if any of you works closely with hepatologists, that kind of helps impact how much fluid stays in the various compartments of our bodies, and what is an appropriate amount. When people are sick with liver disease, then that function, we'll talk about later in the day, what those kind of manifestations can look like. It also helps with management of cholesterol. In addition to storage of glucose in a form called glycogen, it is also a storage place for certain trace vitamins and minerals. Again, we don't need a lot of it. We only need a little bit, but once the store of the liver runs out for whatever reason, either we're not having enough input or the liver is damaged, there can be serious health consequences. Finally, the breakdown of toxins and medications. This is the primary reason for why the portal vein supplies so much of our blood, because you can think of the liver as almost a sort of filter. We'll move on to the pancreas. It is probably, looks like skirt steak if you look at it in a surgery, and it goes across your upper abdomen. I'd say eight inches is about average, and it's actually in the plane of our abdomen closer to our back, or the retroperitoneal space, which is roughly where our kidneys are located. I tell my patients, when it's doing its job, nobody knows what it is. Nobody cares about it, but when things start to go wrong, things really, really go wrong. Up close, I think we already touched on the basic anatomy, but we have a head, neck, body, and tail, and that little portion that curls underneath is the uncinet. You'll hear us talk about it, because it's not an easily viewed place, either with endoscopic ultrasound or imaging. You'll notice here that the bile duct and the main pancreatic duct primarily empty out of the major papilla and normal anatomy, and there is a minor pancreatic duct that opens up into a tiny valve, a little bit more proximal, a little bit closer to the head, and something called valve Santorini, which if you work with advanced endoscopists that specialize in pancreatic work, you may get to see one. The pancreas function can be roughly dichotomized into exocrine and endocrine function, exo if you think of, you know, our Latin classes, stuff that comes out, usually through the main pancreatic duct. So it produces and secretes enzymes that break down fats, carbs, proteins, mostly the takeaway point is probably breakdown of fats is probably the primary function, and it can produce a large amount of bicarbonate, basically what we find in baking soda to neutralize the stomach acid. The irrelevance of that is enzymes at the end of the day are proteins, and they need to be within a certain pH level, and that's kind of just how our body, it's an amazing machine, decides on its own to help prepare everything for the next step in digestion. Endocrine function, I think we hear that talked about more because there is a whole endocrinology subspecialty just focused on hormones in the body. It is very important in glucose balance, blood sugar, so insulin to induce the absorption and glucagon if we need more of it in our bloodstream. And finally, somatostatin, so secretin is a hormone produced in the pancreas that basically stimulates the bicarbonate process, which we mentioned earlier. After you've eaten, as your stomach empties into that first part of the small intestine or the duodenum, the enzymes that are secreted by the pancreas don't tend to work very well in acidic environments, and the pancreas releases the bicarbonate to kind of neutralize that pH after the stimulus of the secretin from the duodenum. Let me go back to our main idea. Do we have any questions so far? You were talking about the gallbladder stores bile. Sure. We don't have a gallbladder. Does your liver compensate, or does the pancreas take over? Like, what organ, like, takes over that? So this is actually, like, a nice full GI question, so that's a great question. I would say in the most general terms, it tends to roughly just drip out through the bile duct in the initial stages. So people who have their cholecystectomy or their gallbladder out in the early years, they can actually get something called bile salt diarrhea, because you may have met, we've discussed earlier in our presentation that the ileum or that last portion of the small intestine is responsible. Typically after about six months to a year, your body kind of realizes, oh, this is the way things are going to be, and the ileum kind of gets back online and says, I have to work double time or triple time or whatever to reabsorb that bile salt. So that's one of the ways the body responds. The other way is people who have had their gallbladder for a long period of time, say somebody got their gallbladder out 20 years ago, we know that the common bile duct or that last trunk before it exits into the small intestine can dilate a little bit or be a little bit bigger than someone who has a gallbladder to act as a sort of reservoir for that bile. So I think that's the two main ways that the body responds. Good question.

liver

pancreas

biliary system

digestion

hormones