So, the next 15 minutes we'll focus on the digestive organ, so that'll be the liver, gallbladder, and pancreas. You already heard about the digestive tract. So let's start with the liver. It's a vital organ serving a lot of functions in our body. It is sitting in the right upper quadrant of the abdomen. We just divide the abdomen into several quadrants, and this is kind of in the right upper side of the abdomen. It is the largest solid organ, measuring about three to four pounds. The interesting and unique thing about liver itself is the blood supply. There are two sources of blood supply going into the liver, an arterial supply as well as a venous supply, both going into the liver. So usually we think veins are taking blood away. This one is actually veins taking blood into the liver, hepatic artery and portal vein. So this picture is very busy, has a lot of these almost like branches of a tree inside the liver. Some of these are blood vessels, and some of these are bile ducts. So we'll try to go through these. So the blue one here is the portal vein branch going into here. That's a big portal vein. It's actually taking blood into the liver, even though it's a vein. Same thing with the artery here. So that's the hepatic artery branch. So that's the main hepatic artery. It's taking blood into the liver. And the blood from the liver is coming out through these veins, which are the hepatic veins going into the inferior vena cava. In short, it's called IVC, and that takes it back to the heart. Liver acts as a bridge between two types of circulation in our body, a portal circulation and systemic circulation. Portal circulation is a circulation around the intestines and the digestive system, which is where the portal vein is getting that blood into. The liver is sort of detoxifying, however you want to visualize that, and then takes the blood back into the heart. So it acts as a bridge between portal circulation and systemic circulation. And we also have the biliary system, which was partly mentioned to you in a couple of slides before, a couple of presentations before, that also comes down into your small intestine, the duodenum. And I think the next slide has a little more information on that. So this is sort of the whole tree branches. So you have the main trunk of the tree and all these branches inside. So these are intrahepatic ducts, the right side, the left side. And this anatomy could be a little bit different in each individual. There could be a right-sided duct coming from the left side. There could be some variations of normal anatomy. But in the end, there are all these hepatic duct branches, which go down to the main duct, then connects to the gallbladder through this thing called the cystic duct, and then eventually comes down into the intestines through this main opening called the ampulla in the duodenum. Also the same opening, the pancreatic duct, also comes into that, and we'll review that in a couple of slides from now as well. So the function of these bile ducts is essentially to carry bile that is produced by the liver. It's a greenish-yellow fluid. Sometimes if you have seen somebody throw up, there is that greenish tinge or a yellowish tinge to the vomit sometimes, and that's the bile. The bile is stored in the gallbladder. And whenever you eat a meal, the stomach gets distended. It releases this hormone called the cholecystokinin, in short, CCK. And that causes the gallbladder to contract, and there's a sphincter muscle right at the ampulla called the sphincter of OD that relaxes. So gallbladder contraction and the sphincter relaxation, allowing the bile to come into the intestines. And the bile is useful for absorption of fat, as well as the vitamins that are dissolved in fat, vitamin A, D, E, and K. The liver has many functions beyond the production of biles. It also makes certain clotting factors, allowing the blood to clot. Glucose production, proteins, several proteins, as well as cholesterol. And the cholesterol part of it also leads to stone formation, which we'll talk again in the disease part. It also stores essential nutrients, like glucose, some vitamins. Just like in card liver, rich in vitamin A and D, similar thing. The liver is here also storing in vitamins A and D, B12 and K. It also stores iron and copper. And sometimes excessive storage of these things can result in pathological conditions, disease states like hemochromatosis, Wilson's disease, et cetera. The liver also is very useful, and this is a very important function that is relevant for us medically, because it does break down a lot of things that you ingest, not just food, medications, drugs, and toxins, as well as alcohol. Moving to pancreas, the pancreas is actually, Dr. Mathura mentioned that the duodenum is retroperitoneal. It's sitting behind the peritoneum, majority of it at least. So that makes the pancreas and the duodenum really close to the spine, even though we're kind of saying it in the front, it's actually very close to your back. So any pathology of the pancreas or the duodenum tends to have a lot of pain, not just in the front, but also going into the back. So people complain of back pain with these things. So pancreas is very close to the spine, and it's going from the right upper quadrant, again, the quadrants of the abdomen, into the left upper quadrant. It has several parts of the pancreas. You have the head that is closer to the intestines, and the tail portion that is closer to your left side where your spleen is. There's also a part of the pancreas which is called an uncinnate pancreas. Similar to the bile ducts that are draining bile juices produced by the liver into the intestines, the pancreas produces pancreatic juices. That is carried by this duct, pancreatic duct, that drains all the way into the intestine, again, the same place called the ampulla. Now interestingly, in pancreas, there is also another branch which goes to a smaller opening in the intestine called the minor papilla. This is of importance here for both the minor and the major papilla is when you talk about doing ERCP procedures, we are doing for the major papilla or the minor papilla depending on the indication sometimes. So pancreatic function is divided into exocrine and endocrine function. Exocrine is where it is producing the juices that is released into the pancreatic duct which is getting carried into the intestines. The endocrine function is where the whatever the hormones and et cetera that the endocrine aspect of the pancreas does, it is not being produced into the ducts but instead is getting released directly into bloodstream. So the exocrine function includes production of enzymes which break down your major components of your food, fats, proteins, and carbohydrates. So pancreas does play a significant role in digestion of food. It also produces bicarbonate and this is where the mixing of the acid with the bicarbonate happens to neutralize the acid that is produced by the stomach. The endocrine function produces these hormones which include insulin, glucagon, and somatostatin are the three major ones. The insulin and glucagon help in regulation of glucose metabolism. So insulin reduces the glucose, glucagon increases the glucose, and that kind of maintains a good balance between the two. So when you have certain disorders of the pancreas, sometimes people get diabetes as an effect of that. So one aspect of the homeostasis or the feedback loops that we have in our body to kind of the checks and balances that our body keeps is exemplified in this particular diagram. So this is a hormone that is actually produced by the duodenum called secretin. So the acid from the stomach enters the duodenum. The duodenum is releasing this hormone secretin into blood. The secretin is going through the bloodstream coming back to the pancreas and it stimulates the pancreas. The pancreas now is producing the bicarbonate. The bicarbonate gets released into the duodenum neutralizing the acid. So there's some sort of a feedback loop that we have in our body trying to produce as well as neutralize certain things to help digestion of food. So in summary, we talked about GI tract and health. Its function is mainly to break down and absorb food and nutrients, also for absorption of water and minerals. We talked about peristalsis, that is movement of food across the intestinal tract. And there's also storage of waste until we eliminate through the rectum. Okay. Questions? Push the thing so we can record again. The minor papilla, you can only access the pancreas through there. So the bile ducts can't be accessed through there. It's just the pancreatic. Correct. Okay. So there are certain disease states like pancreas divism, for instance, where the main pancreatic duct instead of going into the major papilla is draining to the minor papilla. So it becomes more essential in those cases. If you try to access the pancreatic duct from the major papilla, you cannot access it. So you actually have to go through the minor papilla to access the pancreatic duct in those cases. So when you're doing any intervention on minor papilla, it's mainly for the pancreatic intervention. Okay. All right. Do you mind just repeating again the systemic circulation and what that does? So systemic circulation is the rest of your body. Like, you know, the typical thing that we think about where, you know, blood is going out of the heart into your different parts of the body and it's taken back to the heart. That's systemic circulation. Okay. And that circulation surrounds around the intestines. So the blood is taken from the intestines, the digestive organs, digestive tract, and then it's taken to the liver, and that's when the portal and the systemic sort of bridge.

digestive organs

liver

gallbladder

pancreas

anatomy and functions