Med-Surg - Gastrointestinal System, part 2: Pancreas, Liver, Gallbladder, Biliary Tract - Anatomy and Physiology Review
by Cathy Parkes November 20, 2021 Updated: December 07, 2022 4 min read
Hi. I'm Cathy with Level Up RN. In this video, I am going to continue my anatomy and physiology review of the gastrointestinal system. Specifically, I will be talking about accessory organs of the GI system, which include the pancreas, liver, and gallbladder. Throughout this video, I will be following along with our Level Up RN medical-surgical nursing flashcards. So if you have those, definitely pull those out so you can follow along with me. At the end of the video, I'm going to give you guys a little quiz to test your knowledge of some of the key points I'll be covering in this video. So definitely stay tuned for that.
Let's first talk about the pancreas, which has both exocrine and endocrine functions.
As an exocrine organ, the acinar cells in the pancreas will secrete inactivated enzymes that travel to the small intestine where they become activated, and then they help to digest carbohydrates, fats, and protein. Now, later on in this playlist, we're going to talk about pancreatitis, which is a disorder that causes premature activation of those enzymes before they reach the small intestine and that causes auto digestion of the pancreas.
As an endocrine organ, the islets of Langerhans are cells that produce hormones that regulate blood sugar levels in the body.
So examples of hormones include insulin and glucagon. So if you want more details about the endocrine function of the pancreas, definitely go and check out my endocrine system playlist. So I go in a lot of detail in that playlist about insulin and diabetes, etc.
Next, we have the liver, which is comprised of two lobes, and each lobe is made up of lobules, which are the functional units of the liver.
The liver is responsible for many things in the body. This includes the storage of minerals and fat-soluble vitamins, bile production and secretion, bilirubin metabolism and secretion, detoxification of harmful drugs and substances. It's also responsible for plasma protein synthesis. For example, albumin and clotting factors.
So albumin is an important protein that keeps fluid in the bloodstream, and clotting factors are needed for clotting or hemostasis.
The liver also plays a role with fat metabolism, including cholesterol synthesis and elimination. It plays a role in carbohydrate metabolism as well. For example, glycogenolysis is the breakdown of glycogen, which is stored carbohydrate energy in the liver, and it breaks down that glycogen to glucose as needed. So you can see that there are a lot of different functions of the liver.
So when we talk about disorders of the liver, such as cirrhosis, we're going to see a laundry list of signs and symptoms associated with those disorders because of all of these functions.
Next, we have the gall bladder, which is a pear-shaped organ that is located underneath the liver.
So the gallbladder stores and concentrates bile from the liver. So the liver makes the bile. The gallbladder stores that bile, and then it releases bile into the small intestine where it emulsifies fat.
Let's take a look at the biliary tract. Here's an illustration from our medical-surgical nursing flashcard deck. So when I was in nursing school, I longed for a simplified illustration like this to better understand the different ducts and the flow of bile, and I never did find it. So I hope this illustration is helpful for you along with my explanation.
So here we have the gallbladder, and that resides underneath the liver, which is not shown, but we do show the left and right hepatic ducts, which would be coming off the liver.
So the left and right hepatic ducts combine to form the common hepatic duct.
And so off of the gallbladder, we have the cystic duct, which combines with this common hepatic duct to form the common bile duct.
And then the common bile duct combines with the pancreatic duct, and then it empties into the small intestine here at the sphincter of Oddi, which is in the duodenum. So bile will leave here, go through the cystic duct, come down here, go through the common bile duct and then into the small intestine.
So later on in this video playlist, we're going to talk about cholecystitis, which is the inflammation of the gallbladder, and that is typically caused by cholelithiasis, which is a gallstone.
So depending on where that gallstone is will determine what kinds of signs and symptoms your patient will have. So often you will find that gallstone in the cystic duct, which will cause inflammation of the gallbladder and symptoms that are specific to the gallbladder. However, if that gallstone resides in the common bile duct, then we can end up with bile backing into the liver, which will cause liver symptoms as well as gallbladder symptoms. And we can even have a gallstone that causes issues with this pancreatic duct, which in turn can cause pancreatitis.
So I just find it helpful to look at all these ducts and think about: if a gallstone was here, what would happen, and if a gallstone was down here, what would happen, and if it was here, what would happen? It just makes sense when you see these different branches and know where each of them go.
All right. It's quiz time. I have three questions for you. First question. Which GI organ has both exocrine and endocrine functions? The answer is the pancreas.
Question number two. Which GI organ stores and concentrates bile from the liver. The answer is the gallbladder.
Question number three. Which GI organ is responsible for the synthesis of albumin? That would be the liver.
Okay. That concludes our anatomy and physiology review of the gastrointestinal system. In my next video, I will be covering diagnostic tests, and then we will get into disorders. So definitely stay tuned for that.
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