Welcome. You might just have taken a bite of a sandwich or sipped some coffee. That gives a nice satisfying feeling. But after you swallowed, the work has just begun for your body. Your food or drink will be taken through a labyrinth of organs. Probably you'll already have an idea which, but I am here to take you through them in detail. You will learn where the organs lie and what their functions are. This will help you to visualize what's under the skin if you look at the person's abdomen. Also, you'll learn the official names of the organs. You will need those in nearly anything you study or read about abdomen. Okay, let's start. You just swallowed a bite of bread, it passes through the esophagus, not much exciting happens digestion-wise in the esophagus. The main function of the esophagus is to bridge distance between your mouth and abdomen. So can we then simply view it as a garbage chute? No. Because you also can swallow if you're upside down. The food is actively transported by muscles in the wall of the esophagus that contract and push the food forward. Now the food arrives in the stomach. Gaster is the Latin name for stomach. We will encounter that term later on in names of things related to the stomach. The stomach has a few functions. First of all it's a mixer. Several chemical fluids are added to the food and then the whole is mixed until it becomes a semi-fluid mixture called chyme. The chemicals help in the digestion. Also one of these fluids is a very strong acid that kills bacteria. Here you can see the movements of the stomach in reality on an x-ray video. This is a dog stomach, the stomach is filled with compressed substance. You can see that the contraction in the last part of the stomach, the antrum, moves forward, thereby squeezing a bit of the chyme onward to the duodenum. Another part of the chyme is squeezed backward into the stomach, mixing it effectively. The stomach is also a waiting room. You can eat a whole meal in a short time, but you cannot digest it as quickly. So the food has to wait in the stomach for it to be released to the intestines bit by bit. The gatekeeper that controls the passing on of the chyme bolus is at the border of the stomach and the small intestine and is named the pylorus. Here you see the human pylorus in reality. As seen from whizzing the stomach during a gastroscopy. It's a strong circular muscle in the intestinal wall where the stomach transitions to the small intestine. After having passed the pyloris, the chyme bolus enters the small intestine. The beginning and end of the small intestine have been indicated with lines here. The small intestines are the place where the main digestion of the foods takes place. What is digestion? Digestion is in fact breaking down the food into very little pieces. It's basic building blocks. You can compare it with breaking a cake of Lego into its separate Lego bricks. All food stuffs are made up of substances such as carbohydrates, proteins, and fats. And to be able to be absorbed by the intestines, these must be broken into smaller parts with names such as glucose, amino acids, and fatty acids. And the small parts are then absorbed from the intestines into the blood. They are the basic elements that in turn can be used to build the tissues of the body. Just as you can build something new from Lego blocks. And also, they can be used as energy. Lets have a look at the intestines, where this all happens. The first part of the small intestines is called the duodenum. We'll zoom in a bit. It is C-shaped, it curves around this long structure, indicated in yellow here, the pancreas. The pancreas produces chemical fluids that help in the digestion. It deposits these fluids into the duodenum, Next, drawn in green, is the bile duct. It runs from the liver to the duodenum, and to the side of the bile duct the gallbladder is attached. The liver produces bile, the bile is needed for the digestion of fats, and the bile can either run directly into the duodenum or be stored temporarily in the gallbladder. Thus, in the duodenum, the chyme bolus is mixed with many digestive chemical fluids from the stomach, from the pancreas, and from the liver. And also the intestines themselves produce digestive chemicals. All these chemicals together perform the digestion that is break the food into its little building blocks. And these pieces are then absorbed in the walls of the intestines. And here is the place where this all happens, as seen during endoscopy, a normal human duodenum. Note that the duodenum is partially hidden behind a part of the large intestine. The rest of the small intestines are not hidden but directly accessible if you would open the abdomen, and lift an apron off that, that covers it loosely. This rest is divided into two parts: the first half is named jejunum, the second half ileum. There is no sign post indicating a transition of jejunum to ileum. They just have slightly different characteristics. For instance the jejunum is somewhat wider, and it's internal wall is folder more strongly which helps the absorption, which is maximal here. And these characteristic change gradually from the jejunum to the ileum. This x-ray video gives an impression of the movements in the small intestine. When the chyme bolus has passed through the small intestine, it arrives in the large intestine. The large intestine is divided into several parts. First there's a blind pouch named caecum with the appendix connected to it. And the rest of the large intestine is named colon, with the following subsequent parts following the flow of the bowels. An ascending part, the transverse part, and the descending part and the partr named sigmoid after the Greek letter for s, Sigma, because of it's s shape. Finally, the chyme mass which has now become feces enters the rectum. The first part of the first half of the colon mainly extracts water. So the food mass becomes semi-solid and the second half is mainly a storage place where the feces waits until it can be disposed of. The colon has classic contractions and bulbs in between named haustra. And on the video of a big cecum and colon, you can see how these arise. To summarize in this video we followed the route of the food. We gave you the names of the individual intestines, and we discussed the functions of the intestines.
