I'll just quickly talk about the accessory organs of digestion. We've got three accessory organs of digestion excluding the salivary glands which I've talked about in the first part on the mouth and pharynx. In this tutorial, we're going to talk about the three accessory organs of digestion in the abdomen.
The three accessory organs we've got in the abdomen are the liver, the gallbladder and the pancreas.
The liver lies in the upper right quadrant. You can see this organ here, this triangular-shaped organ, which sits underneath the diaphragm. I just added in the diaphragm here and you can see it lies over the abdominal viscera.
The function of the liver is metabolic. It receives nutrient-rich blood from the gut via a vein called the portal vein, the hepatic portal vein. Blood which comes from all the other gut structures enters the liver via portal vein. The liver then processes the products of digestion. It also produces bile.
Just sitting underneath the liver, you've got this little structure, this little sac called the gallbladder. The liver which produces bile stores and concentrates its bile in the gallbladder. It passes from the liver via various ducts into the gallbladder. You can see this little sac sitting underneath the liver. You can see these various ducts (they're kind of faded out). This forms the biliary system.
When food enters into the stomach, a hormone is released which makes the gallbladder contract and the gallbladder then releases bile. And as I mentioned in a previous part, the gallbladder has various ducts which empty into the duodenum. The bile enters into the duodenum to assist in the digestion of the chyme, which enters from the stomach.
Lying behind the stomach, we've got the pancreas. You can see this structure here. The head of the pancreas sits in the curve of the duodenum and the tail extends to this organ, the spleen.
The pancreas has endocrine and exocrine functions. The endocrine functions are producing insulin and glucagon. Its exocrine function is to produce pancreatic juice, which is secreted into the duodenum and this aids digestion.
That’s the end of my introduction to the digestive system. We've gone through the alimentary tract. We've gone through the tube from mouth to anus talking about the mouth, the pharynx, the esophagus, the stomach, the small intestine consisting of its three parts, the large intestine consisting of the various parts of the colon, the cecum and then you've got the rectum and anal canal finally ending in the anus. And then you've got these accessory organs which aid digestion. You’ve got the liver, the gallbladder and the pancreas.