Source: Video and Images Created by Amanda Soderlind
Welcome to this lesson on accessory organs.
Today we are going to be taking a look at the pancreas, gallbladder and liver, and investigate their role in digestion.
The pancreas, gall bladder and liver are identified as accessory organs. What this means is that they play a role in digestion, but they're separate from the digestive tract. So let's take a look at each of these individually and identify their role in digestion.
The pancreas is the first accessory organs we're going to take a look at. And if we label that on our diagram down here, it is the part in orange. The pancreas is an organ that releases enzymes which help to break down carbohydrates, lipids, proteins, and nucleic acids in the body. And it also plays a role in regulating our blood sugar levels. So a person who has Type 1 or Type 2 diabetes has issues with their pancreas, where they're not able to produce insulin, which helps to regulate blood sugar levels. So it releases these enzymes that help break down these materials in indigestion. And these pancreatic juices also help to neutralize the acids in chyme. Chyme is a very acidic substance, but the pancreatic juices contain substances that help to neutralize those acids as it moves through the digestive tract.
The liver is our next organ that we're going to talk about. The liver produces bile. Bile is the substance that aids in the digestion and absorption of fats. So our liver is located here in red.
In addition to producing bile for digestion, the liver actually has many different roles in the body. Some of them are digestive-related, and some of them aren't. These are just a few of the additional functions. The liver actually has many more functions besides just this. But just to give you an idea of some other functions of the liver. It stores vitamins and minerals, its stores glucose as glycogen, and it helps remove toxins such as alcohol from the blood.
It's related to the hepatic portal system. This hepatic portal system is a system of blood vessels that diverts blood from the small intestine to the liver. So basically what happens is nutrient-rich blood is delivered from the small intestine, through the hepatic portal system, back up to the liver. From there, nutrients that are in that blood from digestion are either processed or stored, or they can be used for synthesis of proteins, or used by cells to make ATP. The liver will determine what needs to happen with these substances. If there, for example, is too much glucose in that blood that's delivered to the liver, it will store some of that glucose, as I mentioned, as glycogen. If there's a certain vitamin or mineral that happens to be really high in the blood at that time, it can also store some of those extra vitamins and minerals, such as iron, for example, in the liver until it's needed later, as well.
The gallbladder is the third accessory organ we're going to discuss today. The gallbladder basically stores bile, and releases the bile into the small intestine when it's needed. Our gallbladder is this green bulb here on our diagram. As I mentioned, bile is produced in the liver, but it's actually stored in the gallbladder. So when bile is needed-- if there are fats that need to be digested or absorbed-- the gallbladder will release some of this bile through the bile duct. This green duct here would be the bile duct, and then into the small intestine here. So its stores and releases bile when necessary.
This lesson has been an overview on the structure and function of the pancreas, gallbladder and liver.
A secretion created by the liver that is used to aid in the digestion of lipids (fats).
The organ that stores bile until we need to secrete it; bile is transported from the gallbladder into the duodenum through bile ducts.
A system of veins that drain blood from the stomach and intestines to the liver; a portal system consists of two consecutive capillary beds connected by a portal vein(s).
The largest of the visceral organs, the liver produces bile and secretes it into the gallbladder to be stored. The liver also processes nutrients such as amino acids and carbohydrates and also “detoxifies” the blood.
A mixed organ (both endocrine and exocrine) that produces and secretes pancreatic juices into the small intestine that aid in the digestion of food.