Which part of alimentary canal receives bile from the liver?

Bile mainly consists of: 

1. Cholesterol 
2. Bile salts
3. Bile acids
4. Bilirubin (a pigment formed after the breakdown of red blood cells)
5. Salts like sodium and potassium ions
6. Water

There are three main functions of bile in the body: 

1. Digestion of fats: After consuming a fatty meal, your hormones will send a signal to the gallbladder to release bile. Bile breaks down fats into fatty acids during a process called emulsification. The larger fat globules are broken down into smaller fat droplets, making it easier for lipase enzymes to act on them. The small intestine then takes up the emulsified fat. 
2. Absorption of Fat-soluble Vitamins: Two types of vitamins exist – fat-soluble and fat insoluble. Fat insoluble vitamins are readily absorbed from your intestines, whereas fat-soluble vitamins need bile salts to be taken up by your gut. Fat-soluble vitamins include vitamins A, D, E, and K. 
3. Excretion of waste products from the body: Bile also helps eliminate toxins from the body through faeces. Bile is essential for the removal of bilirubin, excess cholesterol, xenobiotics, and trace metals like copper, arsenic, selenium, and zinc. Failure to remove toxins can result in their build-up.

The bile is stored in a pear-shaped, sac-like organ called the gallbladder. It sits directly under the liver in the upper right area of your abdomen. The gallbladder's primary function is to concentrate and store the bile for future use.

1. The liver weighs around 1.5 kgs, making it the heaviest organ in the body. It is situated in the upper right area of the abdomen, right below the rib cage and lungs. The liver, along with bile ducts and the gallbladder together, constitutes the biliary apparatus.
2. The liver is made up of hexagonal cells called hepatocytes. These cells are placed such that they have small ductules (tubes) around them through which the bile is collected. 
3. These small ducts join together and form two bigger ducts – The right and left Hepatic ducts. These two Hepatic ducts combine to form the Common Hepatic Duct.
4. The Common Hepatic Duct then unites with the Cystic Duct, which originates from the gallbladder, to finally form the Common Bile Duct. 
5. The Common Bile Duct ultimately leads to the duodenum (part of the small intestine), where it joins with the pancreatic duct, also known as the Ampulla of Vater and opens at the duodenum through the sphincter of Oddi. This sphincter regulates the flow of bile from the ducts into the duodenum.

The liver is made up of cells called hepatocytes, and it is these cells that make the bile. The gallbladder cells are responsible for concentrating this bile and releasing it in the alimentary canal.

The hepatocytes produce bile by secreting conjugated bilirubin, cholesterol, bile salts, phospholipids, proteins, ions, and water into the canaliculi. (6) The canaliculi are small ductules which eventually join together to form the bile ducts. 

Initially, conjugated bilirubin and bile salts are secreted into the canaliculi using energy. Because of this, an osmotic and electrochemical gradient develops inside the canaliculi. This gradient leads to the flow of water and ions into the canaliculi, resulting in bile formation.

Types of Bile Salts

1. Primary Bile Salts: All bile salts are essentially Primary Bile Salts. These salts are bile acids that are derived from cholesterol and are bound to sodium or potassium. Some of these bile salts travel unaltered to the alimentary canal and thus remain as primary bile salts. 
2. Secondary Bile Salts: Secondary Bile salts are created from modifying primary bile salts. This is done by the bacteria that are present inside the gut. 

Now that you know how bile is produced keep reading to find out how it's transported from the liver to the alimentary canal!

After being synthesised in the liver, the bile is transported across the biliary system through a series of steps:

1. Step 1: The bile produced by the hepatocytes is collected via the small ductules widely distributed across the liver. 
2. Step 2: Through these ductules, it enters the right and left hepatic ducts and then the Common Hepatic Duct.
3. Step 3: From the Common Hepatic duct, the bile has two routes. It'll either go and get stored in the gallbladder for future use or traverse through the Common Bile duct and get released in the alimentary canal. Which route the bile takes depends upon the intake of fatty food.
   1. Step 3a: During Rest: When there is no food intake, the bile will travel from the Common Hepatic duct into the cystic duct and get stored in the gallbladder.
   2. Step 3b: During Digestion: When there's fatty food in the intestine, the bile enters the Common Bile duct from both the Common Hepatic and Cystic ducts to get released into the duodenum.

Bile plays a crucial role in the digestion and breakdown of fatty acids. Without bile, fats won't be absorbed in the duodenum and may result in complications when reaching the large intestine. 

Bile gives stools its yellowish-brown colour. This happens due to the conversion of conjugated bilirubin, a component of bile, into stercobilin which is a brown pigment found in stools. If there's not enough bile or some obstruction in the pathway, as seen in gallstones, you will notice clay-coloured stools. 

If bile is not released into the duodenum, you may notice the following symptoms: 

1. Diarrhoea
2. Foul smelling gas
3. Abdominal pain
4. Pale coloured stools
5. Abnormal bowel movement
6. Weight loss

Cholelithiasis

Cholelithiasis or gallstones is a common condition that refers to the presence of gallstones in the gallbladder. (9) Gallstones are bile-concentrated, pebble-like particles. They are typically composed of cholesterol or bilirubin that accumulate at the base of your gallbladder and harden into "stones."

The size of a gallstone can range from a grain of sand to a size of a golf ball.

Signs and Symptoms of Cholelithiasis:

1. Sudden, sharp pain in the upper right area of the abdomen
2. Sudden, sharp pain in the middle area of the upper abdomen
3. Back pain between your shoulder blades
4. Right shoulder pain
5. Jaundice 
6. Nausea
7. Vomiting 
8. High fever with chills

Choledocholithiasis 

The gallstones can also get lodged in the neck of the gallbladder or somewhere in the ducts, causing complete obstruction to the bile flow. This condition is known as Choledocholithiasis. 

Signs and Symptoms of Choledocholithiasis:

1. Severe pain in the central area of the upper abdomen 
2. Chills
3. Fever
4. Pale or clay-coloured stools
5. Jaundice
6. Nausea, vomiting 

Biliary Dyskinesia 

This condition may also cause a decrease in bile release. It occurs when the gallbladder functions below normal, probably due to inflammation. Symptoms of Biliary Dyskinesia are triggered after eating a fatty meal. 

Symptoms of Biliary Dyskinesia:

1. Upper Abdominal Pain
2. Bloating
3. Nausea
4. Indigestion 

The bile is formed by the liver and stored in the gallbladder. It traverses through the complex network of bile ducts and is released into the second part of the duodenum through the sphincter of Oddi. If you encounter any of the signs and symptoms of a bile salt deficiency, you must visit your doctor right away!