Peritoneal Attachments and Ligaments

The liver is attached to surrounding structures by several ligaments. The falciform ligament attaches it to the diaphragm and anterior abdominal wall and separates the right and left lobes. The round ligament lies within the free edge of the falciform ligament and represents the obliterated umbilical vein. The coronary and triangular ligaments attach the liver to the diaphragm. The hepatogastric and hepatoduodenal ligaments connect the liver to the stomach and duodenum.

Blood Supply and Portal Circulation

The liver receives blood from two sources. The hepatic artery supplies oxygenated blood, while the portal vein carries nutrient-rich blood from the digestive tract. The portal vein also transports absorbed drugs and toxins to the liver. After processing these substances, blood leaves the liver through the hepatic veins and drains into the inferior vena cava.

Functions

The liver produces bile, which is collected by the bile ducts. Bile may either pass directly into the duodenum or be stored in the gall-bladder before release. The liver is also involved in carbohydrate and nitrogen metabolism. It stores carbohydrates in the form of glycogen and releases sugar into the bloodstream when needed. In addition, some liver cells participate in the destruction of red blood cells.

Microscopic Structure of the Liver

The liver is composed of three main microscopic components: hepatocytes, bile canaliculi, and hepatic sinusoids.

Hepatocytes are the main functional cells of the liver and make up about 80% of its volume. They are responsible for a wide range of secretory, metabolic, and endocrine functions. Within each hepatic lobule, hepatocytes are arranged in plates called hepatic laminae, which radiate outward from the portal vein.

Between adjacent hepatocytes are tiny channels known as bile canaliculi. These small passages collect the bile produced by hepatocytes. Bile then flows from the canaliculi into bile ductules, which unite to form bile ducts. The bile ducts merge into the right and left hepatic ducts, which join to form the common hepatic duct. This duct later joins the cystic duct from the gall-bladder to form the common bile duct, which carries bile to the small intestine.

Hepatic sinusoids are specialized blood-filled spaces formed by branches of the hepatic portal vein and hepatic artery. They contain nutrient-rich and oxygen-rich blood and allow close contact between the blood and hepatocytes. This arrangement enables hepatocytes to process nutrients, toxins, and waste products efficiently. Substances such as bilirubin are removed from the blood and secreted into bile, while proteins, lipids, and carbohydrates may be processed, stored, or released back into the bloodstream.

Blood from the hepatic sinusoids drains into a central vein, which ultimately empties into the hepatic veins and then the inferior vena cava. Blood and bile therefore flow in opposite directions through the liver.

The sinusoids also contain specialized phagocytic cells called Kupffer cells. These cells remove old red and white blood cells, bacteria, and other foreign material from the blood.

At the edges of hepatic lobules lies the portal triad, which consists of three structures:

• A branch of the hepatic portal vein

• A branch of the hepatic artery

• A bile duct