Anatomy of the Liver - Structure, Location, and Functions

Introduction:

The liver is situated in the right upper region above the stomach, covered by the rib cage. It comprises about two to three percent of the body weight. It is dark brown and rubbery in texture. This organ has two blood supplies, unlike any other organ in the body. The liver has two lobes, a right lobe, and a left lobe. The functions of the liver are that it helps in digestion and the removal of toxic wastes from the body. Any dysfunction of the liver leads to liver disease and liver failure. A few factors like alcohol consumption, taking certain medications, and viral infections also cause liver disease.

What Is the Structure of the Liver?

The liver is located in the right upper region below the diaphragm (a muscle that involves respiration) and above the stomach, intestine, and right kidneys. The liver is wedge-shaped and weighs around three pounds. A thin layer of tissue called Glisson’s capsule forms the covering of the liver. The liver has four lobes, a large right lobe and a left lobe, a caudate lobe, and a quadrate lobe. The falciform ligament is a fibrous structure connecting the liver and the abdominal wall. The falciform ligament splits the liver into the right and the left lobe.

What Are the Segments of the Liver?

According to French surgeon Claude Couinaud, the liver has two lobes, two hemilivers, four sectors, and eight segments. The lobes are divided by a falciform ligament, and the two hemilivers are split by cantlie’s line. The four sectors are set apart by the portal fissures. Finally, the eight segments are differentiated by an imaginary vertical line that passes through the bifurcation (dividing part) of the portal vein.

• The Two Lobes:

  • The right lobe.

  • The left lobe.

• The Two Hemilivers:

  • The right hemiliver.

  • The left hemiliver.

• The Four Sectors:

  • The right anterior sector.

  • The right posterior sector.

  • The left lateral sector.

  • The left middle sector.

• The Eight Segments:

  • Caudate lobe - Segment I.

  • Left posterosuperior lobe -Segment II.

  • Left anterior inferior - Segment III.

  • IVa superior segment.

  • IVb inferior segment.

  • Inferior segment - Segment V.

  • Superior segment - Segment VIII.

  • Inferior segment - Segment VI.

  • Superior segment - Segment VII.

The caudate lobe, the left posterosuperior segment, the left anterior inferior segment, and the left medial segments are the segments of the left liver. The medial segments are further divided into the superior and inferior segments (IVa and IVb).

The segments of the right liver are the right anterior inferior V, the right posteroinferior VI, the right posterosuperior VII, and the right anterior inferior VIII.

What Are the Parts of the Liver?

The liver has a few important parts.

• Common Hepatic Duct: These tubular structures carry bile within the liver, which is possible by a group of tiny tube-like structures called intrahepatic bile ducts. These tiny tubules together form the left and the right hepatic duct, which in turn unites and joins to form the common hepatic duct.

• Common Bile Duct: A tube-like structure that carries bile from the liver and the gallbladder to the first part of the intestine (duodenum).

• Falciform Ligament: This ligament divides the liver into the right and the left lobe. The falciform ligament helps the liver attach to the abdominal wall.

• Glisson's Capsule: This is a layer of connective tissue that covers the liver and its structures, like ducts and blood vessels.

• Hepatic Artery: This is a vital blood vessel that supplies oxygen-rich blood to the liver.

• Hepatic Portal Vein: This blood vessel transports blood from the spleen, gallbladder, pancreas, and intestine to the liver.

• Lobes: Lobes are anatomical divisions of the liver.

• Lobules: Lobules are the constituent elements of the liver. Thousands of lobules form the lobes.

• Peritoneum: Peritoneum is a layer that covers the liver from the outside.

What Are the Functions of the Liver?

• Albumin Production: Albumin is a protein produced in the liver. It keeps the fluid in the blood intact without leaking into the surrounding structures. Albumin helps transport enzymes, hormones, and vitamins to all body parts.

• Bile Production: The liver produces a liquid called bile stored in the gallbladder. Bile is a green-colored liquid that helps remove waste from the body and helps in digestion by breaking down fats.

• Manages Blood Clotting: The blood clotting factors like prothrombin and fibrinogen are produced in the liver. Vitamin K has an essential role in the formation of clotting factors. The liver regulates blood clotting.

• Maintains Amino Acid Levels: The liver consists of many non-essential amino acids and essential amino acids. These amino acids participate in many processes like lipids synthesis, cellular level metabolisms, and removing waste products from the blood. The liver maintains the levels of amino acids in circulation.

• Blood Filtration: The liver plays a significant role in filtering blood that exits the intestine and the stomach. It removes harmful wastes and byproducts from processing food or other processes.

• Vitamin and Mineral Storage: The fat-soluble vitamins A, D, E, and K and vitamin B12 are stored in the liver.

• Fights Infections: The liver removes harmful organisms that cause various infections while filtering the blood.

• Processes Blood Sugar: The liver's primary function is to absorb sugar (glucose) from the food ingested and provide energy to the body. It stores the excess sugar in the form of glycogen and releases it later when there is energy demand.

• Clears Bilirubin: Bilirubin is a yellow-pigmented liquid that results as a byproduct of the normal breakdown of hemoglobin (a blood protein that delivers oxygen). The liver removes the bilirubin from the blood, as its accumulation will lead to jaundice (yellowish discoloration of the skin and the eyes).

What Are the Types of Liver Diseases?

• Alcoholic Fatty Liver Disease: This disease is due to fat accumulation in the liver due to excess alcohol consumption leading to liver damage.

• Non-Alcoholic Fatty Liver Disease: The accumulation of fat due to obesity or diabetes.

• Viral Hepatitis: Inflammation of the liver due to infections caused by hepatitis viruses A, B, C, and D.

• Drug-Induced Hepatitis: Inflammation (swelling) of the liver due to intake of medications like Acetaminophen. They damage the liver tissues and cause liver dysfunction.

• Liver Carcinoma: Abnormal cancer tissue growth in the liver.

• Cirrhosis: The healthy liver tissues are replaced by scarring tissue. This results due to excess alcohol consumption for many years.

What Factors Affect the Liver Function?

• Intake of certain medications like Acetaminophen frequently or beyond the prescribed time or dose.

• Taking medication containing estrogen or oral contraceptive pills for a long time.

• Alcohol consumption.

• Illegal drug usage.

• Being obese or overweight.

• Viral infection.

How to Maintain a Healthy Liver?

• Following a healthy diet includes proteins, vitamins, carbohydrates, and fibers in equal proportions.

• Maintain an average body weight by exercising regularly.

• Take prescribed medications for the prescribed duration only.

• Avoid taking over-the-counter medications (medications that do not need a prescription) without a physician’s advice.

• Practice safe sex to avoid contracting hepatitis C infection.

• Do not share needles, and use a sterile needle.

• Avoid consuming too much alcohol.

• Avoid eating junk foods and deep-fried foods.

Conclusion:

The liver is a significantly important organ present on the right side of the upper abdominal region above the stomach. The liver takes part in blood purification and aids digestion. In addition, the liver performs important functions like managing blood clotting, processing sugar, and fighting against infections. If any of the functions are not performed correctly, it will result in liver damage or liver disease. Therefore, it is essential to maintain the liver healthy to avoid liver disease and complications. The unique feature of the liver is that it regenerates or regrows naturally after an injury or damage. The liver is a major organ in our human body, and taking care of the liver with healthy habits paves the way for a healthy and long life.