Liver

What is the liver?

The largest organ in the abdomen, weighing approximately 3 pounds, located inferior to the diaphragm. It performs metabolic regulation, hematologic regulation, and bile production.

What is Glisson's capsule?

A fibrous capsule that encases the liver and contains nerves, blood vessels, and lymphatic vessels.

Which parts of the liver are not covered by peritoneum?

The gallbladder fossa, the surface apposed to the IVC, and the bare area located between the superior and inferior coronary ligaments.

What are the major functions of the liver?

Bile production, storage, nutrient interconversion, detoxification, phagocytosis, and synthesis of important proteins and clotting factors.

What is bile?

A fluid composed of bile salts, cholesterol, bilirubin, water, and electrolytes that aids digestion and fat absorption.

What is the role of bile salts?

They break down and emulsify fats to aid digestion and absorption.

Does bile contain digestive enzymes?

No. Bile contains no digestive enzymes but helps digestion by emulsifying fats and neutralizing stomach acid.

What substances are stored in the liver?

Glycogen, fat, vitamins A, B12, D, E, and K, copper, and iron.

What is nutrient interconversion?

The liver's ability to convert excess glucose into fat and amino acids into glucose through gluconeogenesis.

What is gluconeogenesis?

The process by which the liver converts amino acids into glucose when blood sugar levels are low.

How does the liver detoxify the body?

Hepatocytes remove toxic ammonia produced during protein metabolism and convert it into urea for excretion by the kidneys.

What are Kupffer cells?

Specialized hepatic macrophages that engulf bacteria, worn-out red blood cells, and white blood cells.

What proteins are synthesized by the liver?

Albumin, fibrinogen, globulins, heparin, and other clotting factors.

What is albumin?

A protein synthesized by the liver that helps maintain blood volume and osmotic pressure.

What is fibrinogen?

A liver-produced protein essential for blood clotting.

What are liver lobules?

Hexagonal-shaped structural and functional units of the liver; the liver contains approximately 50,000–100,000 lobules.

What cells make up the hepatic plates?

Hepatocytes.

What is the central vein?

A vein located in the center of each liver lobule into which blood eventually drains.

What is a portal triad?

A group of three structures found at each corner of a liver lobule consisting of a bile duct, hepatic artery, and portal vein.

What structures make up the portal triad?

Bile duct, hepatic artery, and hepatic portal vein.

What is the sonographic appearance of the portal triad?

The "Mickey Mouse" appearance.

What is the function of the hepatic artery in the portal triad?

To supply oxygen-rich blood to the liver.

What is the function of the hepatic portal vein?

To carry nutrient-rich venous blood from the digestive tract to the liver.

What are liver sinusoids?

Enlarged, leaky capillaries located between hepatic plates.

Where are Kupffer cells found?

Within the liver sinusoids.

What are the primary functions of hepatocytes?

Bile production, nutrient processing, vitamin storage, and detoxification.

How does bile leave the liver?

Through the right and left hepatic ducts, which join to form the common hepatic duct.

What forms the common bile duct?

The union of the common hepatic duct and cystic duct.

What is the porta hepatis?

A central area on the underside of the liver where major vessels and ducts enter and exit.

What structure anchors the liver to the stomach?

The lesser omentum.

Where is the gallbladder located in relation to the liver?

In a recess on the inferior surface of the right lobe.

Which liver lobe is the most superior and anterior?

The left lobe.

What landmark separates the left lobe from the right lobe anteriorly?

The falciform ligament.

Where is the caudate lobe located?

Posterosuperior liver surface between the IVC and ligamentum venosum.

Which liver lobe is the smallest?

The caudate lobe.

Where is the quadrate lobe located?

On the anteroinferior surface of the left lobe between the gallbladder fossa and ligamentum teres.

Which liver lobe is the largest?

The right lobe.

How much larger is the right lobe compared to the left lobe?

Approximately six times larger.

What separates the right and left lobes functionally?

The main lobar fissure (Cantlie line).

What are the three fossae of the right lobe?

Porta hepatis, gallbladder fossa, and IVC fossa.

What is the coronary ligament?

A horizontal peritoneal duplication whose lateral margins form the right and left triangular ligaments.

What is the falciform ligament?

A ligament attaching the liver to the diaphragm and anterior abdominal wall while separating the right and left lobes anteriorly.

What is the ligamentum teres?

A remnant of the fetal umbilical vein located within the free edge of the falciform ligament.

What is the ligamentum venosum?

A ligament separating the left lobe from the caudate lobe.

What does the falciform ligament separate?

The right and left lobes of the liver.

What does the ligamentum venosum separate?

The left lobe from the caudate lobe.

What is the main lobar (interlobar) fissure?

A fissure associated with the gallbladder that divides the liver into right and left lobes.

What is the umbilical fissure?

The fissure for the ligamentum teres that divides the left lobe into medial and lateral segments.

What is the transverse (portal) fissure?

A fissure that divides the right lobe into anterior and posterior segments.

What is the fissure for ligamentum venosum?

A fissure separating the caudate lobe from the left lobe.

Who developed the Couinaud classification system?

French surgeon Claude Couinaud in the 1950s.

How many functional liver segments are recognized in the Couinaud classification?

Eight segments.

What is Segment I?

Caudate lobe.

What is Segment II?

Left lateral superior segment.

What is Segment III?

Left lateral inferior segment.

What is Segment IVa?

Left medial superior segment.

What is Segment IVb?

Left medial inferior segment.

What is Segment V?

Right anterior inferior segment.

What is Segment VI?

Right posterior inferior segment.

What is Segment VII?

Right posterior superior segment.

What is Segment VIII?

Right anterior superior segment.

Which hepatic vein divides the liver into right and left lobes?

The middle hepatic vein.

Which hepatic vein divides the right lobe into anterior and posterior sections?

The right hepatic vein.

Which hepatic vein divides the left lobe into medial and lateral sections?

The left hepatic vein.

How are liver segments supplied?

Each segment has its own portal triad and hepatic vein, making it independently functional.

What is the function of the hepatic veins?

They collect deoxygenated blood from the liver and drain it into the IVC.

Which are the three major hepatic veins?

Right, middle, and left hepatic veins.

Which hepatic vein is the largest?

The right hepatic vein.

Which hepatic vein is the smallest?

The left hepatic vein.

Where does the IVC lie in relation to the liver?

In a groove along the posterior surface of the liver.

What is the portal vein?

A vessel carrying nutrient-rich, deoxygenated blood from the gastrointestinal tract, spleen, and pancreas to the liver.

What percentage of liver blood flow is supplied by the portal vein?

Approximately 70%.

How is the main portal vein formed?

By the union of the splenic vein (SV) and superior mesenteric vein (SMV).

What is the normal diameter of the main portal vein?

Up to 13 mm.

Into what branches does the left portal vein divide?

Medial and lateral branches.

Into what branches does the right portal vein divide?

Anterior and posterior branches.

What is the function of the hepatic artery?

To supply oxygenated blood to the liver.

What artery gives rise to the common hepatic artery?

The celiac trunk.

What are the three branches of the celiac trunk?

Splenic artery, left gastric artery, and common hepatic artery.

What are the two branches of the common hepatic artery?

Gastroduodenal artery (GDA) and proper hepatic artery (PHA).

What are the two branches of the proper hepatic artery?

Right hepatic artery and left hepatic artery.

What conditions may require a liver ultrasound?

Suspected hepatomegaly, masses, abscesses, metastatic lesions, portal hypertension, thrombosis, ascites, pleural effusion, and transplant evaluation.

What imaging modalities are commonly used to evaluate the liver?

CT, MRI, angiography, radionuclide scintigraphy, and liver biopsy.

What laboratory tests are commonly included in liver function tests (LFTs)?

Albumin, bilirubin, ALP, AST, ALT, beta globulin, gamma globulin, LDH, protein, cholesterol, and prothrombin time.