8.3 Liver and Gall Bladder

Liver Functions

• The liver is crucial for many metabolic activities, including:

  • Carbohydrate metabolism:

  • Stores glycogen.

  • Lipid metabolism:

  • Stores fats.

  • Protein metabolism:

  • Synthesizes most plasma proteins.

  • Storage of vitamins and minerals:

  • For example, stores Vitamin A.

  • Detoxification:

  • Breaks down toxic substances such as alcohol.

  • Nutrient processing:

  • All nutrients, except fats, from the gastrointestinal tract are conveyed to the liver via the portal vein.

  • Bile secretion:

  • Important for digestion of fats.

Liver Structure

• The liver is the largest organ in the body, comprising about 2% of body weight:

  • Average weight:

  • Females: ~1400 g

  • Males: ~1800 g

• Palpation:

  • Only the inferior margin (thin edge) is palpable in a healthy individual.

• Anatomical structures:

  • Divided into 4 lobes:

  • Right lobe (larger)

  • Left lobe

  • Caudate lobe

  • Quadrate lobe

  • Falciform ligament:

  • Attaches the liver to the anterior wall, divides left, right

  • Bare area:

  • Part of the liver with no peritoneum covering.

• Lobular structure:

  • Functional units are lobules. Each lobule contains acini, which are ellipsoid areas of hepatocytes.

Blood Supply to the Liver

• Porta Hepatis (hilum) - door through which blood vessels, nerves and
  ducts enter and leave the liver, contains

• Dual blood supply:

  • Portal Vein:

  • Carries 70% of blood to the liver.

  • Deoxygenated blood with nutrients from the gastrointestinal tract.

  • Hepatic Arteries:

  • Carry 30% of oxygenated blood to the liver.

  • Branch from the celiac trunk.

• Venous Drainage:

  • Blood is drained from the liver via hepatic veins into the inferior vena cava (IVC).

Lymphatics and Nerves

• The liver produces a major portion of lymph in the body (around 40% of thoracic duct lymph originates here) via lymphatic vessels

• Nerve supply: hepatic nerve plexus

  • Parasympathetic: Vagus nerve (CN X)

  • Sympathetic: Splanchnic nerves.

Gallbladder Functions

• The gallbladder:

  • Stores and concentrates bile( fluid used for digestion).

  • Releases bile to emulsify fats during digestion.

Anatomy of the Gallbladder

• The gallbladder is connected to the liver by a system of ducts:

  • Right and Left Hepatic Ducts ➜ Common Hepatic Duct ➜ Cystic Duct ➜ Gallbladder

  • Bile flows from the gallbladder to the duodenum.

Blood Supply and Lymphatics of the Gallbladder

• Most blood supply comes from the cystic artery (a branch of the right hepatic artery which arises from the common hepatic artery).

• Venous drainage:

  • Directly into the liver via short venules.

• Lymphatics drain into cystic lymph node of Lund located in the Calot triangle.

Innervation of the Gallbladder

• Innervation is from:

  • Right phrenic nerve: Sensory function.

  • Hepatic branch of the right vagus nerve: Parasympathetic innervation.

  • Celiac plexus: Sympathetic function.

• Surgical impacts:

  • Procedures such as vagotomy can lead to gallbladder dysfunction, causing formation of gallstones and potential cholecystitis.

Summary of Key Points

• The liver's roles include metabolism, vitamin storage, substance breakdown, and bile production.

• The gallbladder functions to concentrate and store bile.

• Liver anatomy features 4 lobes with a hilum (porta hepatis) and a dual blood supply from the portal vein and hepatic arteries.

• Liver lobes are made of functional units (lobules) containing acini, which are critical for liver function.

• Bile produced by the liver travels through ducts to the gallbladder, then to the duodenum as needed for fat digestion.