Liver and Gallbladder
Objective 7
Describe or identify on a diagram the gross anatomy of the liver: liver lobes, coronary ligament, falciform ligament, round ligament (ligamentum teres). Identify on a diagram and be able to describe the function of the cells and structures in a liver lobule: hepatocytes, Kupffer cells, hepatic sinusoids, bile canaliculi, central vein, portal triad (hepatic triad). Describe or identify on a diagram the structures associated with bile production, storage and release: hepatic duct, cystic duct, gallbladder, common bile duct, sphincter of the ampulla. Explain how each structure is involved in the production, storage and release of bile. Diagram the enterohepatic circulation of bile salts.
The liver is tied with the brain for the title “second-largest organ of the body”. Do you recall which organ is larger?
Grossly, the liver is divided into four lobes. The right and left lobes are visible from the anterior (ventral) surface of the body. The caudate (Latin: “tail-shaped”) and quadrate (Latin: “square”) lobes are only seen when looking from the posterior or inferior surfaces.
The liver is held in place by three strips of connective tissue (ligaments). The falciform ligament (Latin: “sickle-shaped”), the coronary ligament, and the round ligament (also called by its Latin name, ligamentum teres). The falciform ligament and coronary ligament both attach to the diaphragm, which keeps the liver in a position in the superior part of the abdominal cavity and mostly to the right side of the body.
The liver has a close relationship to its neighbors in the abdominal cavity: the pancreas, and the duodenum. These three organs work together, as we’ll see.
The liver’s blood supply is different than most other organs. The cells of the liver, like any other cells of the body, need oxygen and glucose, and they get oxygenated blood from the left ventricle of the heart, via the aorta, and abdominal aorta, to the hepatic artery (also called proper hepatic artery).
A second source of blood to the liver is related to its function as a detoxification and energy storage organ. This supply comes from the venous drainage of the stomach and intestines, through a vessel called the hepatic portal vein. This brings glucose-rich but oxygen-poor blood from the absorptive cells of the digestive organs to the liver for processing.
The venous drainage of the liver is through hepatic veins to the inferior vena cava and thence to the right atrium of the heart.
Blood Flow Through Liver
In order to carry out its functions of blood cleansing and nutrient metabolism, the liver routes blood through functional units called liver lobules. Blood from the hepatic artery and hepatic portal vein is passed alongside the cells of the liver, and then collects in small central veins which gather from the entire liver to form the hepatic vein.
For years, physiologists have assumed that the hexagonal (six-sided) hepatic lobule is the functional unit of the liver. That’s