What Is the Liver?

The liver is the largest solid organ in the human body and a central node in metabolic, digestive, and immune function. Located in the upper right quadrant of the abdomen, it accounts for approximately 2 to 3 percent of total body weight in adults and performs over 500 distinct physiological tasks. In biomedical engineering, the liver is studied as a complex vascular-metabolic structure whose anatomy, hemodynamics, and cellular organization inform the design of diagnostic tools, surgical planning systems, and regenerative therapies.

The organ draws its importance in part from its dual blood supply: approximately 75 percent of inflow arrives through the portal vein, carrying nutrient-rich blood from the gastrointestinal tract, while the remaining 25 percent enters through the hepatic artery, which delivers oxygenated blood from the systemic circulation. This vascular architecture makes the liver uniquely sensitive to both digestive output and systemic conditions, and it is described in detail in research on hepatic vascular structure published in Scientific Reports.

Hepatic Structure and Vasculature

The functional unit of the liver is the hepatic lobule, a roughly hexagonal structure approximately one millimeter in diameter. Each lobule is organized around a central vein, with portal triads at each corner containing a branch of the portal vein, a branch of the hepatic artery, and a bile duct. Hepatocytes, the primary liver cells, are arranged in radial plates between these vessels. Blood flows from the portal triads inward toward the central vein, allowing hepatocytes along the way to extract nutrients, process toxins, and synthesize proteins. Bile flows in the opposite direction, collecting in the canaliculi and draining toward the bile ducts. This counter-current organization is foundational to models used in computational fluid dynamics simulations of hepatic perfusion.

Metabolic and Synthetic Functions

The liver regulates glucose homeostasis through glycogenesis, glycogenolysis, and gluconeogenesis, adjusting circulating glucose levels in response to insulin and glucagon signals. It synthesizes nearly all plasma proteins, including albumin, clotting factors, and acute-phase reactants, and it produces bile acids required for fat digestion. The organ also handles xenobiotic metabolism: cytochrome P450 enzymes in hepatocytes convert drugs, environmental toxins, and endogenous compounds into water-soluble forms for renal excretion. The breadth of these functions is described in the NIH StatPearls entry on liver physiology, which covers the key enzymatic pathways in detail.

Biomedical Engineering and Liver Research

Engineering approaches to the liver span imaging, tissue engineering, and organ-on-chip modeling. Segmentation algorithms applied to CT and MRI scans can delineate the liver's eight Couinaud segments, enabling surgeons to plan resections based on predicted residual volume and vascular territories. Microfluidic platforms recreate the hepatic sinusoid environment in vitro, supporting drug toxicity screening and disease modeling. Three-dimensional bioprinting with hepatocyte-laden hydrogels is under investigation as a path toward implantable liver tissue. A review of these methods is presented in PMC research on bioengineering of the liver, covering scaffolding materials, organoid cultures, and decellularization strategies.

Applications

The liver is a focus of research and clinical technology in a range of biomedical disciplines, including:

• Surgical planning software for hepatic resection and transplant evaluation
• Computer-aided diagnosis of focal liver lesions in CT and MRI scans
• Liver-on-chip platforms for pharmaceutical toxicity screening
• Tissue engineering and organoid models for regenerative medicine
• Computational hemodynamic simulation of portal hypertension