| | Cancer | Liver Cancer
Hepatic Lobule: The Liver's Functional Unit — Structure and Metabolic Roles
Histologic Architecture
- Shape: Roughly hexagonal.
- Center: Central vein (terminal hepatic venule).
- Periphery: Portal triads (hepatic artery, portal vein, bile duct) at each corner.
- Plates: Hepatocyte cords radiate from central vein; sinusoids between plates.
- Blood flow: Portal vein (75%) + hepatic artery (25%) → sinusoids → central vein → hepatic veins → IVC.
- Bile flow: Opposite direction: hepatocyte canaliculi → bile ductules → bile ducts.
Functional Zonation (Rappaport)
- Zone 1 (periportal): Oxygen/nutrient-rich; oxidative metabolism, gluconeogenesis, β-oxidation, urea cycle, bile synthesis.
- Zone 2 (midzonal): Intermediate.
- Zone 3 (pericentral): Low oxygen; glycolysis, lipogenesis, CYP450 detoxification, glutamine synthesis.
Key Hepatocyte Functions
| Category | Processes |
|---|---|
| Carbohydrate | Glycogenesis, glycogenolysis, gluconeogenesis, glycolysis |
| Lipid | β-oxidation, ketogenesis, lipogenesis, VLDL assembly, cholesterol synthesis |
| Protein | Albumin, clotting factors, acute-phase proteins, urea cycle |
| Detoxification | Phase I (CYP450), Phase II (conjugation), ammonia → urea |
| Bile | Bile acid synthesis, secretion, bilirubin conjugation |
| Storage | Glycogen, vitamins A/D/B12/K, iron (ferritin), copper |