The body's biochemical headquarters. The liver processes every nutrient the gut sends, stores and releases fuel, detoxifies what the body cannot use, and makes the plasma proteins blood needs.
The liver's functional unit is the lobule: plates of hepatocytes between portal triads and central veins, blood filtering past cells in one direction while bile runs the other way. This dual flow — nutrient-rich portal blood in, bile out — makes the organ both the body's chemical plant and its exocrine gland; the biliary half is covered at liver (exocrine). Regeneration is its superpower: resection of two-thirds regrows within weeks.
Metabolic Pathways
Glucose homeostasis: glycogen buffer hours after meals, then gluconeogenesis for fasting brain — with glucokinase and PDH as gate enzymes.
Amino acid disposal: transamination via ALT, then urea synthesis for safe nitrogen export.
Lipid traffic: VLDL assembly, cholesterol synthesis, ketogenesis in fasting via ketone body synthesis.
Regulation
The insulin-glucagon ratio flips the organ between storing and releasing — see the homeostasis pathway.
Portal insulin delivery gives the liver first word on every meal's nutrients.
Xenobiotic enzymes — cytochrome P450s — induce and repress by exposure.
Interactions
Receives the gut's output via the portal vein and ships glucose to the brain and muscle.
Hepatitis B and C, alcohol, and fatty liver disease are the big four worldwide.
Liver function tests — ALT, bilirubin, albumin, INR — read the factory's gauges.
The organ's dual blood supply — portal plus arterial — protects it: either alone can sustain the tissue.
Endocrine Functions
Content consolidated from the former Liver (Endocrine) page.
Portal position: it degrades insulin on first pass, shaping what the periphery sees — see the islets upstream.
With the kidney: renin acts on the liver's angiotensinogen — a two-organ hormone system.
Vitamin D carrier and activation partner to the kidney's calcitriol step.
Cirrhosis reshapes endocrinology: gynecomastia, low SHBG, altered drug and hormone clearance.
IGF-1 is the follow-up marker for acromegaly — the liver as assay of growth hormone excess.
Hepatic thrombopoietin loss contributes to cirrhotic thrombocytopenia — a platelet count that reads liver function.
Sex-hormone binding globulin made here sets testosterone and estrogen availability: thyroid and liver status shift free hormone without changing production.