Hepatic System

肝脏 · 化学工厂

Place · Level 3

1.5 kg · 500+ 化学反应 · 双血供 · Phase I 拆分子 + Phase II 装把手 · NAFLD 全球第一肝病 · 排毒99% 是营销

Connected to · 10

synergy · 1

Kidney
Drug metabolism: liver Phase I/II metabolites are mostly renally excreted. Hepatic or renal impairment burdens the other — combined pharmacokinetics is the core risk in polypharmacy.

cofactor · 1

Selenium
Glutathione only neutralises peroxides through glutathione peroxidase (GPx), whose catalytic centre is a selenocysteine — there is a selenium atom embedded in the liver's busiest detox line.

regulates · 7

Digestive
The liver produces ~600 mL bile daily; gut FXR receptors feed bile-acid reabsorption signals back. In NASH, disrupted enterohepatic signaling is the key second hit.
Heart
Liver is the lipid hub: VLDL export → peripheral fat deposition; NASH patients carry 2-3× CVD risk. 'Fatty liver is not just a liver problem' has a molecular basis.
Type 2 Diabetes
Taylor twin cycle: NAFLD (hepatic TG >5%) → VLDL output ↑ → ectopic lipid deposition in pancreatic islets → β-cell decline → T2D. DiRECT reverses in this order: hepatic TG drops 30% in week 1, normalises by week 8; pancreatic TG normalises by week 12.
Digestive
Portal blood feeds liver directly → gut-microbial products (LPS, SCFA, secondary bile acids) are major hepatic metabolic + inflammatory signals. NAFLD two-hit model: hepatic fat + gut-derived LPS → NASH progression.
Alcohol Metabolism
Chronic drinking induces CYP2E1. That route generates ROS which keeps damaging the liver, and it pushes acetaminophen toward its toxic metabolite — so a chronic drinker can reach acute liver failure on a normal dose of the painkiller.
Endocrine
Liver converts T4→T3, produces IGF-1 (GH downstream), and is the first site of insulin resistance — 'obesity + fatty liver + hormone dysregulation' are three chapters of one metabolic story.
Immune
Liver-resident Kupffer cells are the body's largest fixed macrophage pool — in NASH, gut-derived LPS activates Kupffer → NF-κB → inflammatory liver injury. The liver also produces CRP and acute-phase proteins amplifying systemic inflammation.

contrast · 1

Milk Thistle
Milk thistle is the commonest ingredient on the liver-pill shelf, yet the liver's own phase I/II clearance workshop already runs continuously, and pooled randomized trials show no effect on mortality or complications of liver disease.

Lobule · dual blood supply

Stop 1/6

肝小叶 · 双血供

The liver's position in the body is unusual: 1.2-1.5 kg (~2.5% body weight), runs 500+ known chemical reactions, regenerates 70% in 6 months. Only one organ combines all three.

It's also one of few organs with a dual blood supply:

Portal vein provides ~75% of flow — nutrient-rich, draining stomach, intestines, pancreas, spleenHepatic artery provides ~25% — oxygen-rich, from the heart
The two streams converge in hepatic sinusoids, flow slowly past hepatocytes, then exit via central vein → hepatic vein → IVC → heart.

This architecture means almost everything you eat (except some fat that bypasses via lymph) passes through the liver first — the first-pass effect. Several clinical phenomena follow:

Oral drugs typically have lower bioavailability than IV — a fraction is metabolized in the first passIn liver disease, blood ammonia rises (intestinal bacterial NH3 is normally cleared by liver)Postprandial glucose peaks are buffered by liver first — the liver grabs 50-70% of portal-vein glucose for glycogen
The functional unit is the lobule, a ~1 mm hexagonal structure: central vein at the center, six corners each holding a portal triad (portal vein branch + hepatic artery branch + bile duct), hepatocytes arranged in plates, sinusoids between them. Kupffer cells, resident macrophages, sit along sinusoids phagocytosing gut-derived debris and senescent red cells.

Hepatocytes also show zonation from portal triad to central vein, Zones 1-3. Zone 1 is oxygen-rich and handles gluconeogenesis, β-oxidation, detox; Zone 3 is hypoxic, runs glycolysis, fat synthesis, alcohol and drug metabolism — which is why alcohol and drug injury always damage Zone 3 first.

Read story

Educational content, not medical advice — consult a clinician.

Back