Central vein
Collects sinusoidal blood and drains toward hepatic veins.
GI
Liver Tissue Architecture
Read the lobule by direction: blood drains inward, bile runs outward, and oxygen loss deepens toward zone 3.
- Trace blood and bile through the hepatic lobule
- Identify Kupffer and stellate-cell functions
- Predict zonal injury from oxygen and cytochrome P450 gradients
Anatomic relationships
Use the landmarks before naming the lesion
The figure shows the location and nearby structures that distinguish the diagnosis.
Quick check
After a large acetaminophen overdose, necrosis clusters around central veins, where cytochrome P450 activity is high and oxygen tension is low.
Which acinar zone contains the injured hepatocytes?
Reason it through
- Where is the necrosis centered?It surrounds central veins in the pericentral region.
- Which local metabolic feature increases toxic injury?Zone 3 has the highest cytochrome P450 activity.
Read the classic lobule
Anchor a classic lobule at the central vein, then read portal tracts at its edges.
A central vein occupies the middle of a classic lobule. Portal tracts at the perimeter contain portal venous, hepatic arterial, and bile-duct branches plus lymphatics and nerves.
Hepatocyte plates radiate inward between fenestrated sinusoids lined by endothelial cells and Kupffer macrophages.
Between sinusoidal endothelium and hepatocytes, the space of Disse supports exchange with basolateral microvilli and houses stellate cells.
Open each lobular compartment.
Portal triad
Portal venule, hepatic arteriole, and bile ductule plus lymphatics and nerves.
Sinusoid
Low-pressure mixed blood channel between hepatocyte plates.
Space of Disse
Perisinusoidal exchange space containing stellate cells.
Bile canaliculus
Tiny channel between hepatocyte apical surfaces carrying bile toward portal tracts.
Zones 1, 2, and 3
The acinus recasts lobular anatomy as a gradient of oxygen delivery and metabolic work.
Nearest portal triads, zone 1 receives hepatic-arterial oxygen and portal nutrients first and tolerates reduced perfusion best.
Zone 2 is intermediate; yellow-fever injury classically produces a midzonal pattern, although many diseases cross zonal boundaries.
Closest to central veins, zone 3 receives blood last, carries abundant cytochrome P450 activity, and is most vulnerable to ischemia and reactive metabolites.
Switch among the acinar zones.
Highest oxygen; first exposure to incoming blood; oxidative metabolism, gluconeogenesis, urea cycle.
Mid-acinar transition; classically highlighted in yellow fever.
Lowest oxygen; highest P450 activity; ischemia, acetaminophen, carbon tetrachloride, and alcoholic injury patterns.
Zone 1 receives blood first; zone 3 runs out of oxygen first.
Blood and bile flow in opposite directions
Portal tracts launch blood inward while canaliculi carry bile back toward portal ducts.
Portal venous and hepatic arterial branches deliver mixed blood from the lobular edge into sinusoids.
After crossing hepatocyte plates, sinusoidal blood drains into central veins, then hepatic veins, and finally the inferior vena cava.
Bile enters canaliculi and flows away from central veins toward bile ductules in portal triads, opposite sinusoidal blood.
Reveal both flow paths.
- Portal vein and hepatic artery branchesTwo inflows enter at the lobular periphery.
- SinusoidsMixed blood flows between hepatocyte plates.
- Central veinSinusoids converge at the lobular center.
- Hepatic veins and inferior vena cavaCentral venous blood exits the liver.
- Bile canaliculi run the opposite wayHepatocytes send bile toward ductules in portal triads.
Stellate cells store vitamin A and make scar
A perisinusoidal vitamin A reservoir becomes the main scar producer after chronic injury.
Quiescent hepatic stellate, or Ito, cells occupy the space of Disse and store vitamin A in lipid droplets.
Chronic inflammatory or toxic injury turns stellate cells into contractile matrix producers that deposit collagen and drive hepatic fibrosis.
Fibrosis within the space of Disse also interferes with exchange between sinusoidal plasma and hepatocyte basolateral surfaces.
Which cell is the main collagen-producing effector in hepatic fibrosis?
Rate confidence before committing.
Ito cells store vitamin A until injury converts them into scar-forming cells.
Oxygen falls from portal tract to central vein
Each pass through sinusoids consumes oxygen before blood reaches the lobular center.
At the acinar entrance, portal triads supply hepatic-arterial oxygen together with portal venous nutrients.
Oxygen extraction along sinusoids creates a gradient, leaving pericentral hepatocytes with the least reserve during hypotension or venous congestion.
Classify each region by relative oxygen delivery.
Zone 1 periportal
Zone 2 intermediate
Zone 3 pericentral
Central-vein edge during shock
By the time blood reaches the central vein, zone 3 has received the oxygen that remains.
The cellular cast
Position separates the liver's processing, immune, exchange, and bile-duct roles.
Hepatocytes face sinusoidal plasma with basolateral surfaces and sealed bile canaliculi with apical surfaces, allowing blood processing and bile secretion at once.
Resident Kupffer macrophages clear microbes, debris, and senescent cells from portal blood while coordinating inflammatory responses.
Fenestrated sinusoidal endothelium permits plasma exchange without a normal basement-membrane barrier, whereas cholangiocytes line and modify the bile-duct system.
Open each cell and its job.
Metabolism, detoxification, protein synthesis, bilirubin handling, and bile formation.Resident macrophage in sinusoids clearing bacteria, debris, and damaged cells.Vitamin A storage when quiescent; extracellular-matrix production when activated.Fenestrated barrier supporting exchange between plasma and hepatocytes.Epithelial cell lining bile ducts and modifying ductular bile.
Stage 1 of 3: Overview
Overview
Liver Tissue Architecture
Portal tracts launch blood inward while canaliculi carry bile back toward portal ducts.
Localization check
Which landmark matters most?
Choose the location that rules the other answer choices in or out.
Which acinar zone contains the injured hepatocytes?
- Key finding. around central veins
- Answer. Zone 3
- Why. Pericentral zone 3 has the highest P450 activity and the lowest oxygen reserve, making it vulnerable to reactive metabolites.
- Board rule. Pericentral necrosis after acetaminophen exposure localizes to zone 3, where P450 activity is highest and oxygen reserve is lowest.
Navigate hepatic microanatomy
Five tasks move from ischemic injury to fibrogenic cells, sinusoidal flow, and central-vein identification.
Cross out wrong locations and highlight the decisive landmark. Each case connects anatomy to its clinical consequence.
Prolonged hypotension is followed by marked aminotransferase elevation; biopsy shows centrilobular necrosis.
Which acinar zone lost oxygen first?
Reason it through
- Where does the biopsy place the injury?The necrosis is centrilobular, adjacent to central veins.
- Which zone receives oxygenated blood last?Zone 3 sits farthest from portal inflow and receives the least remaining oxygen.
- Why is zone 1 less likely in low-flow injury?Zone 1 receives oxygenated blood first and is most resistant to reduced perfusion.
centrilobular necrosisWhich zone receives oxygenated blood last?
- Where does the biopsy place the injury?The necrosis is centrilobular, adjacent to central veins.
- Which zone receives oxygenated blood last?Zone 3 sits farthest from portal inflow and receives the least remaining oxygen.
- Why is zone 1 less likely in low-flow injury?Zone 1 receives oxygenated blood first and is most resistant to reduced perfusion.
In chronic hepatitis, cells in the space of Disse activate and begin depositing collagen.
Which resident cell became fibrogenic?
Reason it through
- Which compartment contains the activated cells?They reside in the perisinusoidal space of Disse.
- What is their quiescent storage role?Hepatic stellate, or Ito, cells store vitamin A in lipid droplets.
- How does chronic injury change their function?They become matrix-producing cells that deposit collagen and drive fibrosis.
space of DisseWhat is their quiescent storage role?
- Which compartment contains the activated cells?They reside in the perisinusoidal space of Disse.
- What is their quiescent storage role?Hepatic stellate, or Ito, cells store vitamin A in lipid droplets.
- How does chronic injury change their function?They become matrix-producing cells that deposit collagen and drive fibrosis.
A tracer is injected into a small portal-vein branch within a portal triad.
Which route does the tracer enter next?
Reason it through
- Is the injected vessel an inflow or an outflow?A portal venous branch delivers blood at the lobular edge.
- Which channels receive mixed portal and arterial blood?Sinusoids carry the mixed blood between hepatocyte plates.
- Where do those channels converge?They drain toward the central vein.
portal-vein branchWhich channels receive mixed portal and arterial blood?
- Is the injected vessel an inflow or an outflow?A portal venous branch delivers blood at the lobular edge.
- Which channels receive mixed portal and arterial blood?Sinusoids carry the mixed blood between hepatocyte plates.
- Where do those channels converge?They drain toward the central vein.
A histology section shows a vessel at the lobular center that collects sinusoidal blood and drains toward hepatic veins.
Which structure is labeled?
Reason it through
- Where is the vessel positioned within the lobule?It lies at the center of the classic lobule.
- Which upstream channels empty into it?Sinusoids converge on the central vessel.
- Where does its blood travel afterward?Drainage toward hepatic veins identifies the structure as the central vein.
collects sinusoidal bloodWhich upstream channels empty into it?
- Where is the vessel positioned within the lobule?It lies at the center of the classic lobule.
- Which upstream channels empty into it?Sinusoids converge on the central vessel.
- Where does its blood travel afterward?Drainage toward hepatic veins identifies the structure as the central vein.
A blood-flow diagram has reached the sinusoids between hepatocyte plates.
Which structure receives the blood next?
Reason it through
- Which way does sinusoidal blood move through a classic lobule?It moves from portal tracts at the edge toward the lobular center.
- What vessel sits at that center?The central vein collects the converging sinusoidal flow.
- What lies downstream from that vessel?Central venous blood continues to hepatic veins and the inferior vena cava.
sinusoidsWhat vessel sits at that center?
- Which way does sinusoidal blood move through a classic lobule?It moves from portal tracts at the edge toward the lobular center.
- What vessel sits at that center?The central vein collects the converging sinusoidal flow.
- What lies downstream from that vessel?Central venous blood continues to hepatic veins and the inferior vena cava.
Rapid review
Three questions to check
Which acinar zone contains the injured hepatocytes?
Zone 3. Pericentral zone 3 has the highest P450 activity and the lowest oxygen reserve, making it vulnerable to reactive metabolites.
Where does the biopsy place the injury?
The necrosis is centrilobular, adjacent to central veins.
Which zone receives oxygenated blood last?
Zone 3 sits farthest from portal inflow and receives the least remaining oxygen.
Medically reviewed
Fatima Ali, DO
PGY-1 Resident Physician in Psychiatry
University Hospitals, Columbia
DO from Kansas City University
Resident physician and founding medical reviewer at Bone Wizardry, focused on clinical accuracy, clear diagnostic reasoning, and practical board-oriented teaching across the curriculum.
Languages: English, Urdu
Primary reviewerFull physician profile
Medically reviewed
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Bone Wizardry is a study resource for medical students. It is not medical advice.