Liver

Anatomy

Largest organ other than skin, largest gland, c. 1.5-3 kg, 4 lobes (left, right, caudate, quadrate), triangular, right upper quadrant abdomen under diaphragm.

Hilum (or porta hepatis) is a fissure under left lobe, through which dual blood supply enters (hepatic portal vein from GI system, hepatic artery from celiac from aorta) and common bile duct (2 right and 1 left hepatic ducts join, form common hepatic duct, joined by cystic duct of gall bladder, forming common bile duct) leaves (and is joined by pancreatic duct at ampulla of Vater at doudenum).

Blood leaves through hepatic vein to adjacent inferior vena cava.

Clinical

Anatomical unit is hexagonal lobule; portal triads (portal vein, artery, bile duct) each corner, connected by sinusoids lined by single rows of hepatocytes, to a central vein. Metabolic unit is diamond-shaped acinus; 2 adjacent portal triads and 2 adjacent central veins.

2 main cell types; parenchymal (hepatocytes, 80%) and non-parenchymal (20%, including Kupffer macrophages and endothelial).

Liver performs multiple functions: forms and stores glycogen from glucose and releases glucose as needed; further breaks down and processes nutrients absorbed in gut; makes bile to assist digestion particularly of fat; detoxifies blood of eg old cells, proteins, hormones; makes proteins including those needed for blood coagulation (clotting).

Vignette

Liver diseases include: infection, such as viral hepatitis (including A, B, C); inflammatory, such as alcohol and drug-induced (including acetaminophen); cirrhosis, with scar formation with nodules and acinar/lobular disruption; hemochromatosis, inherited condition, with excessive absorption and build-up of iron; cancer, primary (usually following chronic hepatitis) and – more usually – secondary (through metastatic spread from breast, colorectal, esophageal, lung, melanoma, pancreatic, stomach and others).

Symptoms of hepatic disease include; jaundice (yellowish skin and eyes), abdominal pain/swelling, itchiness, dark urine and pale stool, fatigue, loss of appetite, nausea.

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