A healthy human liver is a large, reddish-brown organ with a smooth, glossy surface. It weighs about 1,500 grams (roughly 3.3 pounds) in an average adult, making it the largest solid organ in the body. Shaped somewhat like a wedge or a flattened football, it sits in the upper right portion of the abdominal cavity, tucked beneath the diaphragm and shielded by the lower ribs.
Shape, Size, and Color
The liver’s overall shape is roughly triangular when viewed from the front, wider on the right side and tapering to a thinner edge on the left. It spans most of the width of the upper abdomen, stretching about 15 centimeters (6 inches) across in most adults. The top surface is dome-shaped, molding itself against the curve of the diaphragm. The underside is more irregular, with indentations where it presses against the stomach, right kidney, and intestines.
In a healthy person, the liver’s color is a rich reddish-brown, similar to dark chocolate or raw beef liver you might see at a butcher counter. That deep color comes from the enormous volume of blood the organ holds at any given moment, roughly 13% of the body’s total blood supply. The surface is smooth and slightly shiny, covered by a thin, transparent layer of connective tissue called Glisson’s capsule. In a healthy liver, this capsule is only about 70 micrometers thick, far too thin to see with the naked eye, but it gives the organ a faintly glistening appearance.
The Four Lobes
The liver is divided into four lobes of very different sizes. The right lobe is the largest, making up the bulk of what you see when looking at the organ from the front. The left lobe is smaller and flatter, extending across the midline of the body toward the left side. Two much smaller lobes, the caudate and quadrate lobes, sit on the underside and are only visible when you flip the liver over. A band of tissue called the falciform ligament separates the right and left lobes on the front surface.
On the underside of the right lobe, there’s a small, pear-shaped sac nestled into a shallow depression. That’s the gallbladder, which stores bile produced by the liver. Also on the underside is a critical gateway called the porta hepatis, a slit-like opening where the major blood vessels and bile ducts enter and exit the organ. Two large vessels feed the liver here: the portal vein, which carries nutrient-rich blood from the digestive organs, and the hepatic artery, which delivers oxygen-rich blood from the heart.
What It Looks Like Up Close
Under a microscope, the liver’s internal structure is strikingly organized. The tissue is arranged into thousands of tiny hexagonal units called lobules, each roughly one to two millimeters across. Picture a honeycomb pattern: each hexagonal lobule has a small vein running through its center and blood vessel clusters at each of its six corners.
Blood flows inward from the corners toward the central vein through tiny channels called sinusoids, which are wider than normal capillaries and have porous walls. These porous walls allow the blood to make direct contact with the liver cells (hepatocytes) that line each lobule in neat rows, like spokes on a wheel. Scattered among the lining cells are specialized immune cells that filter bacteria and debris from the blood as it passes through. This architecture is what makes the liver so efficient at processing nutrients, filtering toxins, and producing bile simultaneously.
How Disease Changes the Liver’s Appearance
One of the most striking things about the liver is how dramatically its appearance changes with disease. A healthy liver and a diseased liver look nothing alike, and doctors can often identify the type and severity of liver disease just from its visual characteristics.
Fatty Liver
In fatty liver disease, the organ swells noticeably larger than normal, a condition called hepatomegaly. Its color shifts from reddish-brown to a pale yellow or tan, sometimes with a greasy sheen. This happens because fat droplets accumulate inside liver cells, literally changing the organ’s color from the inside out. On a microscopic level, tissue samples show fat globules stuffed into cells that would normally be clear. As the condition progresses to a more inflammatory stage, signs of swelling and early scarring start appearing in the tissue as well.
Cirrhosis
Cirrhosis transforms the liver’s smooth surface into something rough and lumpy. Scar tissue replaces healthy tissue, and the organ develops a surface covered in small bumps called nodules. These nodules vary in size depending on the cause of the cirrhosis. Alcohol-related cirrhosis tends to produce a finely bumpy surface with nodules smaller than 3 millimeters, giving it an almost grainy texture. Cirrhosis from chronic hepatitis C or autoimmune liver diseases typically creates larger nodules over 3 millimeters, producing an uneven, cobblestone-like surface sometimes described as a “jigsaw” pattern.
The color of a cirrhotic liver also changes, often becoming a duller tan or pale brown. The organ may shrink in advanced cases as functional tissue is replaced by dense scar tissue. Even the protective capsule thickens dramatically, roughly tripling from its normal 70 micrometers to over 230 micrometers in cirrhotic livers, and becomes packed with extra blood vessels and altered collagen fibers. Where a healthy liver feels soft and pliable to the touch, a cirrhotic liver feels firm and rubbery, sometimes almost rock-hard in advanced stages.
How It Compares to Other Organs
The liver stands out visually from its neighbors. It’s far larger than the kidneys (which weigh about 150 grams each) and denser than the lungs, which are spongy and pink. Unlike the heart, which is muscular and cone-shaped, the liver has no chambers or valves. Its texture is more uniform, similar to a dense, wet sponge. If you’ve ever seen liver sold as meat, that’s actually a close approximation of what the organ looks like fresh, though a living liver is slightly more vibrant in color due to active blood flow.
The liver also regenerates in a way no other solid organ can. If up to 75% of the liver is removed, the remaining tissue can regrow to nearly its original size within weeks. During this process, the regenerating liver looks slightly paler and softer than normal before gradually returning to its typical reddish-brown color and firm-but-pliable texture as new tissue matures.