What is the liver?
The healthy human liver is a reddish-brown organ with a soft consistency and smooth, slightly reflective surface. Externally, it is surrounded by a firm connective tissue capsule. The average weight of the liver is 1.5 kilograms in women and 1.8 kilograms in men. Half of the weight is accounted for by the organ’s high blood content.
The four lobes of the liver
The organ is made up of two large and two small lobes. The two large lobes are called lobus dexter and lobus sinister (right and left liver lobes). The right lobe is significantly larger than left lobes.
On the underside of the two large lobes are the two small ones: square lobe (lobus quadratus) and caudate lobe (lobus caudatus). Between them is the hepatic orifice (see below).
Eight segments
Each segment consists of many lobules, one to two millimeters in size, which have a hexagonal shape. At the point where three lobules meet, there is a small zone of connective tissue. A small branch of the hepatic artery and portal vein are located there, as well as a small branch of the bile ducts. This zone is called the periportal field.
The lobules consist largely of liver cells (hepatocytes). These exhibit high metabolic activity and are primarily responsible for liver function.
Liver port
The hepatic portal (porta hepatis) is located on the underside of the large gland. Blood vessels enter the organ here, while the bile duct (ductus hepaticus) and lymphatic vessels and nerve fibers exit.
The supplying blood vessels are the portal vein (Vena portae) and the hepatic artery (Arteria hepatica). The latter supplies the organ with oxygen-rich blood. The portal vein, on the other hand, transports blood loaded with nutrients from the digestive tract.
Does the liver grow back?
What is the function of the liver?
The liver is the central metabolic organ and fulfills many vital tasks:
Nutrient Juggler
The intestine absorbs sugar, fatty acids, vitamins, etc. from the food pulp and sends them via the portal vein to the liver. The liver removes excess nutrients that are not currently needed in the body from the blood and stores them. If any region of the body (such as the brain) reports a need for certain nutrients, the storage organ releases them again and introduces them into the bloodstream.
Recycling and waste disposal
A wide variety of metabolic products are converted and broken down in the hepatocytes. The metabolic organ disposes of what is unusable either via the kidneys (water-soluble substances) or – packaged in the bile (see below) – via the intestines (fat-soluble substances).
High-performance filter
The hepatocytes filter out old hormones and blood cells, bacteria and defective cells from the blood. Pollutants such as ammonia (from protein breakdown), alcohol, pesticides and plasticizers, and drugs are also disposed of by the liver as a detoxification organ.
Hormone factory
Bile Mixer
Up to one liter of bile for fat digestion is mixed together daily in the liver and transported to the gallbladder or directly to the duodenum for storage.
Cholesterol supplier
Cholesterol is the starting material for important hormones and the bile acids as well as a building block of cell membranes. The body obtains a small part of the cholesterol it needs from food. It produces most of the rest itself, in the liver.
Body pharmacy
The liver provides clotting factors that ensure that a small cut does not lead to life-threatening blood loss (blood clotting).
High-performance machine
The following figures illustrate how efficiently the liver performs its tasks: every minute, 1.4 liters of blood flow through the organ. That makes about 2,000 liters of body juice per day, which is filtered, detoxified, freed of excess nutrients or loaded with needed nutrients by about 300 billion hepatocytes and released back into circulation.
Where is the liver located?
With its lower surface, the wedge-shaped organ adjoins various abdominal organs – the right kidney and adrenal gland, the duodenum, stomach and colon, the gallbladder, pancreas and spleen, and the small intestine.
The liver is fused to the underside of the diaphragm. It therefore shifts downward with each inhalation and can be palpated under the right costal arch even in a healthy person when inhaling deeply. On exhalation, the large gland is pulled up slightly with the diaphragm.
The metabolic organ is also attached to the abdominal wall by several ligaments and connected to the stomach and duodenum.
What problems can the liver cause?
The liver’s tasks are very diverse, which is why diseases or injuries to the organ often have very serious health consequences. Despite its high regenerative capacity, the large gland can be so severely damaged (for example, by alcohol, drugs or disease) that it can no longer perform its tasks (sufficiently).
In cirrhosis, the functional tissue of the gland is slowly and irrevocably replaced by connective tissue, which, however, is unable to fulfill the organ’s many tasks. Possible causes of cirrhosis include alcohol abuse, viral infections and hereditary metabolic diseases.
Doctors speak of a fatty liver when the fat content in the hepatocytes is excessively high. Possible causes include obesity, alcohol abuse and drug abuse.
Liver cancer (liver carcinoma) is a relatively rare cancer that mainly affects men. The malignant tumor usually originates from the hepatocytes (hepatocellular carcinoma), sometimes also from the bile ducts running in the organ (cholangiocellular carcinoma) or blood vessels (angiosarcoma).
Typical accompanying symptoms of the above-mentioned diseases can be fatigue and loss of performance, itching, pain under the right costal arch, nausea and vomiting, and impaired blood clotting and jaundice (icterus). The latter is caused by an increase in the bile pigmentbilirubin in the blood.
If the central metabolic organ can no longer perform its tasks, there is a danger to life. Such liver failure can occur acutely or develop chronically.
