It is one of the largest solid organs of the human body.
The skin is the only organ heavier and more significant than the liver.
The liver performs more than 500 essential tasks. Classified as part of the digestive system, liver functions include detoxification, protein synthesis, and the production of chemicals that help digest food.
Is the liver a gland or an organ?
The liver is one of the body’s vital organs, responsible for hundreds of chemical actions that the body needs to survive.
It is also a gland because it secretes chemicals used by other parts of the body. For these reasons, the liver is both an organ and a gland; it is the largest internal organ of the body.
With a weight between 3.17 and 3.66 pounds or between 1.44 and 1.66 kilograms (kg), the liver is reddish-brown with a gummy texture. It is located above and to the stomach’s left and below the lungs.
The liver is approximately triangular and consists of two lobes: a larger right lobe and a smaller left lobe. The lobes are separated by the falciform ligament, a band of tissue that keeps it anchored to the diaphragm.
A layer of fibrous tissue called a Glisson capsule covers the outside of the liver. This capsule is also covered by the peritoneum, a membrane that forms the abdominal cavity lining.
This helps keep the liver in place and protects it from physical damage.
Unlike most organs, the liver has two primary sources of blood. The portal vein brings blood rich in nutrients from the digestive system, and the hepatic artery carries oxygenated blood from the heart.
The blood vessels are divided into tiny capillaries, with each termination in a lobe. The lobes are the functional units of the liver and consist of millions of cells called hepatocytes.
The blood is eliminated from the liver through three hepatic veins.
The liver has multiple functions. It causes many of the chemicals required by the body to function normally, decomposes and detoxifies substances in the body, and acts as a storage unit.
It is difficult to give a precise number of functions since the organ is still being studied, but it is believed that the liver fulfills 500 different tasks.
The main functions of the liver include:
- Bile production: bile helps the small intestine break down and absorb fats, cholesterol, and some vitamins. Bile consists of bile salts, cholesterol, bilirubin, electrolytes, and water.
- Absorption and metabolism of bilirubin: Bilirubin is formed by the breakdown of hemoglobin. The iron released from hemoglobin is stored in the liver or bone marrow and is used to generate the next generation of blood cells.
- Support for blood clots: Vitamin K is necessary to create certain coagulants that help clot the blood. Bile is essential for the absorption of vitamin K and is made in the liver. If the liver does not produce enough bile, coagulation factors can not be created.
- The metabolization of fats: bile breaks down fats and makes them easier to digest.
- Metabolize carbohydrates: carbohydrates are stored in the liver, broken down into glucose, and diverted into the bloodstream to maintain normal glucose levels. They are stored as glycogen and released whenever a rapid burst of energy is needed.
- Storage of vitamins and minerals: the liver stores vitamins A, D, E, K, and B12. Saves significant amounts of these stored vitamins. In some cases, several years of vitamins are stored as backup.
- It helps metabolize proteins: bile helps break down proteins for digestion.
- It filters the blood: the liver filters and removes compounds from the body, including hormones, such as estrogen and aldosterone, and compounds from the outside of the body, such as alcohol and other drugs.
- Immunological function: the liver is part of the mononuclear system of phagocytes. It contains many Kupffer cells that are involved in immune activity. These cells destroy any disease-causing agent entering the liver through the intestine.
- Albumin production: albumin is the most common protein in blood serum. It carries fatty acids and steroid hormones to help maintain the correct pressure and prevent leakage of blood vessels.
- Synthesis of angiotensinogen: this hormone increases blood pressure by narrowing blood vessels when alerted by the production of an enzyme called renin in the kidneys.
The liver plays a vital role in the body’s detoxification by converting ammonia, a by-product of metabolism in the body, into urea that the kidneys excrete in the urine.
Because of the importance of the liver and its functions, evolution has ensured that it can grow back quickly as long as it stays healthy. This ability is seen in all vertebrates, from fish to humans.
The liver is the only visceral organ that can regenerate. It can be restored entirely, provided at least 25 percent of the tissue remains.
One of the most impressive aspects of this feat is that the liver can grow back to its previous size and capacity without losing function during the growth process.
In humans, the regeneration process can occur in 8 to 15 days, an incredible achievement, given the size and complexity of the organ. The new liver tissue becomes indistinguishable from the original tissue in the following weeks.
Liver regeneration is aided by compounds, including growth factors and cytokines. Some of the essential compounds in the process appear to be:
- Hepatocyte growth factor.
- Transforming growth factor-alpha.
- Epidermal growth factor.
An organ as complex as the liver can experience a variety of problems. A healthy liver works very efficiently. However, in a sick or malfunctioning liver, the consequences can be dangerous or even fatal.
Examples of liver disease include:
- Hepatic insufficiency: liver failure has many causes, such as infection, genetic diseases, and excess alcohol.
- Fascioliasis is caused by the parasitic invasion of a parasitic worm known as liver fluke, which can remain dormant in the liver for months or even years. Fascioliasis is considered a tropical disease.
- Cirrhosis: this causes scar tissue to replace the liver cells in a process known as fibrosis. This condition can be caused by several factors, such as toxins, alcohol, and hepatitis.
- Ascites: As cirrhosis occurs, the liver loses fluid (ascites) in the abdomen, which becomes distended and becomes heavy.
- Hepatitis: Hepatitis is given to general liver infection, and viruses, toxins, or an autoimmune response can cause it. An inflamed liver characterizes it. The liver can heal itself in many cases, but liver failure can occur in severe cases.
- Alcoholic liver disease: drinking too much alcohol for long periods can cause liver damage. It is the most common cause of cirrhosis in the world.
- Primary sclerosing cholangitis (PSC): PSC is a severe inflammatory disease of the bile ducts that causes its destruction. Currently, there is no cure, and the cause is currently unknown, although it is believed that the condition is autoimmune.
- Fatty liver disease: this usually occurs along with obesity or alcohol abuse. In fatty liver disease, vacuoles of fat accumulate in the cells of the liver.
- Gilbert’s syndrome: this is a genetic disorder that affects 3 to 12 percent of the population. Bilirubin is not completely decomposed. Mild jaundice may appear, but the condition is harmless.
- Liver cancer: the most common types of liver cancer are hepatocellular carcinoma and cholangiocarcinoma. The leading causes are alcohol and hepatitis. It is the sixth most common form of cancer and the second most frequent cause of cancer death.
- Gallstones: If a gallstone gets stuck in the bile duct that drains the liver, hepatitis and infection of the bile duct (cholangitis) can occur.
- Hemochromatosis: Hemochromatosis allows iron to be deposited in the liver and damage it. Iron is also deposited throughout the body, causing many other health problems.
- Primary sclerosing cholangitis: a rare disease with unknown causes, primary sclerosing cholangitis causes inflammation and scarring of the bile ducts in the liver.
Recommendations to preserve liver health
Here are some recommendations to help your liver continue to function as it should:
Diet: as the liver is responsible for digesting fats, consuming too many can overload the organ and alter it from other tasks. Obesity is also related to fatty liver disease.
Moderate alcohol intake: avoid consuming more than two drinks at a time. Drinking too much alcohol causes cirrhosis of the liver over time.
When the liver breaks down alcohol, it produces toxic chemicals, such as acetaldehyde and free radicals. For severe damage to occur, take the equivalent of one liter of wine every day for 20 years in men. For women, the threshold is less than half that.
Avoid illicit substances: when the last survey was conducted in 2012, about 24 million people in the United States had consumed an illegal and non-medical drug in the previous month. These can overload the liver with toxins.
Caution when mixing medications: some prescription drugs and natural remedies can interact negatively when combined. Mixing medications with alcohol puts significant pressure on the liver.
For example, alcohol and acetaminophen can cause acute liver failure. Be sure to follow the instructions for any medication.
Protection against chemicals in the air: When painting or using vigorous cleaning or gardening chemicals, the area should be well ventilated, or a mask should be worn. The chemicals in the air can cause liver damage because the liver has to process any toxins that enter the body.
Travel and vaccinations: Vaccination is essential if you travel to an area where hepatitis A or B could be a concern. Malaria grows and multiplies in the liver, and yellow fever can cause liver failure. Both diseases can be prevented with oral medication and vaccination.
Safe sex: there is no vaccine for hepatitis C, so caution is advised regarding safe sex, tattoos, and piercings.
Avoid blood and germs: get medical attention if you are exposed to someone else’s blood. It is also important not to share personal items related to hygiene, such as toothbrushes, and to avoid dirty needles.