It is one of the largest solid organs of the human body.
The skin is the only organ heavier and bigger 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 vital organs of the body, responsible for hundreds of chemical actions that the body needs to survive.
It is also a gland because it secretes chemicals that are used by other parts of the body. For these reasons, the liver is both an organ and a gland; In fact, 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 left of the stomach 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 lining of the abdominal cavity.
This helps keep the liver in place and protects it from physical damage.
Unlike most organs, the liver has two main 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 small 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 also 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 functions.
The main functions of the liver include:
- Production of bile: bile helps the small intestine to 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 for the creation of certain coagulants that help to coagulate the blood. Bile is essential for the absorption of vitamin K and is created in the liver. If the liver does not produce enough bile, coagulation factors can not be produced.
- Metabolization of fats: bile breaks down fats and makes them easier to digest.
- Metabolize carbohydrates: carbohydrates are stored in the liver, where they are 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 a large number of Kupffer cells that are involved in immune activity. These cells destroy any disease-causing agent that can enter 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 an important role in the detoxification of the body 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 completely regenerated, provided that 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 any loss of 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. In the following weeks, the new liver tissue becomes indistinguishable from the original tissue.
Liver regeneration is aided by a series of compounds, including growth factors and cytokines. Some of the most important 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 liver that is sick or malfunctioning, 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: This 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 cells of the liver in a process known as fibrosis. This condition can be caused by a number of 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 the name given to a general infection of the liver, and viruses, toxins or an autoimmune response can cause it. It is characterized by an inflamed liver. In many cases, the liver can heal itself, but liver failure can occur in severe cases.
- Alcoholic liver disease: drinking too much alcohol for long periods of time can cause liver damage. It is the most common cause of cirrhosis in the world.
- Primary sclerosing cholangitis (PSC): PSC is a serious 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 disorder is harmless.
- Liver cancer: the most common types of liver cancer are hepatocellular carcinoma and cholangiocarcinoma. The main 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 an 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 serious 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 illicit and non-medical drug in the last month. These can overload the liver with toxins.
Caution when mixing medications: some prescription drugs and natural remedies can interact negatively when mixed. Mixing drugs with alcohol puts significant pressure on the liver.
For example, the combination of 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 strong 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 exposure to 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.
Despite its regenerative capacity, the liver depends on being healthy to do so. The liver can be protected primarily through lifestyle choices and dietary measures.