The liver is the largest solid organ and the largest gland in the human body. It performs more than 500 essential tasks. Classified as part of the digestive system, the roles of the liver include detoxification, protein synthesis, and the production of chemicals that help digest food. This article covers the main roles of the liver, how the liver repairs itself, what happens when the liver isn’t working properly, and how to keep the liver healthy.
A few facts about the liver
The liver is classified as a gland.
This vital organ performs more than 500 functions in the human body.
It is the only organ that can regenerate.
The liver is the largest solid organ in the body.
Alcohol abuse is one of the leading causes of liver problems in the industrialized world.
Structure of the liver
The liver is one of the most versatile and important organs. Weighing between 1.44 and 1.66 kilograms, the liver is reddish brown with a rubbery texture. It is located above and to the left of the stomach and below the lungs. The skin is the only organ heavier and larger than the liver. The liver is roughly 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 Glisson’s capsule covers the outside of the liver. This capsule is also covered by the peritoneum, a membrane that forms the wall of the abdominal cavity.
This keeps the liver in place and protects it from physical damage.
Blood vessels
Unlike most organs, the liver has two main sources of blood. The portal vein carries nutrient-rich blood from the digestive system, and the hepatic artery carries oxygenated blood from the heart. Blood vessels divide into small capillaries, each ending in a lobule. The lobules are the functional units of the liver and are made up of millions of cells called hepatocytes. Blood is drained from the liver through three hepatic veins.
liver functions
The liver is classified as a gland and is associated with many functions. It’s hard to give a precise number, as the organ is still being explored, but the liver is believed to perform 500 distinct roles.
The main functions of the liver are:
Bile production: Bile helps the small intestine break down and absorb fats, cholesterol and certain vitamins. Bile is made up of bile salts, cholesterol, bilirubin, electrolytes and water.
Absorb and metabolize bilirubin: Bilirubin is formed by the breakdown of hemoglobin. Iron released from hemoglobin is stored in the liver or bone marrow and used to make the next generation of blood cells.
Promote the formation of blood clots: Vitamin K is necessary for the creation of certain coagulants which help to clot the blood. Bile is essential for vitamin K absorption and is created in the liver. If the liver does not produce enough bile, clotting factors cannot be produced.
Fat metabolism: Bile breaks down fats and makes them easier to digest.
Carbohydrate Metabolization: Carbohydrates are stored in the liver, where they are broken down into glucose and siphoned into the bloodstream to maintain normal glucose levels. They are stored as glycogen and released when a quick burst of energy is needed.
Storage of vitamins and minerals: The liver stores vitamins A, D, E, K and B12. It retains significant amounts of these vitamins. In some cases, it keeps several years of vitamins in reserve. The liver stores iron from hemoglobin in the form of ferritin, ready to make new red blood cells. The liver also stores and releases copper.
Helps Metabolize Protein: Bile helps break down protein for digestion.
Filters the blood: The liver filters and removes compounds from the body, including hormones, such as estrogen and aldosterone, and compounds from outside the body, including alcohol and other drugs .
Immunological function: The liver is part of the mononuclear phagocyte system. It contains a high number of Kupffer cells which are involved in immune activity. These cells destroy any pathogen that might enter the liver through the intestine.
Albumin production: Albumin is the most common protein in blood serum. It transports fatty acids and steroid hormones to help maintain proper pressure and prevent leaking blood vessels.
Synthesis of angiotensinogen: This hormone raises blood pressure by constricting blood vessels when alerted by the production of an enzyme called renin in the kidneys.
Regeneration
Due to the importance of the liver and its functions, evolution has ensured that it can regenerate quickly as long as it is kept healthy. This ability is found in all vertebrates, from fish to humans. The liver is the only visceral organ that can regenerate. It can fully regenerate, provided a minimum of 25% tissue remains. One of the most impressive aspects of this feat is that the liver can regain its previous size and capacity without any loss of function during the growth process.
In mice, if two-thirds of the liver is removed, the remaining liver tissue can return to its original size in 5 to 7 days. In humans, the process takes slightly longer, but regeneration can still occur in 8-15 days, an incredible achievement, given the size and complexity of the organ. Over the next few weeks, the new liver tissue becomes indistinguishable from the original tissue.
This regeneration is promoted by a number of compounds, including growth factors and cytokines. The most important compounds in the process appear to be:
hepatocyte growth factor
insulin
transforming growth factor-alpha
epidermal growth factor
interleukin 6
norepinephrine
The main liver diseases
There are a whole host of conditions that affect the liver. An organ as complex as the liver can experience a whole host of problems. A healthy liver works very efficiently. However, in the case of a diseased or malfunctioning liver, the consequences can be dangerous and even fatal.
Here are some examples of liver disease:
Fascioliasis: This disease is caused by the invasion of a parasitic worm called liver fluke, which can lie dormant in the liver for months or even years. Fascioliasis is considered a tropical disease.
Cirrhosis: Scar tissue replaces liver cells in a process known as fibrosis. This condition can be caused by a number of factors, including toxins, alcohol, and hepatitis. Eventually, fibrosis can lead to liver failure, as the functionality of liver cells is destroyed.
Hepatitis: Hepatitis is the name given to a general infection of the liver. It can be caused by viruses, toxins or an autoimmune response. It is characterized by inflammation of the liver. In many cases, the liver can heal itself, but liver failure can occur in severe cases.
Alcoholic liver disease: Drinking too much alcohol over long periods of time can cause liver damage. It is the most common cause of cirrhosis worldwide.
Primary sclerosing cholangitis (PSC): PSC is a serious inflammatory disease of the bile ducts that leads to their destruction. There is currently no cure, and the cause is currently unknown, although the disease is thought to be autoimmune.
Fatty liver disease: It usually occurs at the same time as obesity or alcohol abuse. In fatty liver disease, fat vacuoles build up in liver cells. If not caused by alcohol abuse, the disease is called non-alcoholic fatty liver disease.
It is usually caused by genetics, medications, or a diet high in fructose sugar. It is the most common liver disorder in developed countries and has been associated with insulin resistance. Non-alcoholic steatohepatitis (NASH) is a condition that can develop if NAFLD gets worse. NASH is a known cause of liver cirrhosis.
Gilbert’s syndrome: This is a genetic disease that affects 3 to 12% of the population. Bilirubin is not fully degraded. Mild jaundice may occur, but this disease 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 common cause of cancer death.
Liver health: how to take care of it
Below are some recommendations to help your liver work as it should:
Diet: Since the liver is responsible for digesting fat, consuming too much of it can overwork the organ and distract it from other tasks. Obesity is also linked to fatty liver disease.
Moderate alcohol consumption: Avoid having more than two drinks at a time. Excessive alcohol consumption eventually leads to cirrhosis of the liver. When the liver breaks down alcohol, it produces toxic chemicals, such as acetaldehyde and free radicals. For serious damage to occur, it takes the equivalent of a liter of wine a day for 20 years in men. For women, the threshold is less than half that amount.
Avoid illicit substances: Drugs can overload the liver with toxins.
Beware of drug mixtures: Some prescription drugs and natural remedies can interact negatively when mixed. Mixing drugs with alcohol puts a lot of pressure on the liver. For example, mixing alcohol and acetaminophen can lead to acute liver failure. Be sure to follow the directions on any medicine.
Airborne Chemical Protection: When painting or using strong cleaning or gardening chemicals, the area should be well ventilated or you should wear a mask. Airborne chemicals can cause liver damage because the liver must process any toxins that enter the body.
Travel and vaccinations: Vaccination is essential if you are traveling to an area where hepatitis A or B could be a problem. Malaria grows and multiplies in the liver, and yellow fever can lead to liver failure. Both of these diseases can be prevented with oral medications and vaccination.
Safer sex: There is no vaccine against hepatitis C. Caution should therefore be exercised with safer sex, tattoos and piercings.
Avoid exposure to blood and germs: Consult a doctor 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 ability to regenerate itself, the liver needs to be healthy to do so. The liver can be protected primarily through lifestyle choices and dietary measures.