The liver is the largest stable organ in the human body, and the largest gland. It does more than 500 essential tasks.
Classified as part of the digestive system, the liver’s functions include detoxification, synthesis of proteins and the production of chemicals that help digest food.
In article, we cover the key functions of the liver, how the liver regenerates, what happens when the liver does not function properly and how the liver is kept healthy.
Important facts about the liver
- The liver is classed as a gland.
- This vital organ carries out more than 500 roles 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 major causes of liver problems in the industrialized world.
Structure
The liver is reddish-brown with a rubbery texture and weighs between 3.17 and 3.66 pounds (lb), or between 1.44 and 1.66 kilograms (kg). It is situated above and below the lungs and to the left of the stomach.
Heavier and larger than the liver, the skin is the only organ.
The liver is approximately triangular and has two lobes: a larger lobe on the right and a smaller lobe on the left. The lobes are separated from each other by the falciform ligament, a tissue band that keeps it anchored to the diaphragm.
The outside of the liver is covered by a layer of fibrous tissue called the Glisson capsule. The peritoneum, a membrane that forms the lining of the abdominal cavity, also covers the capsule.
This helps to hold the liver in place and protects it against physical harm.
Blood vessels
Unlike other organs, two main sources of blood are in the liver. The portal vein takes nutrient-rich blood from the digestive system and carries oxygenated blood from the heart through the hepatic artery.
The blood vessels divide into tiny capillaries, resulting in a lobule at each. Lobules are the liver’s functional components, which consists of millions of cells called hepatocytes.
Blood is removed via three hepatic veins from the liver.
Functions
The liver is known as a gland and has many functions to it. Giving a precise number is difficult, as the organ is still being explored, but it is thought that the liver performs 500 distinct roles.
The major 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.
- Absorbing and metabolizing bilirubin: Bilirubin is formed by the breakdown of hemoglobin. The iron released from hemoglobin is stored in the liver or bone marrow and used to make the next generation of blood cells.
- Supporting blood clots: Vitamin K is necessary for the creation of certain coagulants that help 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 metabolization: Bile breaks down fats and makes them easier to digest.
- Metabolizing carbohydrates: 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 whenever a quick burst of energy is needed.
- Vitamin and mineral storage: The liver stores vitamins A, D, E, K, and B12. It keeps significant amounts of these vitamins stored. In some cases, several years’ worth of vitamins is held as a backup. 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 proteins: Bile helps break down proteins 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 high numbers of Kupffer cells that are involved in immune activity. These cells destroy any disease-causing agents that might enter the liver through the gut.
- Production of albumin: Albumin is the most common protein in blood serum. It transports fatty acids and steroid hormones to help maintain the correct pressure and prevent the leaking of blood vessels.
- Synthesis of angiotensinogen: This hormone raises blood pressure by narrowing the blood vessels when alerted by production of an enzyme called renin in the kidneys.
Regeneration
Evolution has ensured that due to the importance of the liver and its functions, it can regrow rapidly as long as it is kept healthy. The ability is seen from fish to humans in all vertebrates.
The liver is the only visceral organ which is able to regenerate.
It can fully regenerate as long as the tissue remains at least 25 percent. One of the most impressive aspects of this feat is that, during the growth process, the liver can regrow to its previous size and ability without any loss of function.
In mice, if two thirds of the liver is removed, the remaining liver tissue may regrow within 5 to 7 days to its original size. In humans the process takes a little longer, but regeneration can still occur in 8 to 15 days – an incredible accomplishment considering the organ’s size and complexity.
The new liver tissue will become indistinguishable from the original tissue in next few weeks.
A number of compounds, including growth factors and cytokines, aid this regeneration. Some of the most significant compounds appear to be in the process:
- hepatocyte growth factor
- insulin
- transforming growth factor-alpha
- epidermal growth factor
- interleukin-6
- norepinephrine
Diseases
An organ as complex as the liver may encounter a range of problems. A healthy liver performs very well. However, the effects can be dangerous or even fatal in a diseased or dysfunctioning liver.
Examples of liver disease include:
Fascioliasis: This is caused by the parasitic invasion of a parasitic worm known as a liver fluke, which for months or even years may lie dormant in the liver. Fascioliasis is regarded as a tropical disease.
Cirrhosis: In a process known as fibrosis, scar tissue destroys liver cells. There are a number of factors that can cause this condition, including toxins, alcohol and hepatitis. Fibrosis will ultimately result in liver failure as the functionality of the liver cells is destroyed.
Hepatitis: Hepatitis is the name given to a general liver infection, and it can be caused by viruses, toxins or an autoimmune reaction. It contains an inflamed liver. The liver can heal itself in many cases but in severe cases, liver failure can occur.
Alcoholic liver disease: Drinking too much alcohol can cause liver damage over long periods of time. It is the world’s most common Cirrhosis Cause.
Primary sclerosing cholangitis (PSC): PSC is a serious inflammatory disease that results in the destruction of the bile ducts. There is no cure at the moment, and the cause is currently unknown, though the condition is believed to be autoimmune.
Fatty liver disease: This usually happens in conjunction with obesity or alcohol abuse. In fatty liver disease fat vacuoles build up in the cells of the liver. If it is not caused by alcohol abuse, the condition is called non-alcoholic fatty liver disease (NAFLD).
It is usually caused by a diet high in fructose sugar, genetics, medications or. It has been associated with insulin resistance and is the most common liver disease in developing countries. If NAFLD gets worse, non-alcoholic steatohepatitis (NASH) is a condition that may develop. NASH is a known cause of liver cirrhosis.
Gilbert ‘s syndrome: This is a genetic condition affecting 3 to 12 percent of the population. Bilirubin isn’t completely decomposed. There may be slight jaundice but the condition is harmless.
Liver cancer: Hepatocellular carcinoma and cholangiocarcinoma are among the most common types of liver cancer. Alcohol and hepatitis are significant causes. It is the sixth most common cancer form, and the second most common cause of cancer death.
Health
Below are some recommendations to help keep your liver working as it should:
- Diet: As the liver is responsible for digesting fats, consuming too many can overwork the organ and disturb it from other tasks. Obesity is also linked 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, it takes the equivalent of a liter of wine every day for 20 years in men. For women, the threshold is less than half of that.
- Avoiding illicit substances: When last surveyed in 2012, close to 24 million people in the United States had consumed an illicit, non-medical drug within 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, combining alcohol and acetaminophen can lead to acute liver failure. Be sure to follow the instructions on any medications.
- Protection against airborne chemicals: When painting or using strong cleaning or gardening chemicals, the area should be well ventilated, or a mask should be worn. Airborne chemicals can cause liver damage because the liver has to process any toxins that enter the body.
- Travel and vaccinations: Vaccination is essential if you are traveling to an area in which hepatitis A or B might be a concern. Malaria grows and multiplies in the liver, and yellow fever can lead to liver failure. Both diseases can be prevented by oral medication and vaccination.
- Safe sex: There is no vaccination for hepatitis C, so caution is advised in regards to safe sex, tattoos, and piercings.
- Avoid exposure to blood and germs: Receive medical attention if you are exposed to the blood of another person. 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, it is up to the liver to be able to do so. Lifestyle choices and dietary measures can mostly protect the liver.Despite its ability to regenerate, the liver depends on being healthy to do so. The liver can mostly be protected through lifestyle choices and dietary measures.
