LIVER
Introduction
Liver is the largest solid organ and the largest gland in the human body. Liver is reddish brown in color and shapes like a cone or wedge. It is located above the lungs in the right upper abdomen. It weighs about 3 to 3.5 pounds. It is the only organ that can regenerate. Liver is a unique organ because it has a dual blood supply from the portal vein and hepatic artery. Liver filters all blood supply in the body and breaks down poisonous substances such as alcohol, drugs. Liver produce bile, a fluid that helps digest fats and carry away the waste. Liver performs over 500 vital functions. These include removing waste products and foreign substances from the bloodstream, detoxification, protein synthesis, regulates blood clotting and regulating blood sugar level.
Structure
Liver is roughly triangular and consists of four lobes: a larger right lobe and a smaller left lobe and these two lobes are separated by the falciform ligament. The small caudate lobe extends from the posterior side of the right lobe and the small quadrate lobe is inferior to the caudate lobe. The liver's lobes can be further divided into eight segments, which are made up of thousands of lobules. Each of these lobules has a small duct that flows towards the common hepatic duct. These lobules are the functional unit of liver. It consists of millions of cells called hepatocytes. Layer of fibrous tissue is present that covers the outside of liver called Glisson's capsule. The falciform ligament runs inferiorly from the diaphragm, the wide coronary ligament connects the central superior portion of liver to the diaphragm and the right and left triangular ligaments connects the superior ends of the liver to the diaphragm. Liver has two major sources of blood that are
- hepatic artery
- hepatic portal vein
the main blood vessel that supplies the liver with oxygenated blood is the hepatic artery. Hepatic artery carry oxygenated blood from the heart. The blood vessel that carries blood from the GIT, pancreas, gallbladder and spleen to the liver.
Regeneration Of Liver
Liver is the only organ in the human body that has the capacity to regenerate. Liver can regenerate after surgical removal and injury. It can regenerate completely, as long as a minimum of 25 percent of the tissue remains. One of the important aspect is that the liver can regrow to its previous size and ability. If two-thirds of the liver is removed, the remaining liver tissue can regrow to its original size within 5 to 7 days. This regeneration is controlled and regulated by various factors such as growth factors and cytokines. Some of the important compounds are as following:
- insulin
- hepatocyte growth factor
- interleukin-6
- nor-epinephrine
- epidermal growth factor
- transforming growth factor
Embryonic Development
Liver development starts with formation and patterning of the endoderm. The ventral endoderm differentiates into thyroid, liver, pancreas and the dorsal endoderm differentiates into intestines and pancreas. The events which leads to differentiation of the ventral endoderm to the hepatoblasts then the liver bud then formed liver. The endoderm germ layer is established during maturation and forms a primitive gut. Embryonic liver originates from the ventral foregut endoderm. The first sign of embryonic development of liver is the formation of hepatic diverticulum. The anterior portion of hepatic diverticulum give rise to liver and intrahepatic biliary tree while the posterior portion forms the gallbladder and extrahepatic ducts. Hepatoblasts proliferate and penetrate the endoderm basement membrane to form the liver bud. The liver bud then expands in size, insert into the adjacent septum transversum mesenchyme. During the epithelial differentiation stage, hepatoblasts mature into hepatocytes and then differentiate into cholangiocytes.
Functions Of Liver
Liver is classed as a gland and associated with various functions. This organ is still being explored. More than 500 vital functions have been identified with the liver, usually in combination with other systems and organs. Liver also accounts for about 20 percent of resting total body oxygen consumption. Liver regulates most critical chemical levels in the blood and excretes a product called bile. This function that helps carry away the waste products from the liver. When the liver has broken down harmful substances, its by-products are excreted into the bile or blood. Blood by-products are filtered out through the kidneys and leave the body in the form of urine. Some of the more well-known functions of liver are as following:
- bile production
- fat mobilization
- regulating blood clotting
- filters blood
- regulates amino acids
- stores vitamins and minerals
- processes glucose
Diseases Related to Liver
If there will be disturbance in any organ it will lead to abnormality. Liver as we know is the organ of human body, it also shows abnormalities. There are more than 100 types of liver diseases. In a diseased or malfunctioning liver, the situation can be dangerous and even fatal. Some of the symptoms of liver problems are as following:
- jaundice
- nausea
- fatigue
- vomiting
- dark colored urine
- nose bleeds
- itchy nose
- weakness
- swelling of legs
- gynecomastia
some of the liver disease includes
- fascioliasis
- cirrhosis
- biliary atresia
- fatty liver disease
- hemochromatosis
- autoimmune hepatitis
- liver cancer
- alcoholic liver disease
Fascioliasis
Fascioliasis is a parasitic worm infection caused by common liver fluke Fasciola hepatica. The fluke that infect various parts of the body like blood vessels, GIT, lungs. This infection may be acute as well as chronic. In acute infection, immature flukes migrate through the intestinal wall, the peritoneal cavity, liver capsule and the parenchyma of liver before entering the biliary ducts where they mature in time of about 3 to 4 months. Symptoms in acute infection can cause
- nausea
- abdominal pain
- vomiting
- malaise
- eosinophilia
- weight loss
symptoms in chronic infection can cause
- obstructive jaundice
- pancreatitis
- asymptomatic
- abdominal pain
to diagnose fascioliasis, by
- antibody assays
- microscopic examination of stool
Cirrhosis
Cirrhosis is the last stage of the fibrosis of liver and caused by many forms of liver diseases such as hepatitis and chronic alcoholism. Cirrhosis is the impaired liver function caused by the formation of scar tissue known as fibrosis. The disease develops slowly over months or years. Cirrhosis often has no symptoms until liver is damaged but some symptoms that can cause cirrhosis are as following:
- fatigue
- loss of appetite
- weight loss
- itchy nose
- redness in the palms of the hand
- confusion
- drowsiness
to diagnose cirrhosis, following tests are performed
- laboratory tests
- biopsy
- imaging tests
Autoimmune Hepatitis
Autoimmune hepatitis is a chronic disease that occurs when your body's immune system turns against liver cells. Untreated autoimmune hepatitis can lead to cirrhosis and eventually to liver failure. Autoimmune hepatitis may be acute as well as chronic hepatitis. Signs of autoimmune hepatitis vary from person to person and some common symptoms of autoimmune hepatitis are as following
- abdominal discomfort
- fatigue
- skin rashes
- joint pain
- enlarged liver
- jaundice
to diagnose autoimmune hepatitis, following tests are performed:
Biliary Atresia
Biliary atresia is a disease of the bile ducts that affects only infants. Bile atresia may occur because the bile ducts did not form properly during pregnancy. In children, bile ducts may be damaged by the body's immune system in response to viral infection acquired after birth. Symptoms of disease typically appear with the first two weeks to two months of life. Symptoms that can cause biliary atresia are as following:
- dark urine
- white or clay colored stools
- weight loss
- irritability
to diagnose biliary atresia, following tests are performed:
- blood tests
- liver biopsy
- diagnostic surgery
- X-ray
- abdominal ultrasound
Hemochromatosis
Hemochromatosis is a disorder in which too much iron builds up in our body. Excess iron is stored in your organs, especially liver, heart and pancreas. Too much iron can lead to life threatening conditions, some of the symptoms of hemochromatosis are as
- joint pain
- abdominal pain
- fatigue
- diabetes
- loss of sex drive
- liver failure
- memory fog
- impotence
- weakness
to diagnose hemochromatosis, following tests are performed:
- blood tests
- liver function tests
- MRI
treatment of hemochromatosis include regularly removing blood from your body.
Recommendations
below are some recommendations to help keep your liver working as it should:
- diet
- avoid exposure to blood and germs
- moderate alcohol intake
- travel and vaccination
Amazing write-up!!
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