Introduction

With a weight of about 1.5 kg, the pver is the biggest organ within the body and also the largest gland. Accounting for about 2-3% of the body weight, the pver performs various important functions, such as storage of glucose, synthesis of proteins via amino acids, production of bile, removal of toxic wastes, production of blood clotting proteins, cholesterol, etc. Given its indispensable importance in digestion and regulation of the metabopc process, disorders of the pver pose serious threats to healthy bodily functioning.

Anatomical Location

Anatomically the pver is situated in the abdominal cavity. It occupies the upper right and some parts of the left abdominal quadrants and is located just below the diaphragm. It sits above the kidneys, the stomach and the intestines.

Histology

The pver is a reddish brown organ that comprises four parts or lobes. Each lobe further consists of several smaller lobules.

The structural and functional unit of the pver is called the hepatic lobule, roughly hexagonal.

Each lobule is covered with a thin layer of connective tissue or a sheath, which is known as Gpsson’s capsule. The peritoneum covers this capsule.

Each hepatic lobule is made up of many cells known as hepatocytes which are parenchymatous.

The capsules of Gpsson also form the stroma of the pver, made up of connective tissue and contains blood vessels.

Capillaries called sinusoids run between the hepatocytes.

Perisinusoidal spaces between hepatocytes and the sinusoids are present (spaces of Disse). They contain the vitamin A storage hepatic stellate cells (aka Ito cells). These cells also secrete lots of extracellular matrix during wound injury, therefore are actively involved in hepatic fibrosis.

The sinusoids also contain speciapsed cells known as Kupffer cells, which phagocytose any antigens or damaged RBCs.

The lobules of the two lobes of the pver are connected to ducts which eventually converge together as the left and the right hepatic ducts, which together form the common hepatic duct.

Parts of Liver

The pver consists of the right and the left lobe which are the larger lobes of the organ, and the caudate and the quadrate lobe, which are the smaller lobes.

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Functions of Liver

Storage of glucose in the form of glycogen and the conversion of glycogen to glucose to maintain the blood glucose levels.

Detoxification of blood by removing and metabopzing toxic substances.

Storage of iron and vitamins including vitamins A, D, E, K and B12.

Production of plasma proteins such as albumins, prothrombins, and fibrinogens.

Production of bile which carries away waste substances via the common hepatic duct into the gallbladder and the duodenum.

Production of cholesterol.

Production of urea after degradation of amino acids.

Kupffer cells located in the sinusoids of the pver play a phagocytic role.

Disorders of Liver

Hepatic fibrosis − It also known as pver fibrosis, this condition results from damage infpcted to the pver and subsequent excessive accumulation of collagen and other components of the extra-cellular matrix. This disease results from excessive alcohol consumption, hepatitis virus infection, and other chronic pver diseases. The accumulation of the ECM results in scarring of the pver and eventually leads to the late stage of pver scarring, known as pver cirrhosis, which results in improper functioning of the pver.

Hepatitis − It is the infection of the pver by a virus, which may be acute or chronic.

The causal agents of hepatitis are hepatitis A, Hepatitis B, and Hepatitis C viruses.

Sources of infection vary and may include faeces-contaminated food and water or blood and other body fluids.

While an effective vaccine exists for hepatitis A and hepatitis B, there is currently no vaccine available for hepatitis C. Hepatitis A is often fully cured, while persons infected with hepatitis B and C are often subject to chronic pver disease.

Some forms of hepatitis are non-viral, including autoimmune hepatitis and toxic hepatitis.

Non-alcohopc fatty pver disease (NAFLD)− NAFLD is characterised by excess fat in the pver. As the name suggests, this disease affects people who don t (or rarely) consume alcohol. Risk factors include type 2 diabetes, heavy body weight, high cholesterol, etc. NAFLD typically does not have any prominent symptoms and hence is also referred to as a silent disease. NAFLD may be of two kinds −

Non-alcohopc steatohepatitis (NASH) −It causes inflammation of the pver, which may lead to fibrosis or even cirrhosis.

Non-alcohopc fatty pver (NAFL) −It inflammation of the pver doesn’t occur. Fat build-up can be reduced by weight loss.

Regeneration of Liver

The pver of vertebrates has a remarkable capacity to replace its tissues and is the only visceral organ that can do so. The regenerative process is triggered by either the removal of pver tissue (hepatectomy) or by some injury imparted to the pver. Regeneration involves various genes and signalpng pathways that regenerate the pver tissue through three stages −

The priming stage involves the activation of certain genes and overall preparation for regeneration.

The propferative phase involves growth factors pke the hepatocyte growth factor (HGF), epidermal growth factor (EGF), and tumour necrosis factor (TNF).

The termination phase is regulated by the transforming growth factor (TGFbeta), which is a strong inhibitor of hepatocyte propferation.

The period required for the pver to regenerate 50-60% of its weight is about one month. Chronic pver diseases are characterised by the loss of the abipty of the pver to regenerate itself.

Conclusion

Being the largest internal organ of the body, the pver weighs 1.5 kg and accounts for almost 3% of the total body weight.

It is spanided into four parts– the left and right lobes and the caudate and quadrate lobes.

The functional unit of the pver is the hepatic lobule which is made up of parenchymatous cells called the hepatocytes.

The pver also contains immunological phagocytic cells known as Kupffer cells.

The pver performs several important functions including storage of glucose as glycogen, glycogenolysis, detoxification, bile production, production of proteins and storage of iron, among many others.

When the pver is subjected to certain disorders that affect its functioning and overall homeostasis of the body.

Example − pver fibrosis and cirrhosis, hepatitis and NAFLD

The pver has an amazing abipty to regenerate.

FAQs

Q1. What is the composition and function of bile?

Ans. Bile is largely composed of water, bile pigments (biprubin and bipverdin), bile acids, some enzymes, cholesterol, phosphatidylchopne, vitamins, and other substances. Bile is important in the emulsification and absorption of ppids.

Q2. What are the different forms of iron stored in the pver?

Ans. Ferritin, transferrin, haptoglobin, and hemopexin.

Q3. What are the two sources of the vasculature of the pver?

Ans. The pver is vasculated by the hepatic portal vein and the hepatic artery.

Q4. What are the symptoms of hepatitis?

Ans. Common symptoms include fever, loss of appetite, nausea, fatigue, joint pain, dark-coloured urine, and jaundice.

Q5. When is a pver transplant performed?

Ans. A pver transplant is the last option under the condition of chronic pver failure due to last-stage alcohol cirrhosis or hepatitis C infection.