Liver

Introduction to Liver

The liver is the largest gland in an animal or human body and viscera of the body. In the carnivorous, omnivorous, and herbivorous, different sizes of the liver can be observed, due to the difference of role in metabolism. The weight as per body weight is more in young animals, as it changes with age. In the fetal stage, the liver is derived from the endoderm epithelium on the ventral duodenum. The liver produces red and white blood cells during the fetal state. The main function of a liver is to produce bile and metabolism of protein, fat, and carbohydrates.

Liver in the Human Body

In humans, the liver is in the upper right corner of the body. It is situated just below the diaphragm and is tilted towards the body cavity. The right portion of the stomach is above the small intestine and the left portion is above the stomach.

Structure of Liver

In animals, the structure of the liver is similar to humans.

  • The liver is lined by the fibrous connective tissue. This capsule is called Glisson’s capsule. In animals, the liver is also considered to be derivative from the epithelial tissue. 

  • The cellular structure of the liver is simple and it consists of the repetition of a simple structure called lobule. 

  • The hepatocyte cells are organized in the anastomosed layer. These layers of hepatocytes are much thicker and fuse together to form a complex structure.

  • Endocrine secretion of a large number of plasma proteins like lipoprotein and albumin is done by hepatocytes.

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Liver Anatomy

The anatomy of the liver is as follows

  • The liver is divided into certain lobes namely left lateral lobe, left medial lobe, and right lateral lobe, right medial lobe, quadrate, caudate, and papillary.

  • Each lobe is further divided into eight segments and all of the segments contain 1000 lobules.

  • Each of the lobules in the segment has a small tube. A tube from each lobule joins to make the common hepatic duct.

  • The function of the hepatic duct is to transport bile made by the liver cells to gallbladder and duodenum.

  • Blood is supplied to the liver from two distinct sources; those are oxygenated blood flow from the hepatic artery and nutrient-rich blood flow from the hepatic portal vein.  

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Liver Position in the Body

In the majority of the animals, the liver is found underneath the diaphragm. Most of the blood which reaches the liver comes from the portal vein and due to heavy blood supply, the liver has a reddish color.

The Function of the Liver in the Human Body

The liver performs several activities in the human body.

Some of the major functions of the liver are mentioned below:

  • The liver helps to regulate the blood chemical levels.

  • The liver produces bile, which helps to remove the waste product away and bile helps in the breakdown of fat in the small intestine.

  • The liver produces blood plasma proteins like albumin.

  • Glycogenesis, the process of storing excess glucose in the form of glycogen, occurs in the liver. 

  • The liver converts poisonous ammonia to urea which can be excreted by the urine. Urea is the end product of protein metabolism.

Role of Liver

The liver performs the filtration of blood which comes out from the digestive tract. In this process the liver also detoxifies the blood. The absorption of drugs in our body also occurs in this particular process. The liver secretes bile which is a very important aspect of fat metabolism. The liver makes protein for blood. Blood proteins are important as they help in the clotting of the blood as without the presence of blood proteins minor wounds could be fatal due to immense blood loss.

Digestive Function of the Liver

The liver makes bile juice which helps in the digestion process and also helps to carry out the waste materials. Liver stores the glucose and releases it as per the requirement of the body through the process of glycogenolysis. In glycogenolysis, glycogen breaks down to form glucose. The liver also helps to clear bilirubin. The liver produces cholesterol and protein to carry fat through the body. 

Diseases of Liver

  • Jaundice - When bilirubin gets stored in our body in an excess amount, then a yellow tint on the eye and skin is observed. This is known as jaundice. This disease is caused due to inflammation of the liver.

  • Liver Cancer – If cirrhosis is present in the liver, then it may lead to liver cancer and the most common type of liver cancer is Hepatocellular Carcinoma.

  • Hepatitis – This is caused by the viruses Hepatitis A, B, C, due to the inflammation of the liver.

FAQ (Frequently Asked Questions)

1. What is Causing a Drastic Increase in Liver Cancer Cases?

According to the research Hepatitis C, diabetes along with obesity causes an increase in liver cancer cases. Obesity and metabolic syndrome are characterized by abdominal obesity, diabetes, high blood pressure, or cholesterol. These are the risk factors for liver cancer. Excess consumption of alcohol leads to liver cirrhosis and it also causes liver cancer and in non-alcoholic people, metabolic syndrome may lead to ‘Steatohepatitis’. It is the deposition of fat in the liver and it also causes liver cancer. To date, no therapeutic interventions have been established to lower the risk of this disease as it has been observed recently.

2. What Causes the Liver to Die?

There are various reasons for liver failure. Some of the important reasons are stated below.

  • Drug overdoses – Drug overdoses may cause liver cells to die like large doses of Acetaminophen can cause liver failure.

  • Virus infection – Infection caused by viruses like Hepatitis A, B, and E which is known as ‘Cytomegalovirus’ or  CMV may also lead to liver failure.

  • Industrial toxins – Many of the industrial toxins like Carbon tetrachloride(CCl4) may lead to liver failure.

  • Autoimmune hepatitis – In this type of autoimmune disease, the immune system of our body attacks the liver and causes liver failure.