The Liver Structure And Functions

The liver is an abdominal glandular organ in the digestive system. It is located in the right upper quadrant of the abdomen, under the diaphragm and on top of the stomach. The liver is a vital organ that supports nearly every other organ to some capacity.

The liver lies on the right side of the abdominal cavity beneath the diaphragm. Its main function is to process the contents of the blood to ensure composition remains the same. This process involves breaking down fats, producing urea, filtering harmful substances and maintaining a proper level of glucose in the blood.

Human liver structure

Liver is the organ with most secretes in our bodies. It is the hottest internal organs with incredible regenerative capacity. Sitting to the left of the belly, liver is the largest internal organ that supports almost every other organ in your body. It has a reddish-brown appearance and feels rubbery to the touch. This vital organ is responsible for hundreds of chemical reactions that are necessary for your

Location of Liver in Human Body

The chemical factory of your body, liver works tirelessly 24/7 and performs over 500 function vital to your life. As a gland, liver secretes bile which is emptied into the small intestine to facilitate digestion.

The liver is the body’s second-largest organ (skin is the largest organ), weighing about 1.4 kilograms. At any given moment, the liver holds about half a litre of blood, i.e. about 13 percent of the body’s blood supply.

The liver is shaped like a cone, and consists of two main lobes. Each lobe has eight segments that consist of 1,000 small lobes, or lobules. The lobules are connected to ducts that transport bile to the gallbladder and small intestine.

Human Liver structure

The Human Liver Size

Different factors, like age, gender and body size, affect the liver size. It is bigger in human males than that in females. The size of this gland is around 10.5 centimetres for men and about 7 centimetres for women. In the similar way, the liver weight is also different in different genders. Normal liver weighs about 1.2 to 1.5 kg in females and males, respectively.

A thin double-layered membrane makes a covering around it. This covering is called the peritoneum. It is this peritoneum which minimises friction of the liver against other organs.

Functions of the Human Liver

The liver has a complex role in the function of the body. This glandular structure, in the abdomen, has potential to perform over 500 different functions. All these functions are of vital importance for the body. The job of the organ ranges from acting as storehouse for different substances to making important secretions. Interestingly, the hepatic secretions are of both endocrine and exocrine nature.

However, the primary job is to purify the body from different harmful substances, for example, toxins.

On the other hand, as a gland, it secretes chemicals in the form of bile or liver juice. Bile contains salts that neutralise the acidic food coming from stomach. Meanwhile, the bile juice also helps in the digestion of fats.

In the presence of bile salts, the fatty substances break down into smaller, simpler pieces. Afterwards, these small particles move into the blood across the wall of small intestine.

Here follows a brief description of some of the major functions of the liver.

Liver as a Filter

The liver function requires it to serve as a filter between the blood that comes from the gut and the blood that circulates in the rest of the body. It clears the bacteria, antigens, damaged cells, proteins, hormones and drugs from the portal circulation.

From the variety of the functions of the liver, it becomes obvious that your body cannot afford any disorder of this organ. Its malfunctioning can have drastic effects on overall health of your body.

Processing Nutrients

Liver is the organ which receives almost all the nutrients that come from our digestive tract. However, chylomicrons are an exception, i.e. the liver does not process them. Chylomicrons are a type of complex lipids. These are mainly the lymph vessels that transport them across different parts of the body.

Liver processes all the nutrients present in the food we eat where the energy is stored. On the other hand, when necessary, it mobilises the stored energy for use throughout the body. So, in a sense, liver acts like an interface between the circulatory blood and the digestive system.

Blood Reservoir

The liver is a storehouse for large quantities of blood. When the total volume of the blood increases in the body, the liver quickly expands to store it. In other words, it can act like a blood reservoir.

In instances of cardiac failure, there is high pressure in the right atrium of the heart. Such a condition causes back pressure in the liver. This forces the liver to expand. The liver can then store about 500 to 1000 ml of extra blood within its own tissues.

The liver can also supply the body with this extra blood in times of low blood volume in the body.

The liver as a Blood Reservoir

Synthesis and Storage of Glycogen: The liver plays a key role in carbohydrate metabolism by converting glucose to glycogen. In this way, it prevents hyperglycaemia or high blood glucose after a meal rich in carbohydrate.

Conversion of Glycogen to Glucose: Liver converts the stored glycogen to glucose and releases it into the blood. This conversion occurs in response to low blood glucose level. So, your body can maintain a stable blood glucose level during fasting state and between meals.

Restoration of Glucose Level: When there is a decline in the blood glucose level, the stored sugar is converted into functional sugar.

Glucose from Non-Carbohydrate Compound: Sometimes, there are no glycogen reserves left in the body. In such a situation, liver comes to play its role. It can also convert non-carbohydrate compounds such as lactic acid, amino acid to glucose.

Unreasonably high output of hepatic glucose occurs in patients with diabetes mellitus. Consequently, there is disturbance in the functions of the liver. Certain antidiabetic drugs are useful to reduce hepatic glucose output.

Synthesis of Blood Clotting Factors & Other Plasma Proteins: Liver synthesises various plasma proteins. They include albumin, blood clotting factors, apolipoproteins, angiotensinogen and insulin, etc. The blood clotting factors are: fibrinogen, prothrombin, and factors v, vii, ix, x, etc. Liver replaces the plasma proteins in days to weeks after a major blood loss from the body in case of an accident.

Synthesis of Glycoproteins, Enzymes, etc.: Functions of the liver also include the synthesis of various important compounds in addition to plasma proteins. Synthesis and secretion of transferrin, globulins and other such compounds also falls under the domain of liver.

Detoxification of Poisons and Drugs: One of the functions of liver is to detoxify poisons and drugs. It involves the phase l and phase ll biotransformation reactions. If these poisons and drugs keep on circulating in the blood, they would harm and damage different delicate tissues and organs.

They can also have severe effects on the heart muscles. It will eventually lead to the malfunctioning of this vital organ. So, detoxification of drugs and poisons is an extremely important liver function.

Conversion of Ammonia to Urea: Liver removes ammonia from the blood by converting it to a less toxic compound, urea. Accumulation of ammonia and other toxins may eventually cause hepatic encephalopathy (confusion and coma).

In liver cirrhosis, there is an increase in the blood ammonia to toxic level. This occurs due to disturbance in liver function.

Lipid Metabolism: The liver function also includes the metabolism of lipids. It serves the job of:

· Formation of Ketone Bodies.
· Preservation of cholesterol homeostasis.
· Synthesis and secretion of very low density lipoproteins (VLDL).
· Clearance of High density lipoproteins (HDL), Low density lipoproteins (LDL) and chylo-micron remnants.

Alcohol Metabolism: Metabolising alcohol to acetaldehyde is another liver function. The excess amount of alcohol is directly toxic to the liver cells. The production of acetaldehyde occurs through the action of the enzyme alcohol dehydrogenase on alcohol.

Synthesis of Bile: As one of the functions of the liver, it plays a central role in the synthesis, secretion and metabolism of bile. Bile is a fluid that may vary in colour from dark green to yellowish brown. The gallbladder stores and concentrates the bile.

The bile contains bile salts, inorganic salts, fats and bilirubin. This hepatic secretion aids in the digestion and absorption of dietary fats across the wall of small intestine. It is also a major excretory route for lipid-soluble waste products.

· Storage of Vitamins and Iron: The uptake and storage of vitamins A, D, B12, folic acid and iron is also a liver function. The body uses these vitamins at the time of need.

· Storage of Minerals: Liver stores certain minerals such as iron and copper. Iron is an essential ingredient for blood production. Most of the body’s iron occurs as a part of haemoglobin and myoglobin. Here haemoglobin is an oxygen carrying protein while myoglobin is the oxygen-binding protein in muscle cells.

On the other hand, copper is a constituent of various proteins and metalloenzymes. In this capacity, the mineral plays an important role in the processes of development and proper growth. It is also useful for the maintenance of heart, brain, bone and other organs of the body.

· Destruction of Old RBCs: Your body should get rid of the old red blood cells that are of no use anymore. Liver performs the job of destroying the old RBCs. After that, it becomes easy for the body to remove them.

In short, the liver performs a great variety of tasks, ranging from the synthesis, storage and secretion to detoxification of harmful substances. Different secretions are of great metabolic importance. The liver function in digestion is also very significant.

Regenerative Capacity of Liver

Most cells in the liver are hepatocytes (around 60%). The remaining cell types are Kupffer cells, stellate cells, endothelial cellsand bile ductular cells.

When there is the loss of functional cells or hepatocytes, the growth factors and cytokines, etc. induce proliferation of the remaining liver cells.

This is the very reason that when you surgically remove some part of the liver or it suffers from some damage due to any other injury, the remaining hepatocytes can trigger liver regeneration. Thus, you can expect the complete recovery from the injury.

Signs of Liver Disease

Jaundice is the hallmark sign of liver disease. At the same time, it may be the most reliable marker of the severity of the condition. Typical symptoms of liver disease include:

· Icterus (jaundice)
· Fatigue
· Nausea
· Poor appetite
· Discomfort or pain in the right upper abdomen
· Intestinal bleeding
· Abdominal distention

Many patients may not have the above symptoms. But, the biochemical liver test will help confirm the disease.

Risk Factors for Liver Disease

As a part of special care of liver, you need to eliminate the risk factors for liver disease. Here follows a brief description of some of the common risk factors.

Alcohol Consumption: Alcohol is the leading cause of liver disease in many parts of the world. Next comes the turn of hepatitis C and B virus infection. More than two drinks per day in women and more than three drinks per day in men can increase the risk of alcoholic liver disease.

Recreational Drug Use: Everything that the nature has created has some benefits. But, its excessive and unwanted use can prove to be problematic. Smoking, recreational use of marijuana and snorting cocaine are potential risk factors for liver disease.

Hyperlipidemia: The levels of lipids and lipoproteins in the blood may get abnormally high. This is the condition of hyperlipidemia. Such a condition increases the possibility for liver to suffer from a disease.

Genetic Diseases: There are individuals who have a family history of cirrhosis, Wilson’s disease, hemochromatosis, diabetes or endocrine failure. This may also serve as a risk factor for the liver disease.

Viral Hepatitis: Intimate or occupational contact with individuals suffering from viral hepatitis can be the cause of hepatic disorders.

Exposure to Affected Blood: Accidental exposure to blood of a victim of liver disease will make you susceptible to the same condition.

Recent Surgery: Sometimes, after surgical operations, the process of healing may go bad. In turn, this will affect the functioning of liver. So, after recent surgery, take special care of this organ lest you should contact a painful liver disease.

Blood Transfusion: Blood transfusion is the process of putting new blood into the body of an individual. The reason for getting blood transfusion is the recipient’s body is unable to synthesise sufficient quality or quantity of the blood. On the other hand, such an act is likely to increase the risk of liver disease.

Sexual Contact: Sometimes, a healthy person makes sexual contact with patients of viral hepatitis. Consequently, they are very likely to get affected by the same abnormality.

Summing up, if you want to enjoy the perfect health, take good care of the liver. It has a lot of jobs (over 500) to perform in your body. Any liver disease would render it unable to accomplish the essential tasks.

Thus, there would be disturbance in many of your body’s mechanisms, putting your very survival at risk. You need to control the risk factors for liver disease.

Types of Liver Diseases

Jaundice

Jaundice is one of the common types of liver diseases that refers to the golden yellow appearance of skin and sclera. It results from too much accumulation of bilirubin in the body fluids. Jaundice is first noticeable in the sclera of the eyes. You call this yellow discoloration of the sclera as icterus. Jaundice is evident in skin when serum bilirubin level is 2.5 to 3 mg/dL.