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
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| 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.
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| 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.
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| 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 cells
and 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.
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| Jaundice – one side grows yellow |
Causes of Jaundice
•
Overproduction of bilirubin.
•
Less hepatic uptake of bilirubin
•
Impaired conjugation of bilirubin
•
Defective hepatocellular excretion of bilirubin
Symptoms of Jaundice
•
The most significant symptom is the yellowing of the
skin and the sclera, the white part of your eyes.
•
Abdominal pain which is characteristic of the blockage
in the bile duct.
•
Other symptoms include fever, fatigue, vomiting and
the weight loss, etc.
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