The Liver and Its Functions

What Is the Liver?

The liver is the largest internal organ in the human body. It is situated in the upper right abdomen, beneath the diaphragm. It has a unique structure formed of two main lobes combined with many smaller units called lobules. The liver carries out various important functions that include digestion, metabolism, detoxification, and storage of nutrients.

Key Facts About the Liver

Some of the key facts about liver are:

• The liver filters all of the blood in the body.

• Breaks down poisonous substances, such as alcohol and drugs.

• The liver also produces bile that helps digest fats and carry away waste.

• The liver consists of four lobes, which are each made up of eight sections and thousands of lobules (or small lobes).

Location and Position of the Liver

The liver is one of the most vital organs in terms of human physiology, credited with maintaining different crucial activities that help keep a person's health in good condition.

• The liver is located in the upper right quadrant of the abdominal cavity.

• Located under the diaphragm, majorly situated on the right side.

• It extends across the midline to the left side.

• It lies at the junction of the blood supply from both the hepatic artery and portal vein.

• It is anatomically well-placed for its metabolic and detoxification functions.

Structure and Anatomy of the Liver

The liver is anatomically well-placed for its metabolic and detoxification functions. The structure and anatomy of the liver is discussed below:

Lobes of the Liver

• The liver is divided into four lobes—right, left, caudate, and quadrate.

• All the four lobes have different functions and different blood supply.

Lobes

• These lobes essentially contain a tissue composed of hepatocytes, each lobule is hexagonal in shape.

• These are the main functional cells of the liver grouped into lobules.

• They are arranged around a central vein.

Blood Supply

• The hepatic artery delivers oxygen-rich blood

• The portal vein delivers nutrient-rich blood from the gastrointestinal tract—to accomplish metabolic processes in the liver.

Histology of Liver

Under the microscope, the tissue of the liver consists of hepatocytes organised into hexagonal lobules.

• These project from a central vein, which is at the centre of each lobule.

• The hepatocytes are also surrounded by sinusoids and specialised capillaries.

• Blood from the hepatic artery and portal vein flows into the sinusoids.

• The liver also lodges the Kupffer cells, which are specialised macrophages that form an integral part of the immune function of the liver and its detoxification ability.

Functions of the Liver

It is one of the most vital organs performing a wide range of crucial functions related to the maintenance of overall health. The functions of the liver can be broadly categorised into metabolic processes and detoxification.

Metabolic Functions

• Protein metabolism: It synthesises important proteins like albumin, which helps in maintaining blood volume, and clotting factors necessary for blood coagulation.

• Carbohydrate metabolism: It stores glucose in the form of glycogen and releases it in amounts needed to maintain blood sugar.

• Lipid metabolism: The liver is a significant organ for regulating cholesterol synthesis and degradation. It plays a critical role in lipid metabolism.

Detoxification

Biotransformations by the liver change drugs and other toxins into forms readily excreted by the body.

Bile production

The liver produces bile, which contains bile salts which aids the digestion of fats and removes waste products from the body.

Liver Diseases

Liver diseases are a group of disorders characterised by damage to liver structures and functions. These can be caused by various factors, either viral diseases or chronic diseases, and may require special treatment management and care. These include the following:

Hepatitis

• Type A, B and C occur due to viral infection and result in inflammation.

• Symptoms: Jaundice, fatigue and abdominal discomfort.

• Treatments: Antiviral medications and supportive care.

Liver Cirrhosis

• Causes: Prolonged alcohol abuse, chronic viral hepatitis, and other causes which end up with irreversible scarring

• Symptoms: Ascites and Hepatic encephalopathy.

• Management: Lifestyle modifications, sometimes Liver transplantation.

Liver Cancer (Hepatocellular Carcinoma)

• Causes: Underlying liver disease, such as cirrhosis or chronic hepatitis.

• Diagnosis: Done by CT, MRI, and biopsy.

• Treatment: Surgery to chemotherapy, depending on the stages.

Liver NEET MCQs (With Answers & Explanations)

Important questions asked in NEET from this topic are:

• Structure and anatomy of the liver

• Functions of the liver

• Disorders related to liver

Practice Questions for NEET

Q1. The toxic substances in the diet are detoxified in the human body by

1. Liver

2. Lungs

3. Kidney

4. Stomach

Correct answer: 1) Liver

Explanation:

Toxic chemicals in the human body must be detoxified by the liver. It removes waste materials, medications, and dangerous compounds from the blood. These compounds are broken down by the liver's enzymes, which facilitate the body's removal of them through bile or urine. The primary function of the lungs is the exchange of gases, specifically carbon dioxide and oxygen, rather than the detoxification of chemicals. The kidney's primary function is not to directly detoxify poisons; rather, it filters waste materials from the blood to create urine. Although it aids in digesting, the stomach is not a key player in detoxification.

Hence, the correct answer is option 1) Liver.

Q2. Among the following options, what is the primary storage form of carbohydrates in mammals, and where is it predominantly stored?

1. Lactic acid in Cardiac muscles

2. Glycogen in Liver and Skeletal muscles

3. Glucose in Liver and Adipose tissue

4. Glycogen in Liver and Spleen

Correct answer: 2) Glycogen in Liver and Skeletal muscles

Explanation:

Glycogen in the liver and skeletal muscles is the correct answer. In mammals, glycogen serves as the primary storage form of carbohydrates. It is predominantly stored in the liver and skeletal muscles. Glycogen acts as a glucose reserve that can be broken down when energy demands increase.

Hence, the correct answer is option 2) Glycogen in Liver and Skeletal muscles.

Q3. Liver is the largest gland and is associated with functions, choose one which is not correct

1. Metabolism of carbohydrate

2. Digestion of fat

3. Formation of bile

4. Secretion of hormone called gastrin

Correct answer: 4) Secretion of hormone called gastrin

Explanation:

The liver plays a crucial role in various physiological processes, including the secretion of a hormone known as gastrin. This hormone is responsible for stimulating the production of gastric acid in the stomach, aiding in digestion. In addition to this important function, the liver also performs a multitude of other vital tasks that are essential for maintaining overall bodily health and homeostasis secretion of a hormone called gastrin; as the liver performs all the other functions specified herein.

Hence, the correct answer is option 4) Secretion of a hormone called gastrin.

Also Read:

• MCQs on Histology of the Liver

• Pancreas Function in Human Body

• Digestion in Ruminants

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