About Your Liver
The liver is one of the most vital and complex organs in the human body. It performs over 500 functions that are essential for life, such as metabolism, detoxification, blood filtration, bile production, digestion, and nutrient storage. The liver also plays a key role in the immune system, hormone regulation, blood clotting, and wound healing.
Where is the Liver and What does it Look Like?
The liver is located in the upper right quadrant of the abdomen, just below the diaphragm and behind the ribs. It is the largest solid organ in the body, weighing about 1.5 kg in adults. The liver has two main lobes, the right and the left, which are further divided into eight segments. Each segment has its own blood supply and bile duct. The liver is connected to the gallbladder, which stores and concentrates bile, and the hepatic portal vein, which brings blood from the digestive organs to the liver. The liver is also connected to the inferior vena cava, which carries blood from the lower body to the heart, and the hepatic artery, which brings oxygen-rich blood from the heart to the liver.
The liver is covered by a thin layer of connective tissue called the Glisson’s capsule, which protects and supports the liver. The liver is composed of millions of microscopic units called lobules, which are the functional units of the liver. Each lobule consists of rows of liver cells called hepatocytes, which are arranged around a central vein. The hepatocytes are responsible for most of the liver functions, such as producing bile, metabolizing nutrients, detoxifying toxins, and synthesizing proteins. Between the rows of hepatocytes, there are small blood vessels called sinusoids, which carry blood from the hepatic portal vein and the hepatic artery to the central vein. The sinusoids also contain specialized cells called Kupffer cells, which are part of the immune system and help remove bacteria, viruses, and foreign substances from the blood. The bile produced by the hepatocytes is collected by small ducts called canaliculi, which merge into larger ducts called bile ducts. The bile ducts join together to form the common hepatic duct, which carries bile to the gallbladder or the duodenum (the first part of the small intestine).
Anatomical Position of Your Liver
The liver, a critical organ in the human body, is strategically situated in the upper right quadrant of the abdomen, directly behind the diaphragm, protected by the rib cage and surrounded by essential digestive organs.
Right Upper Quadrant (RUQ):
The liver is mostly located in the right upper quadrant of the abdomen, but it also extends into the left upper quadrant.
Protection by the Rib Cage:
The rib cage shields the majority of the liver from external injury.
Relationship with neighboring organs:
- Stomach: It is located directly below the liver on the left side.
- Gallbladder: Located beneath the liver’s right lobe.
- Intestines: Situated beneath the liver and linked to its functions via bile production and release.
The liver is divided into two main lobes-the bigger right lobe and the smaller left lobe. These lobes are further divided into functional units to perform certain physiological activities.
Science Behind Liver Mechanism
Because of its intricate and dynamic operations, the liver is frequently referred to as the body’s “chemical processing plant”. Here’s an overview of the science underlying its mechanisms:
1. Blood Supply and Filtration
The liver has two blood supplies:
- The hepatic artery: delivers oxygen-rich blood from the heart.
- Portal vein: Transports nutrient-rich blood from the digestive tract.
When blood enters the liver, specialized cells known as hepatocytes filter and digest it. These cells eliminate contaminants, digest nutrients, and control critical biochemical pathways.
2. Metabolism of Nutrients
The liver plays an important function in metabolizing carbohydrates, proteins, and lipids.
Carbohydrate Metabolism:
The liver stores excess glucose as glycogen through a process known as glycogenesis. When energy is required, glycogen is broken down into glucose by glycogenolysis or generated from non-carbohydrate sources through gluconeogenesis.
Protein Metabolism:
The liver processes amino acids from dietary proteins. The liver makes essential proteins such as albumin and clotting factors. Furthermore, it eliminates ammonia (a consequence of protein breakdown) by converting it to urea, which is expelled in urine.
Fat Metabolism:
The liver converts fat into useful energy or stores it for later use. It also creates cholesterol and lipoproteins, which are necessary for hormone synthesis and cell membrane integrity.
3. Bile Production and Secretion
Bile, a yellowish-green fluid produced by hepatocytes, is necessary for digestion.
- Composition: Bile is composed of bile salts, cholesterol, and waste products such as bilirubin.
- Function: Bile acts as an emulsifier in the digestive tract, allowing lipids to be broken down and absorbed.
- Storage: Excess bile is held in the gallbladder and then discharged as needed.
4. Detoxification
The liver neutralizes toxic chemicals via two main pathways:
- Phase I Reactions: Enzymes like cytochrome P450 degrade poisons into less toxic molecules.
- Phase II Reactions: The liver further processes these chemicals by conjugating them with molecules such as glucuronic acid, which makes them water-soluble and excreted.
5. Regulation of Blood Components
The liver regulates the blood’s glucose, cholesterol, and amino acid levels.
It generates plasma proteins such as albumin, which assist regulate blood volume and pressure.
It also helps break down and recycle old or damaged red blood cells.
6. Hormone Metabolism
The liver is responsible for the metabolism and regulation of hormones such as insulin, thyroid hormones, and steroids. This ensures hormone balance and healthy body function.
Liver as an Energy Storage Hub
The liver serves as a storage facility for energy and critical nutrients:
- Glycogen: It is a stored form of glucose that can be converted back when energy levels decline.
- Fat-Soluble Vitamins: Vitamin A, D, E, and K are fat-soluble vitamins that are stored and released when needed.
- Iron and copper: These minerals are kept for metabolic purposes.
Cellular Composition of the Liver
The liver’s effectiveness comes from its specialized cells:
Hepatocytes:
They are the major cells in the liver responsible for metabolic, detoxifying, and storage functions.
Kupffer cells:
They are immunological cells that remove bacteria, old blood cells, and foreign particles from the bloodstream.
Stellate cells:
They store vitamin A and promote liver regeneration and repair.
Endothelial Cells:
These border the blood arteries and facilitate the flow of chemicals between the blood and liver cells.
The Liver’s Regenerative Capacity
The liver is exceptional in its ability to recover, even after extensive damage or partial surgical removal. When a portion of the liver is removed, the remaining tissue experiences compensatory hyperplasia, in which liver cells divide and increase to restore its original size and function.
Factors Influencing Regeneration
- Growth Factors: Proteins such as hepatocyte growth factor (HGF) promote liver cell development.
- Cellular Signals: Communication between hepatocytes and immune cells promotes controlled and effective regeneration.
This regeneration ability makes liver transplants and resections potential medical treatments for severe liver injury.
Fascinating Facts About the Liver
- The liver performs nearly 500 essential processes.
- It processes about 1.5 liters of blood every minute.
- It can lose up to 75% of its bulk while still regenerating completely.
- The liver produces approximately 800–1,000 milliliters of bile per day.
- Unlike other organs, the liver can regenerate following injury or partial removal.