The liver is the largest internal organ in the body, and like most other organs, it performs more than one function. It produces bile, a substance needed to digest and absorb fats; filters the blood to keep the body clear of toxins and harmful substances; and is responsible for a number of metabolic processes, most of which are necessary to life and not done elsewhere in the body. The liver has a large amount of redundancy and uses only a small amount of its full potential at any one time. Unfortunately, this means that diseases that affect the liver can be well-entrenched and not show clinical symptoms until much later. The liver does have an advantage, though: liver cells can regenerate themselves. In some cases, this regenerative ability allows a diseased liver to return to normal function. Very few organs in the body have this ability.
The normal liver is a deep red color with a firm consistency. It is divided into six lobes, with each lobe being made up of lobules. Each lobule is composed of numerous blood-filled cavities known as sinusoids. These sinusoids give the liver a spongy texture and enable it to hold large amounts of blood. The liver is located in the front of the abdominal cavity, lying directly behind the diaphragm and directly in front of the stomach. It is positioned horizontally across the front of the abdomen.
Unlike other organs, the liver is supplied with nutrients from two major blood vessels: the hepatic artery and the portal vein. The hepatic artery carries oxygen-rich blood from the heart and lungs, while the portal vein originates from the digestive tract. The hepatic artery supplies most of the oxygen and nutrients the liver cells use during metabolism and about 1/3 of the blood that flows into the liver. The portal vein supplies the other 2/3 of the blood that flows into the liver. This vessel takes food that is absorbed from the intestines directly to the liver. Crucially, this exposes the liver to ingested toxins and bacteria, which the liver detoxifies before this blood enters the general circulation. This detoxification process protects the other organs from bacteria and toxins that could injure them.
So, what exactly are some the numerous functions of the liver?
The production of bile, a greenish-yellow fluid which consists of bile acids and waste products such as bilirubin. This is released into the gastrointestinal tract to help break down fats in the small intestine during digestion. The liver makes bile continuously, even when food is not being digested. The extra bile is stored in the gallbladder.
The conversion of ammonia in the blood to urea. Bacteria in the intestinal tract produce ammonia as they break down proteins. This ammonia can accumulate in the blood at potentially toxic levels. Urea is passed out of the body in the urine.
Stores the fat-soluble vitamins A, D, E and K, which need bile in order to be absorbed by the body.
The production of cholesterol and special proteins (called lipoproteins) that help carry fats through the body.
The regulation of blood levels of amino acids, which form the building blocks of proteins.
The conversion and storage of excess glucose (sugar) into a compound called glycogen. Glycogen can later be converted back to glucose for energy whenever the body’s glucose levels fall below normal.
The production of certain proteins that circulate in the blood, such as albumin.
The production of factors responsible for blood clotting.
Destroys old red blood cells.
Stores iron that is used in the processing of hemoglobin, which is essential for carrying oxygen in the blood.
Breaks down hemoglobin, creating metabolites that are added to bile as pigment (bilirubin).
Some storage of blood that can be shunted immediately into the general circulation when needed after injury or sudden blood loss.
Clearing the blood of foreign substances, such as toxins, medications, and anesthetic agents.
Several hundred other minor but vital functions.
As we can see, the liver is an amazing organ that is vital for life! Thank you, you wonderful liver! =^_^=
Next month, we’ll talk more about organs. Until then, please enjoy the wonderful colors of autumn with your furry friends!