The liver is an organ located just below the diaphragm in humans and is made up of four lobes. The left lobe, right lobe, quadrate lobe and caudate lobe make up the structure of the liver. Each of the lobes of the liver consist of liver lobules, which contain many millions of hepatic cells, the specialized cell of the liver.
Features
The liver itself is supplied with oxygen by the hepatic artery, which branches off of the aorta. The hepatic artery branches off into capillaries to move oxygen-rich blood to the entirety of the liver, which allows the organ to function properly. The BBC Science and Nature website states that the hepatic cells of the liver engage in more chemical processes than any other cells in the body.
Function
The liver is one of the most versatile organs in the body. The textbook "Microbiology: 6th Edition" recognizes many important functions of the liver. The liver is involved in both the production of amino acids, and the conversion between amino acids and other molecules. The liver also stores excess glucose that it doesn't release into the blood as glycogen. When the body is low on fatty acids, the preferred energy source of the brain, it relies on ketone bodies for energy. Ketone bodies are produced in the liver as a byproduct of fatty acid degradation. They can be an especially important energy source to provide energy to the brain in the absence of a food source.
Blood arrives at the liver from the stomach and small intestines. This blood is full of nutrients and minerals from the food that is processed by the hepatic cells of the liver.
Cholesterol, generally seen as a molecule of concern to the human body, is actually extremely important for human cells. Cholesterol integrates into the plasma membrane of cells and helps to stabilize cells. This cholesterol is naturally produced in the liver. Excess blood cholesterol received from the diet is important to avoid.
Disease
There are many diseases that can cause decreased function in the liver. Some disease like Wilson's disease, thalassemia and alpha 1-antitrypsin deficiency show up early in life due to genetic abnormalities. Due to the livers function in filtering and detoxifying blood, human actions can cause disease as well. Abuse of alcohol or other drugs can result in cirrhosis or scarring of the liver, which greatly reduces liver function over time.
Use In Diagnosis
The varied functions of the liver require many enzymes for completing the chemical processes that occur in the hepatic cells. Testing for elevated liver enzymes can help tell the doctor what is happening in the liver and whether or not it is properly functioning. MayoClinic.com lists two main liver enzymes, alanine transaminase and aspartate transaminase, for their role in the indication of liver damage in a blood test.
Regeneration
The liver has an impressive capacity to regenerate hepatic cells and adjust to function in its host. Dr. Richard A. Bowen of the Colorado State Department of Biomedical Sciences notes that the liver, from a transplanted portion, was observed to grow or shrink to the appropriate size for the animal it was transplanted into. This amazing regenerative ability is due partly to the hepatocytes of the liver having the ability to proliferate an unlimited number of times.
References
- BBC: Organs-Liver
- "Microbiology: 6th Edition"; Lansing Prescott, John Harley and Donald Klein; 2005
- University of Illinois Medical Center: Liver Disease
- MayoClinic.com: Elevated Liver Enzymes
- Colorado State University: Regeneration of the Liver
