Essay/Term paper: The liver

Essay, term paper, research paper:  Biology

The Liver:
Facts, Functions, and Structure of





Justin Amos
Anatomy/ Physiology
October 24, 1997











Facts and Functions
The liver is the largest organ in the entire, normal human body. It weighs anywhere from 2.5 to 3.3 pounds. With its large size it is also a very resilient organ. Up to 3/4 of its cells can be removed before is ceases to function. It is red-brown organ roughly shaped like a cone. The liver is located in the upper right abdominal cavity immediately beneath the diaphragm. Without the liver, we could not survive. It serves as the body"s chemical factory and it regulates the levels of most of the main chemicals in the blood. It is classified in the digestive system, because of the bile it produces. Bile is produced in the liver and stored in the gallbladder. Although it contains no digestive enzymes, bile does dilute and neutralize stomach acid, and it increases the efficiency of fat digestion and absorption. The liver is the organ that allows us to drink alcohol. With the help of the kidneys, the liver clears the blood of drugs, alcohol, and other poisonous substances by absorption. It then alters the chemical structure of the substance absorbed, makes them water soluble, and excretes it in the bile. From there, the bile carries waste, including the absorbed substance, to the small intestine, taking a pitstop at the gallbladder, where it also helps in the breakdown and absorption of fats present.
The liver also produces albumin, compliment, coagulation factors, and globin; all important proteins for blood plasma. Albumin regulates the exchange of water between blood and tissues. Compliment is a group of proteins that plays a part in the immune system"s defenses against infection. Coagulation factors enable blood to clot when a blood vessel wall is damaged. Globin is a major component of the oxygen-carrying pigment hemoglobin. Yet another function of the liver is to produce synthesized cholesterol and special proteins that carry fats around the body.
Along with producing many important substances, it also stores a lot of important substances as well. It receives glucose ,not immediately needed, from the hepatic portal vein and stores it as glycogen. When the body needs more energy and heat, the liver converts the stored glycogen back to glucose and releases it into the bloodstream to be used. As with the blood, the liver also regulates the blood level of amino acids, chemicals that form the building blocks of proteins. After we eat a meal, our blood contains too high a level of amino acids. The liver converts some of these acids into glucose, proteins, other amino acids, and urea, which is passed to the kidneys for excretion in the urine.

Structure
The liver contains two main lobes, left and right, which are separated by the falciform ligament, a connective tissue septum. The liver also consists of two minor lobes, caudate and quadrate. Oxygenated blood flows into the liver through an artery called the hepatic artery and nutrient-rich blood via the portal vein. From there, the blood drains into the hepatic vein carrying carbon dioxide and plasma proteins. Bile made by liver cells and carrying all of those harmful substances is excreted through a network of ducts called the bile ducts. As these ducts grow larger, they fuse to form fight and left hepatic ducts which join and carry the bile to the gallbladder. The smaller bile ducts inside the liver, and branches of the hepatic artery an portal vein form the portal tracts, a kind of conduit system.

Compliments
As the liver is one of the most important organs, it must be taken good care of. Liver abscesses are a common liver disorder. It is a localized collection of pus in the liver and can be caused by a diverticular disease or appendicitis and invasion by amebae, one-celled parasites; although, sometimes the cause cannot by identified. The abscess can usually be drained through a needle inserted through the abdominal wall and guided by ultrasound. Abdominal surgery is the other option.
Another liver compliment is liver cancer. This is a malignant tumor in the liver. More commonly in the U.S., liver cancer, arises from a primary tumor in another organ. One way to fix this condition would be to completely remove the tumor where cirrhosis isn"t present, but that is a very rare condition. Cirrhosis is a chronic disease of the liver characterized by the replacement of normal tissue with fibrous tissue and the loss of functional liver cells. More commonly used are anticancer drugs, which help victim survive longer. Also a liver transplant can be done, as well. There is no cure for secondary liver cancer, but anticancer drugs will slow down the decay.
Yet another liver disease is alcoholic liver disease. This occurs when damage is caused to the liver because of persistent heavy alcohol consumption. This can progress to cirrhosis, severe structural damage, loss of liver function, and eventually death.
With all of the liver"s important functions it is obviously a major organ, and one to be taken seriously. The liver must not be abused, because if it is the body will be damaged greatly and possibly destroyed.














Bibliography
Clayman, Charles B., ed. Home Medical Encyclopedia. New York, NY: Dorling Kindersley Limited and the American Medical Association, 1989: 644-647.
Seeley, Rod R. Essentials of Anatomy and Physiology. St. Louis, MO: Mosby- Year Book, Inc., 1991: 413.
Volume 8, Compton"s Pictured Encyclopedia. Chicago, IL: F.E. Compton & Company, 1961: 313.