Classwork Series and Exercises {Biology- SS3}: The Liver

LIVER

The liver is a large dark reddish-brown organ that weighs about 3 pounds, located in the upper right-hand portion of the abdominal cavity, beneath the diaphragm, and on top of the stomach, right kidney, and intestines.

There are two distinct sources that supply blood to the liver:

• Oxygenated blood flows in from the hepatic artery
• Nutrient-rich blood flows in from the hepatic portal vein

The liver holds about one pint (13 percent) of the body’s blood supply at any given moment. The liver consists of two main lobes, both of which are made up of thousands of lobules. These lobules are connected to small ducts that connect with larger ducts to ultimately form the hepatic duct. The hepatic duct transports the bile produced by the liver cells to the gallbladder and duodenum (the first part of the small intestine). The liver can lose three-quarters of its cells before it stops functioning. In addition, the liver is the only organ in the body that can regenerate itself.

Functions of the Liver

The liver regulates most chemical levels in the blood and excretes a product called bile, which helps carry away waste products from the liver. All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down the nutrients and drugs into forms that are easier to use for the rest of the body. Some of the more well-known functions include the following:

• Production of bile, which helps carry away waste and break down fats in the small intestine during digestion
• Production of certain proteins for blood plasma
• Production of cholesterol and special proteins to help carry fats through the body
• Conversion of excess glucose into glycogen for storage (glycogen can later be converted back to glucose for energy)
• Regulation of blood levels of amino acids, which form the building blocks of proteins
• Processing of hemoglobin for use of its iron content (the liver stores iron)
• Conversion of poisonous ammonia to urea (urea is an end product of protein metabolism and is excreted in the urine)
• Clearing the blood of drugs and other poisonous substances
• Regulating blood clotting
• Resisting infections by producing immune factors and removing bacteria from the bloodstream

When the liver has broken down harmful substances, its by-products are excreted into the bile or blood. Bile by-products enter the intestine and ultimately leave the body in the form of feces. Blood by-products are filtered out by the kidneys, and leave the body in the form of urine.

The Diseases of the Lever

Important diseases of the liver includes the followings

• Gall stone: are stony masses that form in the gall bladder or bile duct as a result of the production of abnormal bile by the liver. Gall stone obstruct the flow of bile and causes inflammation of the gall bladder.
• VIRAL HEPATITIS : There are two types of viral hepatitis. Hepatitis A and Hepatitis B. In both cases, the virus causes inflammation and destruction of the liver cells.
• CIRRHOSIS : This is a serious liver disease in which the damaged liver cells become replaced by useless fibrous tissue. Cirrhosis may be caused by excessive drinking of alcohol over a period.
• amoebic liver Abscess : The parasitic amoeba, Entamoeba histolytica, gets into the liver from the large intestine via the hepatic-portal vein, produces an enzyme that destroys liver tissues and causes an abscess to form.

Effects of Diseases of the Liver

The effects of liver diseases are due to the failure of liver cells to function properly. The most common signs and symptoms are:

• Weakness and tiredness
• Jaundices
• Slight fever
• Tendency to bleed and bruise easily
• High blood pressure in the hepatic-portal vein in cirrhosis.
• Mental changes such as apathy in most liver disease.

Remedy/Treatment

The liver has a high capacity to replace damaged cells and function normally. In most cases of liver diseases, the basic treatment procedures include:

• Rest, preferably in bed
• A nutritious but controlled low fat diet
• No taking of alcoholic drinks (for the rest of the patient’s life in the of cirrhosis)
• Removal of liver disorder where possible, in the case of bile duct obstruction.
• Liver transplanting

QUESTIONS

 Lets see how much you’ve learnt, attach the following answers to the comment below

1. The condition in which the liver becomes infused with fibrous tissue and is unable to repair itself is known as—————— (a) Hepatitis (b) Oedema (c) Cirrhosis (d) Amoebic liver abscess
2. The following are functions of liver except (a) Secretion of bile (b) Regulating blood clotting (c) Storage of vitamin C (d) Storage of glycogen
3. Production of bile is one of several important functions of the (a) Kidney (b) liver (c) Skin (d) Gall bladder
4. Bile is stored and concentrated in the (a) Gall bladder (b) Liver (c) Pancreas (d) Billiary apparatus
5. Which of the following is not an effect of liver disease? (a) jaundice (b) weakness and tiredness (c) acidosis (d) slight fever

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