THE IMMUNE SYSTEM BLOOD CELLS AND BLOOD VESSEL

Transcription

1 THE IMMUNE SYSTEM The immune system is made up of a network of cells, tissues, and organs that work together to protect the body and fight illnesses and disease. The Function of the Immune System The immune system is the body's defense against infectious organisms and other invaders. Its job is to attack, and kill or remove foreign organisms and substances that invade body systems and cause disease. Everybody has an inbuilt immune system which protects it from diseases and germs. This system has a lot of different parts which work together to keep out any harmful germs, and attack and destroy any which manage to get inside your body BLOOD CELLS AND BLOOD VESSEL

2 ORGANS OF THE IMMUNE SYSTEM

3 Causes of Illness and Disease When germs, like viruses and bacteria, get into your body and take over, you end up with an infection. The symptoms of your infection depend on where it is. For example, if the germs have attacked your throat, your throat may feel very sore. VIRUS A virus is a microscopic particle that can invade a cell, then use the cell s contents to clone itself millions of times before bursting out of the cell and infecting more cells in the same way. In the process, the original cells of the host organism are destroyed. Viruses cause infections like chicken pox, measles, and AIDS. HIV and AIDS are diseases that destroy the Immune System. BACTERIA Bacteria are microscopic organisms. They are the simplest form of life on the planet. Each bacterium (singular of bacteria) is made up of a single cell. Some bacteria can cause infections which are fought off by your immune system, sometimes with the help of antibiotics. Other bacteria are good, like the bacteria in your digestive system that help you to digest food. Harmful bacteria give off poisons that upset the normal functions of the body, or injure and kill the cells in our bodies. CONGENITAL ILLNESS or DISEASE - Not all illnesses are caused by infection. Some people are born with certain illnesses. Some of these include certain forms of heart disease. Illnesses or diseases that people are born with are described as congenital.

4 HOW THE IMMUNE SYSTEM WORKS Your body has three layers of defense: The skin, and mucous membranes; swelling and fever; and white blood cells. FIRST LAYER OF DEFENSE The skin and mucous membranes act as a barrier to many of the germs in the environment around us. This is the body s first layer of defense.

5 SECOND LAYER OF DEFENSE Swelling and fever occur when cells that have been infected by harmful germs produce a chemical that causes the blood vessels to become wider. This widening causes more of the body s main defenders white blood cells - to rush to the area to fight the infection. As a result, the area swells, gets red, and becomes warm and painful. If this happens over the whole body, we get a fever. The fever is the body s way of fighting bacteria and viruses. The higher temperature slows the growth of the bacteria or virus. Swelling and fever are the body s second line of defense. SWELLING AND FEVER: SECOND LAYER OF DEFENSE

6 THIRD LAYER OF DEFENSE White blood cells (leukocytes) are the main defenders of the body. They are your body s third layer of defense. Your immune system works by recognizing any cells that aren't human, (like germs, viruses, and bacteria), and destroying them. The white blood cells are continually on the lookout for signs of disease in the form of antigens, which are Whenever a germ or infection enters the body, the white blood cells snap to attention and race toward the scene of the crime. When a germ does appear, the white blood cells have a variety of ways by which they can attack: Some white blood cells, called phagocytes, surround and swallow the bacteria. When this happens, poisons from the bacteria can sometimes kill some of the leukocytes. The collection of dead white blood cells and dead bacteria form the yellow substance that we call pus. How a Phagocyte Works Other white blood cells (lymphocytes) produce protective chemicals called antibodies that overpower the antigen. An antigen is any substance in the body that causes your white blood cells to produce antibodies. An antigen may be a bacterium or virus, or the chemical or poison they produce. Each type of antibody is very

7 specific, and can recognize only a certain type of antigen. Once the antibody finds it, it gets rid of the antigen so it can't hurt you. Even after you are better, certain lymphocytes can remember how to make the special antibody so that if the same germ infects you again, it can be killed even faster! How a Lymphocyte Works DRUGS THAT HELP THE IMMUNE SYSTEM A drug is a chemical taken into the body that affects how the body functions. When bacteria and viruses produce more than our systems can fight off, we use helpful drugs, called medicines, to help the immune system fight the disease. Antibiotics, for example, are helpful drugs. NEGATIVE HABITS THAT AFFECT THE IMMUNE SYSTEM Not all drugs are medicines, and many are harmful. The misuse of drugs is called drug abuse. Drug abuse harms the body. Two drugs that are abused all over the world are alcohol and nicotine.

8 Alcohol decreases brain cell activity - it changes a person's ability to think, speak, and see things as they really are. Over a period of time, the abuse of alcohol can lead to: * stomach and intestine problems * liver damage * nerve and muscle damage * heart problems * brain damage Alcohol can cause everything from blackouts to permanent loss of brain functions and memory. * Cancer long term drinking has been linked to cancer of the throat, mouth, liver, esophagus and larynx. * emotional and psychological problems, such as sadness, depression, and even hallucinations (seeing and hearing things or people that are not real). Nicotine is found in tobacco, usually in the form of cigarettes, cigars and snuff. It is usually inhaled (breathed in) by smoking. Nicotine is harmful because it increases the rate of the heartbeat, and it affects the respiratory system. Over a period of time, such smoking can lead to heart disease, stroke, emphysema (breakdown of lung tissue), and many types of cancer including lung, throat, stomach, and bladder cancer. People who smoke nicotine also have an increased risk of infections like bronchitis and pneumonia. Other drugs - The abuse of other drugs is increasing among people in The Bahamas and the western world. Two illegal drugs that are used very frequently are Cocaine and Marijuana. These are two very dangerous drugs. These are two very dangerous drugs. They affect the nervous system by destroying brain cells, and the immune system by reducing the body s ability to fight off diseases. Abuse of these drugs can weaken the body s defense systems so severely that an attack from an illness or disease may lead to death.