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Immune System Structure and Functions


Immunology is the analysis of methods of the way the body defends itself from microbe infections and foreign chemicals in the surroundings. The disease fighting capability is an flexible and intricate system which includes changed in humans to protect the body against invading pathogenic micro-organisms. An infectious organism which can result in a disease is actually a pathogen and the individual or animal contaminated is named the number. The immune system needs to eliminate a pathogen without harming the host making the task very complicated and consequently with the ability to generate an enormous variety of cells and molecules which have the ability to recognise a massive range and variety of overseas invaders, as well to be able to recognize and destroy unusual cells.

The disease fighting capability is split into two parts, the non-specific system and specific system.


The non specific system is a means of combating infections. Your skin is a powerful outer barrier to many micro organisms as sweating has high ion levels which will make bacterial growth difficult. The skin also offers sebum which has an antiseptic chemical substance, as well as containing a fatty acid that halts bacterial progress.

The alimentary tract and gaseous exchange surfaces are major pathways which micro organisms can go into the body. They gather in mucus in the cilia lining and then conquer to go the mucus to the respiratory system and throat. This is an effective hurdle because they are swallowed and then killed by hydrochloric acid in the belly. Coughing and sneezing help expel foreign physiques but areas of the body not included in skin like the eyes, nose area and oral cavity are particularly susceptible to invasion bacteria.

An enzyme (lysozyme) in tears, saliva and other body essential fluids can ruin some bacteria as it bursts it by slitting molecules in the bacterial cell wall membrane. A major reason behind illness is through wounds that can be cut down by the clotting of blood vessels which prevents abnormal bleeding and blocks the entrance of micro organisms.


Phagocytosis is completed by white bloodstream skin cells called phagocytes (Macrophages, neutrophils). The procedure is in steps when certain skin cells engulf micro-organisms, other skin cells or foreign contaminants. The diagram below shows the stages of the process.

It is phagocytosis a cause bloating in the infected area. The infection is caused by mast skin cells releasing chemicals such as histamine which dilute arteries and make sure they are leaky which can develop pus or a boil. Phagocytosis will not act against infections as they reproduce inside the body's own cells where they are really protected from invasion.


The specific immune system is a second line of defence when different kinds of skin cells can distinguish between your types of micro organisms. It also has a ram system which enables its cells to replicate a response so the same type of micro organism.

Acquired immunity

Acquired immunity results from the activities of antibodies which can be proteins stated in the lymph nodes in response to antigens to provide productive immunity. The chemical which triggers a dynamic immune response is named an antigen. Antigens are mainly proteins or proteins fragments called glycoprotein that are on the surface of the cell membrane, cell wall membrane or a pathogen. These are accepted as non-self by the disease fighting capability which creates a reply. Self antigens are located in the membranes of the body skin cells. Organ donation and bloodstream transfusion are ways that antigens can be presented to someone else. A specific antibody will only behave with one kind of antigen and therefore the body needs to distinguish between different types of antigen so that the immune system can function effectively. Antigens stimulate lymphocytes to generate an immune response.

Lymphocytes originate in bone marrow from stem skin cells, move to the lymph nodes and then mature and reproduce in good sized quantities throughout life. The two types of lymphocyte are phone calls T-cells and B-cells. T-cells are prepared in the thymus gland before moving to the lymph nodes and B-cells are refined in the bone marrow and in the blood. Roughly 80% are T-cells and the rest are B-cells. Both types of skin cells have distinctive mechanisms called the humoral and cellular responses.

Cell Mediated Immunity

T cells are in charge of cell mediated immunity where they have to speak to antigens that happen to be on the surface of the body cells. You will discover special receptors on the surface which will make them able to recognise the correct antigen. Here are the main types of T-lymphocyte and there specific functions:

  • T helper cells is there to help other skin cells in the immune system. They help to stimulate and trigger B skin cells into antibody producing skin cells. If T helper cells aren't present the B skin cells cannot get into action. Another role is to enhance the action of phagocytes. In HIV the T cells are invaded which explains why there are other microbe infections with Supports.
  • T suppressor cells suppress the action of phagocytes and stop development of antibodies by the B skin cells.
  • Memory T cells have the ability to recognise and react to a pathogen when it invades and can provide long lasting immunity.
  • T Killer cells destroy cells infected with a disease before it can the perfect time to disperse. They release lymphotoxins, which cause lysis leading to the cell bursting. They also attack cells from other individuals which explains why there are rejection problems with transplant surgery.

Humoral immunity

This type of immunity is triggered by the production of antibodies from B lymphocytes. Humoral is the blood and the lymph where the antibodies circulate. In this technique your body can react to specific antigens that have been not previously in the torso. It can be weakened when there is a huge dose of the trojan as antibodies can't be produced quickly enough. Whenever a pathogenic micro organism get into your body and the lymph nodes, the B skin cells separate by mitosis and then swell to become plasma cells which produce antibodies which can be specific to the antigen which induced the response. Each antibody molecule includes four polypeptide chains; two are heavy and two light. There are two binding sites on the molecule each linking with the antigen molecule and each region that blinds together have complementing shapes like a jigsaw. Once the antibodies enter the body they circulate as immunoglobulins and form the gamma globulin small percentage of plasma protein.

Some of the turned on B cells do not develop into plasma cells and remain in the lymph nodes as ram B cells. Due to contamination these storage B skin cells develop and may survive years, so that if the disease returns they can develop into antibody producing cells. Antibody can be built up very quickly so that no symptoms show up which is the way the body becomes immune system to a disease.

Monoclonal antibodies

In the 1975 Cesar Milstein and George Kohler successfully fused antibody secreting cells with tumour cells resulting in hybridomas which secrete antibodies and are immortal. These can be cultured as a real clone and their antibodies collected. The antibodies produced and the cells that produced them are called monoclonal antibodies.

The antibodies are made by using mice. The mouse is injected with antigens to stimulate the forming of antibody producing skin cells. They are then removed from the spleen and cultured. Tumour cells from another mouse and cultured and then fused with the antibody producing skin cells. The hybridoma skin cells contain properties from both parents and then each cell is isolated independently. Each culture includes cells secreting a single antibody which can then be utilized for large range development of monoclonal antibodies.

Monoclonal means just one type and the antibody is produced in a laboratory from a single copy of any human antibody. They could be used for injecting a large amount into the body to conquer a specific disease. It is also used in finding the amount of the substance in a mixture (drug testing). In transplant surgery when there is rejection monoclonal antibodies can be used to stop specific T skin cells from working.

In tumors research monoclonal antibodies are used to find abnormal proteins on cancers cells and each antibody recognises one necessary protein and therefore different antibodies can be produced to focus on different types of cancer. The study is which makes it possible to wipe out cancer cells without harming other cells. Although cancer cells are excessive they develop from normal cells, which is why it is difficult for the immune system to identify them. Some monoclonal antibodies can attach to cancer cells making it easier for the immune system to see them. Some monoclonal antibodies can look for cells with too much development and then obstruct the cells receptors so that the cell cannot develop any further. Monoclonal antibodies can likewise have drugs or radiation attached so that they can attach to a specific cell.

Rabies and the immune system

According to the globe Health Organisation more than 55, 000 people perish of rabies each year and about 95% of human being deaths are in Asia of Africa. Nearly all deaths happen following a bite from an infected dog and between 30% and 60% of the victims are children under 15 years old. Immunizations given as soon after the infection as possible, helps prevent the starting point of rabies in 100% of exposures. Once the disease starts to show there is absolutely no treatment which is almost always fatal. The simplest way of containing the disease is through the elimination of rabies in pet dogs through creature vaccinations. In developed countries rabies is transported mainly through wild animals and in the past few years the condition has turned into a medical condition in Americas and European countries.

The computer virus is a zoonotic disease (transferred from family pets to humans) which is transmitted through bites and scrapes. The first symptoms are flu-like such as a fever and pain. The disease then goes to the respiratory system, gastrointestinal and/or central nervous system and finally brings about hyperactivity or paralysis and then to a coma and loss of life in all instances, usually credited to breathing failure. Fatality usually happens in the first a week of the illness.

The virus likes to harm nerves and can get there by going right through a mucous membrane when the nerves are near to the surface; they are areas like the nasal area, lips and eye. The non specific disease fighting capability can prevent this transmitting most of the time, but generally the disease is transferred through creature bites. The trojan likes to live in the saliva and with helps it be solid and foamy in the pet carrying the trojan. The disease takes a while to discover a nerve to attack, this is called the incubation period and sometimes the human being won't get suffering. When rabies does indeed attack it trips in the nerves to the spinal-cord and then to the mind although sometimes the pathogen hides from the immune system until it is too later. The virus is aware nerves are usually not checked for bacteria by the immune system and for that reason it may well not be recognised right away. It tips the immune system by concealing and by the time the enemy will there be it is too past due, which explains why any bite from an creature needs to be check out immediately. Once the trojan reaches the brain it multiplies and can make the afflicted person or animal crazy. After that it vacations through other nerves to turn out the saliva glands.

Wound cleansing and immunizations after contact with an infected dog can prevent the onset of the condition in all circumstances. Rabies can be treated by immunoglobulin vaccines, or antibody which is employed in category III cases where there have been a number of bites, scratches, licks on busted pores and skin or other connections that break the skin. The WHO says that vaccines are costly and are in short supply in many developing countries.


Immunity can be energetic natural (connection with disease), which is long-term and antigen specific. Artificial (immunization), which produces slowly and can go on for years. Passive natural (transplacental), which produces immediately and is also temporary. Passive manufactured (treatment) which evolves immediately and is temporary.


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  • Patient UK 2010, (Online), Available at: http://www. patient. co. uk/doctor/Rabies-Vaccination. htm (Accessed 11 Mar 2010).
  • Rabies -Free World Inc 2007, (Online), Available at: http://www. rabiesfree. org (Accessed 11 Mar 2010).
  • Roberts, R. Reiss, M and Monger, G. (1993) Biology- Principles and Operations, Thomas Nelson and Sons Ltd: Surrey.
  • Simpkins, J. and Williams, J. I. (1995) Advanced People Biology, Collins Educational: London.
  • University of Hartford 2010, (Online), Available at: http://uhaweb. hartford. edu/bugl/immune. htm (Accessed 3 Mar 2010).
  • World Health Organisation 2010, (Online), Available at: http://who. int/mediacentre. factsheets/fs099/en/ (Accessed 11 Mar 2010).
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