Actions for this page Listen Print. Summary Read the full fact sheet. On this page. The immune system and microbial infection Parts of the immune system The body's other defences against microbes Fever is an immune system response Common disorders of the immune system Immunisation Where to get help. The immune system and microbial infection The immune system keeps a record of every microbe it has ever defeated, in types of white blood cells B- and T-lymphocytes known as memory cells.
Parts of the immune system The main parts of the immune system are: white blood cells antibodies complement system lymphatic system spleen bone marrow thymus. White blood cells White blood cells are the key players in your immune system.
Antibodies Antibodies help the body to fight microbes or the toxins poisons they produce. Complement system The complement system is made up of proteins whose actions complement the work done by antibodies. Lymphatic system The lymphatic system is a network of delicate tubes throughout the body.
The main roles of the lymphatic system are to: manage the fluid levels in the body react to bacteria deal with cancer cells deal with cell products that otherwise would result in disease or disorders absorb some of the fats in our diet from the intestine. The lymphatic system is made up of: lymph nodes also called lymph glands -- which trap microbes lymph vessels -- tubes that carry lymph, the colourless fluid that bathes your body's tissues and contains infection-fighting white blood cells white blood cells lymphocytes.
Spleen The spleen is a blood-filtering organ that removes microbes and destroys old or damaged red blood cells. Bone marrow Bone marrow is the spongy tissue found inside your bones.
Thymus The thymus filters and monitors your blood content. The body's other defences against microbes As well as the immune system, the body has several other ways to defend itself against microbes, including: skin - a waterproof barrier that secretes oil with bacteria-killing properties lungs - mucous in the lungs phlegm traps foreign particles, and small hairs cilia wave the mucous upwards so it can be coughed out digestive tract - the mucous lining contains antibodies, and the acid in the stomach can kill most microbes other defences - body fluids like skin oil, saliva and tears contain anti-bacterial enzymes that help reduce the risk of infection.
The constant flushing of the urinary tract and the bowel also helps. Fever is an immune system response A rise in body temperature, or fever , can happen with some infections. Common disorders of the immune system It is common for people to have an over- or underactive immune system.
Overactivity of the immune system can take many forms, including: allergic diseases - where the immune system makes an overly strong response to allergens.
Allergic diseases are very common. They include allergies to foods, medications or stinging insects, anaphylaxis life-threatening allergy , hay fever allergic rhinitis , sinus disease, asthma, hives urticaria , dermatitis and eczema autoimmune diseases - where the immune system mounts a response against normal components of the body.
Autoimmune diseases range from common to rare. They include multiple sclerosis, autoimmune thyroid disease, type 1 diabetes, systemic lupus erythematosus, rheumatoid arthritis and systemic vasculitis.
Immunoglobulin therapy Immunoglobulins commonly known as antibodies are used to treat people who are unable to make enough of their own, or whose antibodies do not work properly. Immunisation Immunisation works by copying the body's natural immune response. Together, these factors are referred to as HALO, which is defined as: health - some health conditions or factors may make you more vulnerable to vaccine-preventable diseases.
For example, premature birth, asthma, diabetes, heart, lung, spleen or kidney conditions, Down syndrome and HIV will mean you may benefit from additional or more frequent immunisations age - at different ages you need protection from different vaccine-preventable diseases.
The vessel dilation allows more white blood cells to leave the bloodstream and enter the infected tissues. Phagocytes then do the job of consuming invading microbes. This rapid response by the body to an infection is an example of innate immunity. Activated B cells multiply to produce large numbers of clones, most of which become plasma cells. Plasma cells produce antibodies that recognize antigens on foreign microbes. The antibodies act as tags to identify the invaders.
This is called an antibody-mediated response. T cells, activated by antigens presented by phagocytes, multiply then seek out and destroy infected cells. This is called a cell-mediated response. A few of the B cell and T cell clones are modified to populate lymph organs so that they can respond quickly in the future if the pathogen returns. In this way, the adaptive immune system "remembers" the pathogen involved. A decrease in neutrophils during chemotherapy, known as chemotherapy-induced neutropenia , increases the risk of serious infection.
Neutropenia makes it more difficult for the body to fight off infections. As a result, bacteria that are normally not very harmful can cause serious illness. White blood cells are an important part of our immune system. Different types of white blood cells perform different functions in the body. Overall, white blood cells help to protect us against bacteria, viruses, and parasites.
A high white blood cell count is usually a sign of an infection or illness. A low white blood cell count can indicate another type of problem. Low white blood cell counts can leave you vulnerable to serious infections. Chemotherapy is a common cause of low white blood cell counts. Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life.
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Library of Medicine. White blood cell count. Updated September 1, Your Privacy Rights. As phagocytes do this to all pathogens that they encounter, we call them 'non-specific'. Lymphocytes are another type of white blood cell. They recognise proteins on the surface of pathogens called antigens. Lymphocytes detect that both the proteins and pathogens are foreign, not naturally occurring within your body and produce antibodies.
This can take a few days, during which time you may feel ill. The antibodies created by the lymphocytes cause pathogens to stick together, and make it easier for phagocytes to engulf them. A specific type of lymphocyte called a memory lymphocyte can 'remember' the antigens from an infection by a previous pathogen.
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