They circulate in the body in blood vessels and the lymphatic vessels that parallel the veins and arteries. White blood cells are on constant patrol and looking for pathogens. When they find a target, they begin to multiply and send signals out to other cell types to do the same.
Our white blood cells are stored in different places in the body, which are referred to as lymphoid organs. These include the following:.
These cells surround and absorb pathogens and break them down, effectively eating them. There are several types, including:. Lymphocytes help the body to remember previous invaders and recognize them if they come back to attack again.
Lymphocytes begin their life in bone marrow. Some stay in the marrow and develop into B lymphocytes B cells , others head to the thymus and become T lymphocytes T cells. These two cell types have different roles:. The immune system needs to be able to tell self from non-self. It does this by detecting proteins that are found on the surface of all cells.
It learns to ignore its own or self proteins at an early stage. In many cases, an antigen is a bacterium, fungus, virus, toxin, or foreign body. But it can also be one of our own cells that is faulty or dead. Initially, a range of cell types works together to recognize the antigen as an invader. Antibodies are special proteins that lock on to specific antigens. Each B cell makes one specific antibody. For instance, one might make an antibody against the bacteria that cause pneumonia , and another might recognize the common cold virus.
Antibodies are part of a large family of chemicals called immunoglobulins, which play many roles in the immune response:. Antibodies lock onto the antigen, but they do not kill it, only mark it for death. The killing is the job of other cells, such as phagocytes. The immune system is the body's defense against infections. Many cells and organs work together to protect the body. White blood cells, also called leukocytes LOO-kuh-sytes , play an important role in the immune system.
Some types of white blood cells, called phagocytes FAH-guh-sytes , chew up invading organisms. Others, called lymphocytes LIM-fuh-sytes , help the body remember the invaders and destroy them.
One type of phagocyte is the neutrophil NOO-truh-fil , which fights bacteria. When someone might have bacterial infection, doctors can order a blood test to see if it caused the body to have lots of neutrophils. Other types of phagocytes do their own jobs to make sure that the body responds to invaders.
The two kinds of lymphocytes are B lymphocytes and T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells, or go to the thymus gland to mature into T cells. Lymph nodes. Small organs shaped like beans, which are located throughout the body and connect via the lymphatic vessels. Lymphatic vessels. A network of channels throughout the body that carries lymphocytes to the lymphoid organs and bloodstream.
Antibiotics can be used to help your child's immune system fight infections by bacteria. Antibiotics were developed to kill or disable specific bacteria. That means that an antibiotic that works for a skin infection may not work to cure diarrhea caused by bacteria. Using antibiotics for viral infections or using the wrong antibiotic to treat a bacterial infection can help bacteria become resistant to the antibiotic so it won't work as well in the future. It is important that antibiotics are taken as prescribed and for the right amount of time.
If antibiotics are stopped early, the bacteria may develop a resistance to the antibiotics and the infection may come back again. The main parts of the immune system are: white blood cells, antibodies, the complement system, the lymphatic system, the spleen, the thymus, and the bone marrow. These are the parts of your immune system that actively fight 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. This means it can recognise and destroy the microbe quickly if it enters the body again, before it can multiply and make you feel sick. Some infections, like the flu and the common cold, have to be fought many times because so many different viruses or strains of the same type of virus can cause these illnesses.
Catching a cold or flu from one virus does not give you immunity against the others. White blood cells are the key players in your immune system. They are made in your bone marrow and are part of the lymphatic system.
White blood cells move through blood and tissue throughout your body, looking for foreign invaders microbes such as bacteria, viruses, parasites and fungi. When they find them, they launch an immune attack. White blood cells include lymphocytes such as B-cells, T-cells and natural killer cells , and many other types of immune cells.
Antibodies help the body to fight microbes or the toxins poisons they produce. They do this by recognising substances called antigens on the surface of the microbe, or in the chemicals they produce, which mark the microbe or toxin as being foreign. The antibodies then mark these antigens for destruction. There are many cells, proteins and chemicals involved in this attack.
The complement system is made up of proteins whose actions complement the work done by antibodies. The lymphatic system is a network of delicate tubes throughout the body. The main roles of the lymphatic system are to:. The spleen is a blood-filtering organ that removes microbes and destroys old or damaged red blood cells. It also makes disease-fighting components of the immune system including antibodies and lymphocytes.
Bone marrow is the spongy tissue found inside your bones. It produces the red blood cells our bodies need to carry oxygen, the white blood cells we use to fight infection, and the platelets we need to help our blood clot. The thymus filters and monitors your blood content. It produces the white blood cells called T-lymphocytes. As well as the immune system, the body has several other ways to defend itself against microbes, including:. A rise in body temperature, or fever , can happen with some infections.
This is actually an immune system response. A rise in temperature can kill some microbes.
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