Wikijunior:Human Body/ImmuneSystem
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The immune system is not a single object like many of the other organs discussed in this book but a lot of cells dispersed throughout the body to protect us from infections and tumor formation.
[edit] What does the immune system look like?
The immune system is not visible to the naked eye for most of its part because it is composed of a lot of solitary cells which wander and patrol the body and cooperate to eliminate bacteria viruses and cells of the body that have become sick. This is why the immune system is called system rather than organ. The only structures that can sometimes be seen and felt are lymph nodes and the thymus. Lymph nodes are little spherical organs where immune cells gather to exchange information and to proliferate in case of infection. The proliferation of immune cells in the lymph node lead to its enlargement.
[edit] What are the parts of the immune system?
The immune system is composed of white blood cells, lymph nodes, the bone marrow and the thymus.
[edit] What is the function of the immune system?
The immune system is the police of the body. Almost every cell and space in the body is patrolled for intruders and abnormalities. Specialized cell types carry out certain functions:
- Macrophages devour bacteria, viruses, abnormal cells and debris. They warn T-cells about viruses and bacteria.
- T-cells patrol cells of the body and make sure they are o.k. They get signals from macrophages. T-cells coordinate a lot of the immune response. They tell B-cell to produce antibodies and they can kill abnormal cells that are then absorbed by macrophages.
- B-cells produce antibodies. Antibodies are small molecules that attach to certain structures at other cells like bacteria. By clotting the surface of bacteria they become inactive and can be devoured by macrophages. Each B-cell produces a specialized antibody that targets a specific bacteria or virus. Once a B-cell became active it stays on alert. This is why you suffer from a children's disease only once and why you are immune to a common cold in winter after you went through it.
There three types of organs that are part of the immune system:
- The bone marrow is where all blood cells of the immune system are produced.
- The thymus is the training station of the T-cells. Here, T-cells learn to distinguish between structures that belong to the body and foreign cell structures of bacteria and viruses.
- Lymph nodes are communication centers of the immune cells. Here macrophages inform T-cells which in turn trigger B-cells to produce antibodies. There multiple lymph nodes in the human body such that close to every part of the body there is such a communication center.
[edit] What organ systems is the immune system connected with?
Immune cells have the privilege to be able to visit almost any part of the body. Like the police they have special rights. Immune cells can travel in blood vessels but if they come close to a place where an infection occurs they can leave a capillary to travel right to the place of action and take part in the scuffle.
[edit] How does the immune system interact with other parts of the body?
T-cells patrol normal human cells. They do so by snuggling a cell and telling it to show part of what is inside. You can think of this as a passport control. The T-cell has to decide whether the passport is correct or not, thereby deciding whether the cell is normal or not. Apart from this, the immune system mostly deals with intruders from the outside. They have to be identified and after this the immune system is quite rigorous in eliminating those intruders. Records are kept by some T-cells to make sure next time the same intruder is expelled even more rapidly, sometimes without us noticing.
[edit] How can you keep your immune system healthy?
The immune system is quite fragile and depends on a lot on our mood and not being in stress. Avoid getting too little sleep and try not getting harmful stress that makes you feel nervous. Spend time with friends and in friendly, safe places.
