The immune system is the body's defense against bacteria, viruses, and other pathogens. It is made up of white blood cells, organs, and tissues that work together to identify foreign substances in the body. There are two main types of white blood cells - phagocytes that attack pathogens directly, and lymphocytes that recognize specific pathogens and help the body destroy them. The immune system is located throughout the body and involves organs like the thyroid and adrenal glands. When pathogens invade the body, immune cells work together to produce antibodies that lock onto the pathogens and mark them for destruction. This immune response remains in the body in case of future infections. However, cancers can also develop from immune cells themselves, such as lymphomas and leukem

1. Immune Systems<br /> <br />White blood cellAdrenal glandsThyroid gland<br />What is Immune System?<br />Immune system is a body’s defense against from millions of bacteria, organisms, and other invaders that would love to invade human’s body. It attacks the organisms and substances that invade body systems and cause diseases. They made up of a network of cells, organs and tissues that work together to protect your body. The cells involved the white blood cell (picture above) or in scientific word leukocytes, which two basic types that combine to destroy disease organisms. The two basic types were phagocytes, which is the cells that attack the invader organisms and lymphocytes, which is the cells that recognize the invaders organisms and help the body to destroy them. There are two kinds of lymphocytes that are B-lymphocytes and T-lymphocytes. The purpose for B-lymphocytes is seeking out the disease organisms target and sending defenses to lock onto them. For T-lymphocytes, they are like the soldiers that destroy the disease organisms. <br />The size of these organisms is like the size of molecules. It’s very small that you need to use microscope to see it better. The immune system located throughout human’s body. It has to do with human’s thyroid and adrenal glands (picture above). It has millions of it in human’s body. <br />How does it work?<br />When the substances that invade the body, several type of cells work together recognize them and respond. These cells cause the B-lymphocytes to produce antibodies that make the proteins to lock onto them in the antigens. Once it produced, it continued exists in human’s body, so that if the same antigens appear to immune systems, the antibodies do their job. So if someone gets sick by chickenpox, that person doesn’t get sick from it again. It also helps to protect the person from the future attack by the germs or substance that produces that certain diseases. Some T-lymphocytes are actually called “killer cells”. The job is like phagocytes attack the invader organisms. Sometimes, antibodies can neutralize toxins (poisonous) produced any organisms. There’s solution for this. It can activate a group of protein called complements that are also part of immune system. It assists for killing the bacteria, viruses and infected cells. <br />Immune system helps human’s body from the deadly diseases. So if human doesn’t have immune system in their body, they won’t live for very long. <br />Cancers of the Immune System<br />Cancer happens when cells grow out of control. It also can happen with cells of immune system. Lymphoma includes the lymphoid tissues and one of the most common childhood cancers. Leukemia, which is including unusual overgrowth of leukocytes, is the one common childhood cancers too. It usually happens in kids and teens. Although, the immune system can’t prevent this illness, but you can help your child’s immune system to stay stronger and fight illness by working closely with your doctor.<br />