Immune system

The immune system is the body’s natural defense that protects us from germs and diseases. Every day, we come in contact with bacteria, viruses, and other tiny organisms that could make us sick. The immune system acts like a security team that guards the body, always watching for invaders and reacting when danger appears.

The immune system is made up of many parts that work together. Important parts include the white blood cells, lymph nodes, bone marrow, spleen, and skin. White blood cells are like soldiers that move through the blood and tissues, searching for and attacking germs. The bone marrow makes new blood cells, while the lymph nodes and spleen act as filters to catch and destroy harmful materials.

When a germ, such as a virus or bacterium, enters the body, the immune system recognizes it as something foreign. It then produces special proteins called antibodies. These antibodies attach to the invader and mark it so that other immune cells can destroy it. Once the body has fought off the infection, it remembers the germ. This is called immunity. If the same germ tries to attack again, the body responds faster and usually prevents illness.

There are two main types of immunity: innate immunity and adaptive immunity. Innate immunity is the body’s first line of defense—it includes the skin, mucus, and general white blood cells that react quickly to any threat. Adaptive immunity develops over time as the body learns to recognize specific germs. Vaccines use this idea by safely introducing a tiny, harmless part of a germ so the body learns to fight it later.

The immune system also has to be careful not to attack the body itself. Sometimes, when it becomes confused, it may start attacking healthy cells by mistake, which leads to autoimmune diseases. On the other hand, if the immune system becomes too weak, it cannot fight infections properly, which can make a person sick more easily.

Keeping the immune system strong involves a healthy lifestyle. Eating nutritious food, getting enough sleep, washing hands, exercising regularly, and reducing stress all help the immune system work better. Although we cannot see it, the immune system is always active, quietly protecting us and keeping our bodies safe from harm.