The immune system is a complex network of organs, cells, and proteins that defends the body against infections and other harmful substances. It is made up of two main parts: the innate immune system, which you are born with, and the adaptive immune system, which you develop when your body is exposed to microbes or chemicals released by microbes. These two immune systems work together to protect the body from foreign invaders such as bacteria, viruses, fungi, and toxins.
The innate immune system is the first line of defense against invaders. When it recognizes an invader, it goes into action right away by surrounding and covering the invader, and then killing it inside the immune system cells called phagocytes. The acquired immune system, with help from the innate system, makes special proteins called antibodies to protect the body from a specific invader. These antibodies are produced after the body has been exposed to a specific germ, and they help the body remember the invader and destroy it if it enters the body again.
The immune system keeps a record of every germ it has ever defeated so it can recognize and destroy the microbe quickly if it enters the body again. Abnormalities of the immune system can lead to allergic diseases, immunodeficiencies, and autoimmune disorders. The immune system is made up of various organs, cells, and proteins, and each cell type plays a unique role in recognizing problems, communicating with other cells, and performing its functions.
