The Immune System

The immune system is a complex and dynamic network of organs, white blood cells, proteins, and chemicals that work together to protect the body from harm. Its primary functions include identifying and neutralizing harmful invaders, minimizing the damage they cause, promoting healing from infections and injuries, and adapting to future threats. These invaders can be bacteria, viruses, fungi, parasites, or toxins. A healthy immune system is finely tuned to distinguish between the body’s own cells and those that don’t belong. When a threat is detected, it activates and mobilizes immune cells to attack and eliminate the invaders. Once the danger has passed, the immune system shuts down the response to prevent unnecessary damage to the body. Importantly, it also "remembers" these invaders by developing antibodies, enabling a faster, more effective response if the same threat reappears in the future. This ability to recognize, respond, and remember is what makes the immune system such a powerful and adaptive defense mechanism.

Many parts of the body make up the immune system. 

• White Blood Cells: These immune system cells attack and eliminate harmful germs. There are many types of white blood cells, each with a specific mission and a different way of recognizing a problem and communicating with other cells. 
• Antibodies: These proteins protect the body from invaders by binding them to help destroy them. 
• Cytokines: These proteins act as chemical messengers that tell the immune cells where to go and what to do. Different types of cytokines do specific tasks. 
• Complement System: This system is a group of proteins that collaborates with other cells to defend against invaders and promote healing from injury or infection. 
• Lymph Nodes & Lymph System: Lymph nodes are small bean-shaped organs that act like strainers to filter waste products from the fluid in the body, which drains from tissues and cells while keeping good components like nutrients. There are hundreds of lymph nodes throughout the body. 
• Spleen: This organ stores white blood cells that defend the body from invaders. It also filters the blood to help recycle old and damaged cells to make new ones. 
• Tonsils & Adenoids: These help trap invaders as soon as they enter the body.
• Thymus: This small organ helps T-Cells mature before being sent to the body for protection. 
• Bone Marrow: Bone marrow is like a factory for blood cells. It makes the blood cells the body needs to survive, including white blood cells. 
• Skin: The skin is a protective barrier that helps to stop germs from entering the body. 
• Mucosa: This membrane has three layers and lines the cavities and organs throughout the body. It secreted mucus to capture invaders to remove them. 
• Peyer’s Patches: These immune system components are in the mucus membrane of the small intestine. They help to monitor harmful microbes, bacteria, and substances in the digestive tract.

There are two parts to the immune system. The innate immune system is the protection the body is born with. It is the body’s first line of defense. It responds to invaders quickly by attacking any organism that shouldn’t be in the body. It doesn’t need any prior training or knowledge to tell the difference between cells belonging to the body and those not. The white blood cells involved in this part of the system don’t learn to recognize certain invaders, they have no memory of attacking invaders and don’t offer protection against specific germs. That is where the second part of the immune system comes into play. 

The second part of the immune system is called acquired immunity, also known as adaptive or specific immunity; this part of the immune system protects the body by acquiring knowledge over time through exposure. Certain white blood cells called lymphocytes remember specific invaders and can tell when they don’t belong in the body.