The human immune system is the best doctor in the world.

When the immune system is weak, we are susceptible to illnesses and recovery takes a longer time. However, when our immune system is strong, we are able to fight illnesses without much effort.

The human immune system is not a specific organ, cell or biological substance. It doesn’t exist as an explicit part of our body. On the contrary, the immune system is a complex make-up of the lymphoid organs and lymphocytes. They work together to produce a range of different substances at different timing. The entire immune system is very complex, but they work together so flawlessly that it’s not replicable by anyone or any machine.

Think of the immune system as an army with different types of soldiers, attacking the enemies with different weapons. The immune system works 24 hours a day to protect us from “invaders” such as bacteria, viruses, parasites, pollutants and even dead cells.

Our body’s main lymphoid organs are the bone marrow and thymus. The bone marrow produces red blood cells and white blood cells. White blood cells are our immune cells. Just like how we train soldiers, air force and navy to win wars, lymphocytes, also known as T cells, are trained in our thymus to perform various special tasks.

The immune system also includes other peripheral lymphoid organs such as the tonsils, spleen, lymph nodes and appendix. For example, when a lymph node swells, it reflects that our immune cells are fighting an infection.

T cells are one of the immune cells, it targets and destroy different “invaders” differently. T cells act on invading bacteria by releasing different antibodies. The antibodies will eventually bind to the bacteria and destroy it.

Another interesting type of immune cells are macrophages. Macrophages acts as transmitters as well as fighters. When it encounters enemies, it will summon other immune cells to gather on the battlefield as well as fight the enemy itself. It will catch the enemy by its tentacles and swallow them. Apart from this, there are many other types of T cells, one of the powerful T cells is known as NK cell or natural killer cell. It kills enemies by producing and releasing certain substances.

The immune system is very brilliant and doesn’t stop protecting us from deadly enemies.

Without the protection of the immune system, we would struggle to even survive a few hours.

Why do so many people still suffer from life-threatening diseases when our body is protected by such a huge and sophisticated “army”?

The reason lies in the disorder of their immune system.