When it comes to our immune system and how strong our immunity may or may not be, we're mostly aware that we can support a healthy immune system by eating more of the right things (fruits and vegetables) and less of the not-so-right things (fried, processed foods high in fat, salt and sugar).
But when it comes to knowing what the immune system actually is, or even where it is, most of us come unstuck. So we're here to put that right.
What Is the Immune System?
The immune system is a complex system made up of many different elements. It's a network of cells, molecules, tissues and organs that extend throughout the entire body, and each part, however tiny, has a crucial role to play in keeping us healthy.
There are two "branches" of the immune system – the innate immune system and the adaptive immune system. They work together to defend the body against pathogenic bacteria, fungi and viruses, and other foreign invaders.
The Innate Immune System vs the Adaptive Immune System
The innate immune system is our "seek and destroy" defence, working continuously to find pathogens and foreign objects that don't belong, and doing its best to destroy them before they make us sick.
The adaptive immune system works more like a memory bank, recognising pathogens and disease-causing agents we've encountered before, and sending signals to the innate immune system to help destroy them if we come into contact with them again.
The Different Elements of the Immune System
Going back to the complex arrangement of cells, molecules, tissues and organs that make up both branches of the immune system – each has a specific role, and without it, we'd be more susceptible to illness and disease.
The cells of the immune system are mainly different types of white blood cells. Each helps the immune system identify, recall and destroy pathogens, or signals to other parts of the immune system that there's a threat needing attention. These cells include B cells, killer T cells, macrophages and CD4 helper cells.
When immune cells signal that there's an invading pathogen, the resulting immune response involves molecules called antibodies. The body creates antibodies to a specific pathogen – a particular flu strain, for example – so that if we come into contact with that same strain again, we can fight it off more effectively using those antibodies.
Other molecules of the immune system are called cytokines. These are released during an immune response and act as chemical messengers between cells, tissues and organs, helping coordinate the overall response.
The tissues and organs of the immune system include more tangible parts of the body, such as the appendix, spleen, bone marrow and lymph nodes, which help produce the cells and molecules the immune system relies on.
Finally, the largest part of this complex system is the skin – our biggest organ – which acts as a physical barrier against pathogens and damage to the inside of the body.
Keeping the Immune System Strong
While we go about our daily business, our immune system is working hard to defend us. It can be weakened by illness, certain medications, being immunocompromised, or having an autoimmune condition.
On the whole, though, it can be genuinely supported by eating well, taking regular exercise, getting enough sleep, and managing stress where possible. Our guide to everyday habits that support your immune system covers this in more detail, alongside the six key vitamins worth prioritising for immune health.
