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The Immune System – Part 1

12 days to go

The human body is complex but when it comes to understanding how it works, the immune system is probably the most complex of all. Our immunity has been referred to a lot during the past year so I thought it would be worth a mention.

The immune system’s role is to protect us from a range of external threats including infections by bacteria or viruses, pollution we inhale, pollen or animal elements such as fur. The immune system helps deal with internal threats such as cancer and it is also a fundamental process in helping the body heal wounds after injury.

Components of the immune system are present in cells, tissues and organs. Our gut is one of the largest immune organs accounting for around 70 – 80% of immune tissue which is in the gut walls. We don’t sterilise our food and everything we consume will likely introduce something foreign to our bodies whether that be bugs, dust or otherwise. Before an invader reaches the gut it has to get past the saliva in our mouths and the acid in our stomachs. It then has to compete with billions of friendly bacteria in the gut that can deal with it.

At rest a person will inhale around 10000 litres of air a day and this can double if moderately active. The air contains many particles and gases including dust, viruses, pollen, all potentially harmful. Tiny hairs called cilia and mucus in the airways trap many of the particles and sweep them back up to be coughed out or swallowed. Any that reach the lungs may be met with specialist cells in the air sacs called macrophages which recognise the foreigners and ‘consume’ them to prevent them causing harm.

Another main organ and barrier of defence is our skin which is populated by many friendly bacteria. These play their part in dealing with unhealthy bacteria we pick up and prevent them from causing us infection.  If we sustain an injury to the skin, immune system cells in lymphatic system below the surface are activated to deal with the wound and any potential invaders.

If something does breach these external defences then it meets with the armoury of the internal immune system. Major sites are lymphatic system, tonsils, thymus gland, spleen, lymph nodes and bone marrow.

We’ll go into more detail as to how this works in part 2.





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