Immune system keeps us going

RIGHT now, I'm sitting on a tropical island off mainland Thailand and surrounded by lush flora and fascinating fauna which all looks so beautiful, you'd think you were staring into a postcard that had suddenly come alive.

I've indulged in all sorts of water sports, gourmet Asian foods, and slept in till noon every other day. But that is not the best bit so far, that is not what fills me with a deep sense of contentment right now.

You see, last time I was here, I was terribly sick and spent days in bed with a range of symptoms including fever, chills, vomiting, headaches, cramps and sore muscles.

This time, despite my careless and self-indulgent attitude, I haven't even had a hiccup! I can only assume that whatever made me sick last time I was here, has been perhaps fought off by my body in between visits and so, my immune system has rendered me much stronger to the same (or similar) germs that rendered me a mess before.

I have communicated this theory to a couple of people, both with and without medical qualifications, and they tend to agree with me. So I did some research on the human immune system.

It is truly an everyday miracle and just another reason why we shouldn't take our precious bodies and health for granted.

Every day, we are under attack from millions of germs. Most are harmless. Some can kill. Some germs only attack some parts of the body and not others. Germs' technical name is a pathogen. Pathogens attack in many forms such as bacteria, viruses, parasites and fungi.

Our first line of defence against pathogen attacks is our skin. The skin is the body's biggest organ and paradoxically, we need some 'good' germs to keep it healthy.

Did you know that we are constantly shedding skin and some bacteria that live on our skin consume some of these dead cells?

The dust in your house is almost 70 per cent human skin cells (although in Bahrain, it could equal sand as well!).

This is a slightly vulgar, yet interesting demonstration, of what is going on with your skin every single day.

Our very close second line of defense is our mucosal glands which produce mucous that can stay inside our bodies (like in our digestive tract) or venture outside (like in our nose).

Mucous helps to trap germs and either expel them or destroy them. The reason you sneeze, for example, is to expel an irritant or pathogen.

Inside our bodies, lies the third and final line of defence which resembles hard core military-style fighters in the form of different killer cells, which are both fragile and strong; complex and simple; covert and overt - it all depends on the task they are performing at the time, and the signs and symptoms the body produces.

A strong immune system depends on the nutritional biochemistry in the body at the time and how effectively the immune system responds to pathogens.

Factors such as poor diet; some drugs; stress and depression; not enough sleep; smoking; some chemicals and poor hygiene tend to override the immune system or, at the very least, make it work extremely inefficiently.

The different cells in the human immune system make for a fascinating and glorious topic for physiological research. (OK OK, I can imagine you all calling me a nerd right now...but just read on!)

The special cells that fight pathogens in your body start off as baby cells or stem cells in your bone marrow.

They develop into mature cells during a process called hematopoiesis. At the conclusion of hematopoiesis, they migrate into different areas of the body depending on the type of cells they are and what job they are going to do.

Some of these cells migrate into the thymus gland (this lies in the chest cavity).

The thymus produces mature T-cells. T-cells come in many different types and are the front line in attacking foreign and threatening cells.

These guys have the heavy artillery at their disposal to attack and destroy before the infection takes over your body. They also produce immunoglobulins - you'd know them as antibodies. When you get immunised against a disease, the doctor is actually injecting you with a weaker copy of the disease itself and it's these T-cells that build up your immunity to it by recognising the infection and sending in an army to destroy it.

If in future, you come into contact with the same pathogens as in the injection, the body is much more effective at destroying them - so much so that you probably won't even know what is going on!

Some other cells migrate into the spleen. The spleen acts as a special type of filter for the blood and captures a range of foreign materials and packs them up for elimination.

The lymph nodes are similar in terms of their filtering job. Lymph nodes can be found clumped together in your groin, armpits, and neck as well as scattered all over the body.

They drain your bodily tissues of excess fluid and any pathogens also get a free ride out of your system before they can do any damage.

If you are feeling sick and have a fever the doctor will check your lymph nodes to see if they are swollen.

If they are, it probably means they are 'overworking' to kill an infection. A fever is also an immune response. Consider that most pathogens and viruses cannot survive in cool (below 36 degrees) or hot (above 38 degrees) environments and it suddenly becomes clear why the hypothalamus in your brain turns up your internal heating system - it's aim is to kill pathogens and help your immune system do its job. Unfortunately, if your temperature is too high, it also kills off healthy cells and can impair brain function.

Fascinating huh? So, look after yourselves and know that your immune system is working 24 hours a day, seven days a week, so you can enjoy your time in the sun on a tropical island (or wherever you are at the moment). Take care everyone!