Why should we bother defending ourselves? Well, we're up against some pretty nasty infective agents, just click on the pictures below and you'll see what I mean...
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So how do we defend ourselves?
Firstly, we have external barriers which organisms must try to cross, and it's not easy!!
Tears contain lysosyme, a natural antibiotic which kills bacteria. It also contains the antibiotics IgA and IgG.
Saliva contains amylase, a digestive enzyme, IgA, IgG and lactoferrin!
The sweat and sebacious secretions of the skin contain fatty acids, lactic acid and NaCl. Not many bacteria can survive these conditions.
The beating action of cilia lining the airways pushes sticky mucus upwards, together with any microorganisms which may have become trapped in it. This is known as the mucociliary escalator!
Don't forget that we also have NON-PATHOGENIC BACTERIA living in our bodies. This bacteria affords us some protection against invading micro-organisms. We have a symbiotic relationship with these bacteria, and they don't welcome intruders.... !
But what if an infectious agent slips through the net and manages to enter our bodies?
You'll need the IMMUNE SYSTEM! So here goes, get clickin'....
After you've read all that, you'll feel pretty confident about your immune system! But it can all go horribly wrong, leading to AUTO-IMMUNE DISEASES
