Task One (P3)
I am under attack. You are also under attack. Everybody is. This is nothing new to us; we are under constant, ferocious, unrelenting attack from enemies that are invisible to the naked eye from our time spent as foetuses in our mother’s womb, to our dying breaths. The enormous range, diversity and number of organisms attacking us are overwhelming; they will kill us eventually, everybody must die of something, but rest assured, we will not go down without a fight.
The diverse range of threats to our wellbeing include entities such as bacteria, viruses, cancer cells, parasites and foreign cells. In order to protect ourselves our bodies have developed an enormous range of protective measures, these can be reduced to two categories: non-specific defence mechanisms and specific defence mechanisms; non-specific defence mechanisms are the first barriers to invaders, the front line of defence, as their name suggests these mechanisms are generic, fighting off anything and everything. Specific defence mechanisms are cells that have memory; once they have fought off an invading organism, the varicella zoster virus (VZV) for example, the virus responsible for chicken pox, they will remember it and should the virus attack again, even decades later, the cells will know exactly how to destroy it and will do so before the virus can get a foothold.
Non-Specific Defence Mechanisms
There are five main non-specific defence mechanisms:
1. Defence at body surfaces
3. Natural antimicrobial substances
4. Inflammatory response
5. Immunological surveillance
These mechanisms prevent entry and minimise further passage of microbes and any other foreign material to the body.
Defence at Body Surfaces
If non-specific defence mechanisms in general are the first lines of defence, the defence at body surface mechanism is the very first, its purpose is to prevent microbial invasion by using the skin and mucous membrane as a physical barrier. Healthy skin (both internal and external) is covered in a natural flora which prevents colonization by pathogens and antagonises foreign bacteria, the skin secretes sweat and sebum (an oily substance secreted by the sebaceous glands to keep the skin oily and supple), both of which contain antibacterial and antifungal substances and the skin’s dead surface layer and low pH make it difficult for foreign bacteria to survive on the skin....