Auto Defence Mechanisms

[YT2095]

after reading another thread about an injury, I got to wondering about our auto defenses against such things, some seem to be like closing the gate after the horse has bolted, for instance we get the blister After we get burned or swelling after an injury, now I`m told this is the bodies way of protecting itself against further injury, and it can`t be expected to "Predict" danger and blister 1`st.

 

but what happens when this auto defence itself becomes the life threatening factor, why doesn`t it "switch off", for example brain swelling after an injury can be fatal, even if the initial blow wasn`t, what`s the evolutionary purpose of this?

we don`t get blisters that keep expanding until they explode, and yet swelling in other parts can lead to loss of limbs or even life, surely this is counter productive?

[insane_alien]

exactly its where the defence mechanisms have gone wrong and if natural selection was still dominant in our society (medicine has almost completely negated it) then these people with faulty defence mechanisms would die out and leave us with good mechanisms.

 

E.G. caveman's brain swells up due to over active defence mechanism, he dies, genes for faulty defence mechanism are not passed on.

 

now adays, modern mans brain swells up, goes to hospital and undergoes a course of drugs and/or operations, lives, genes can be passed on.

[Royston]

E.G. caveman's brain swells up due to over active defence mechanism' date=' he dies, genes for faulty defence mechanism are not passed on.

 

now adays, modern mans brain swells up, goes to hospital and undergoes a course of drugs and/or operations, lives, genes can be passed on.[/quote']

 

We simply are not built to withstand heavy knocks due to the infrequency of them happening. Our skull is the defense we have, an incident that will penetrate / shatter the skull is rare. In fact it's only due to our modern environment that these are more frequent...car crashes et.c

 

Many animals that fight due to upholding dominance in a pack have even more protection such as antlers, horns and tusks. If our daily lives included smashing each other round the head frequently then this defense would be more highly tuned...but we don't, so there is really no need for it unless in exceptional circumstances, which isn't enough to warrant an evolutionary change.

[Primarygun]

but what happens when this auto defence itself becomes the life threatening factor, why doesn`t it "switch off"

The SARS virus speeds up our defencing system if I remember it correctly.

Really threaten the Asian

[swansont]

but what happens when this auto defence itself becomes the life threatening factor' date=' why doesn`t it "switch off", for example brain swelling after an injury can be fatal, even if the initial blow wasn`t, what`s the evolutionary purpose of this?

we don`t get blisters that keep expanding until they explode, and yet swelling in other parts can lead to loss of limbs or even life, surely this is counter productive?[/quote']

 

Consider that a defence mechanism that works most of the time is an advantage. (Think of seat belts - in most accidents, they provide safety. In rare occurrences, getting trapped in the car is bad, or getting thrown clear is an advantage.) Evolution works on populations, so if it helps 90% of the people affected, then the gene is still going to be passed along.

[Skye]

but what happens when this auto defence itself becomes the life threatening factor, why doesn`t it "switch off", for example brain swelling after an injury can be fatal, even if the initial blow wasn`t, what`s the evolutionary purpose of this?

The immune system doesn't have any decision making centre. All that the individual parts know is what they are told from other individual parts, and these interactions are pre-programmed genetically. There are only so many interactions that our genome specifies, so there are contingencies that aren't able to be adequately dealt with by the existing pathways. There's no purpose to this as such, it's a consequence of the way the system works.

[YT2095]

another question along the same lines prompted by another thread.

 

Shock, what purpose does it serve? is it a defense or protection mechanism, and if it is, how come it`s so dangerous (even fatal in some cases)?

 

isn`t it a little self defeating?

[aiza]

another question along the same lines prompted by another thread.

 

Shock' date=' what purpose does it serve? is it a defense or protection mechanism, and if it is, how come it`s so dangerous (even fatal in some cases)?

 

isn`t it a little self defeating?[/quote']

 

Yes, It could be fatal in some cases. The only true purpose of this in the first place is to protect the body from encountering something that its not suppose to have been encountered with in the first place. Our study in Immunity in school last week told us that this lines of deffense are sometimes life taking, allergies for example, Inflamation on the skin can lead to loss of function, but the bodys only intention is to put it back to homostatis, when trigered to a level that it cannot handle anymore it eventually keeps doing what its suppose to do, till it maintains balance, thus leaving this as the only down fall of our lympathic system. thats why we have antibiotics and other strong drugs to help us.... I think ((tried)