reasoning behing good germs?

[Lyudmilascience]

I don't know whether to post this in biology or anatomy.I dont know how to move it if it dosent belong here. It is also kind of a why did we evolve this way question.

 

 

Why do we need good germs for protection from bad germs? I get it if its for digestion. dont we come equiped for enough cells phagocyte cells that kills all the germs and even viruses that attack us? I learned in anatomy and physiology class that.There are already equipped with blood cells like neutrophils and macro phages they are phagocytes that squeeze out of veins. they release chemical signals to tell endothelial cells that there is an infection and those neutrophils will get stuck on to the area where the signal was sent they would eat the bacteria and die. isnt there cells in interstitial liquid and in most tissues that we dont need germs? and where do the good germs come from? how do they get on or into our body? its kind of interesting that some of the things that we need to survive like gut bacteria we dont already come equipt with. I think i need to learn more about the lymphatic system and how the cells travel through to defend the body. I couldn't find the answer to this online I found this http://www.livescience.com/32761-good-bacteria-boost-immune-system.html

 

thank you for any answers

[StringJunky]

 

Why do we need good germs for protection from bad germs?

So that we can function optimally. The beneficial bacteria physically take up the breeding/nutrient space that pathogenic species would populate... numbers matter.

 

 

. isnt there cells in interstitial liquid and in most tissues that we dont need germs?

Evolution is accidental... there is no reason.

 

 

...where do the good germs come from? how do they get on or into our body? its kind of interesting that some of the things that we need to survive like gut bacteria we dont already come equipt with

When you are born you pick up various species from the birth canal....this gives you your starting population.

 

You might find this Wiki on Vaginal Flora interesting.

[MEC1960]

The lymphatic system's primary role is to distinguish self from non-self and is only one of several lines of defense we use to combat pathogenic (disease causing) organisms. Your question revolves around the colonization of the skin and mucosa (the linings in our GI, excretory and respiratory tracts) with organisms which do not normally cause disease. These "good" germs occupy niches that "bad" germs might otherwise.

 

Our skin and mucosa are barriers to our insides - think of the space in those tracts I mentioned as the "outside"- and thus are a kind of passive immunity. This is unlike the lymphatic system which is an active form of immunity - our immune cells must undergo an active process of recognition (self v non-self), signalling to other constituents of the response, activation (and then deactivation) and then partake in various mechanisms for clearing the pathogen (the same process is used to clear cancer cells). This internal system of immunity is able to recognize and then "remember" the pathogens so that in future, should the germs breach the external barriers again, it can respond. The lymphatic immunity you refer to is called "adaptive" for this reason.

 

There are few pathogenic organisms that can cross the passive barriers themselves - usually they must be breached. A cut, tear or some other means to gain access to the "inside". We don't really need the "good" germs in this sense as our barriers are quite effective. But they are not inviolable; we are all subject to things that can damage those barriers.

 

Three features govern a germ's ability to successfully cause disease in a host; it must be be infectious (able to grow in us), pathogenic (able to cause disease) and it must be present in sufficient amount to make a beach head, so to speak. This last is called an innoculum - the number of germs- too small and it will not result in disease even if it is infectious and pathogenic (typically because our adaptive immune system clears it, but there are other passive means that can handle a small innoculum). The presence of "good" germs on our skin, for example, effectively reduces the size of the innoculum of "bad" germs on us and thus addresses one of the those three features. So having conditions which favor the growth of "good" germs can be seen as adaptive. It is likely that we have evolved to favor those conditions. They are not perfect (thus the need for an adaptive immune system) but our skin and mucosa have evolved to not just be barriers but to also provide favorable growth conditions for "good" germs.

 

I should point out that some "good" germs can turn bad. Most of us have streptococcus growing on our skin that, under normal conditions are "good", but under the right conditions can switch to being "bad".

[Ophiolite]

It becomes simpler, I think, if you consider humans to be a biosphere. Recall that there are more bacterial cells in our body than their are human cells.

[Lyudmilascience]

"There are few pathogenic organisms that can cross the passive barriers themselves - usually they must be breached. A cut, tear or some other means to gain access to the "inside". We don't really need the "good" germs in this sense as our barriers are quite effective. But they are not inviolable; we are all subject to things that can damage those barriers." i see so our bodies have barriers that keep pathogens from entering but if the barriers are broken good germs can help and the good germs can adapt and thats their advantage. you are very knolagble on this topic, fantastic answer. thank you, this answers everything