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stevo247

The Immune System

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Do all living organisms have some form of an immune system? I was thinking that the cell membrane itself, may represent the most primitive form of an immune system. Comments?

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It depends how you're defining 'immune system.' Because it sounds like you're presenting a semantics argument.

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“The waxy cuticle of many leaves, the exoskeleton of insects, the shells and membranes of externally deposited eggs, and skin are examples of the mechanical barriers that are the first line of defense against infection.”

http://en.wikipedia.org/wiki/Immune_system

 

Doesn't a cell membrane serve the exact same function?

 

 

 

“Even simple unicellular organisms such as bacteria possess enzyme systems that protect against viral infections.”

http://en.wikipedia.org/wiki/Immune_system

 

 

From the biology on-line dictionary. Immune system:

“A system that provides a defense mechanism to organism, providing defensive measures against antigens which would prove harmful to the organism.”

 

So is it safe to say that all living organisms have some form of an immune system?

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In regards to something like an amoeba, I would think that a good way to fight an enemy would be to eat it.

 

 

Is there a relationship between the immune system and “eating”?

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In regards to something like an amoeba, I would think that a good way to fight an enemy would be to eat it.

 

 

Is there a relationship between the immune system and “eating”?

 

lol nah, not if you mean predators. Immune system is protection against pathogens and foreign bodies.

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I just have a rough working definition of an immune system and it is crude and simple, but it would involve a cellular or non cellular attack against forign antigens. Therefore, if the cell membrane was capable of launching such an attack then it must be included. However cells of many body tissues do not appear to launch an attack on foreign bodies. So I would guess that the cell membrane is not part of an immune system response.:cool:

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"Many of us grew up marveling at the amoeba's abundance in pond water; if you look at amoebas under a high-power lens, you can see them wandering around on the slide, but you will also see that they are feeding on micro-organisms, just like a culture of macrophages. It seems as if the amoeba is the earliest form of macrophage, and perhaps gave rise, by an unknown evolutionary pathway, to the modern macrophage. Innate immunity in eukaryotes can be thought of as arising from the need of a unicellular microorganism such as an amoeba to discriminate between food and other amoebas. If you think about it, any amoeba that could not make this distinction would be bound to consume itself and vanish from the face of the Earth. Therefore, we can infer a specific surface receptor on amoebas that acts to discriminate between food, which can eagerly be engulfed, from what is another amoeba, or even another part of the same amoeba. The nature of this presumed receptor is not yet known, but it must be highly specific and must discriminate self from nonself, which is one of the most basic functions of the immune system."

 

 

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=imm.section.2367

 

Macrophage means "big eater". Macrophages are white blood cells that crawl around in the extracellular fluids of your body and gobble up microbes and other foreign material. They ingest these microbes by phagocytosis ("cell eating"). Parts of the cell surround the particle to be eaten, then the macrophage's membrane flows together and the particle ends up inside.

http://www5.pbrc.hawaii.edu/microangela/macroph.htm

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Well, it appears that by "immune system" you mean defenses against viruses, diseases, etc. Everything living has this type of defense built into their cells - the cell membrane is basic protection and filters out harmful products. But this isn't great protection, because viruses are almost always able to get through the tiny pores.

 

So if you mean an advanced adaptive immune system, like the specialized white blood cells that lock down viruses with antigens, macrophages to dispose of them, and B-Cells to memorize the viruses in order to create new antigens, it'd really only be animals that would have this type of defense. Compared to other organisms, the complexity makes it necessary.

 

However, all animals and plants also have an "innate immune system." I don't know too much about it, but this basically means that the organism responds to any disease in the same way (this occurs when an adaptive immune system meets something new. Then it adapts.) This response is primitive, but works well enough.

 

So yes, everything that is alive has its own immune system. Now I'm surprised that you actually read all that.

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Thinking what you said. Single cellular organisms have their own lines of defense. Multicellular sort of takes defense away from most of the individual cells, and gives the responsibility to a group of specialty cells. It sort of an odd design in the sense, two lines of defense would make more sense. In terms of military strategy, we put the best troops of the immune system, as the front line doing most of the work. We also have a secondary force with each cell able to handle low level assault. This would seem more air tight.

 

The question I asked is, if the current system is more evolved there must be something about it that makes it a more efficient system or a system that is more conducive to evolution. Did anyone ever consider that maybe some virus and the like are suppose to get through. There is nothing to say that virus can't have the opposite affect of sickness. I was thinking about the excellent immune system of sharks and how they never seem to change over a long time. They may be too tight which is good for them but not as conducive to change.

 

The other half had to do with efficiency. This had to indirectly do with the power of positive thinking. Does the nervous system play a role in directing the immune system? I look at it this way. Nerve cells are smart tissue and the macrophages are smart in their own autonomous way. The nerve tissue near a cell is monitoring the environment. When you get an invasion, the water near the cell changes the nerve sounds the alarm. It would explain, at some level, how things know where to go. It is not Keystones Cops, but seems more directed.

 

When you cut you finger one can feel the sensory signal and almost immediately the troops are deployed. This gets our attention sort of focusing the mind-brain on the cut-pain. The dog licking the cut is also stimulating nerves. Is there a correlation between the brain-nervous system complexity and immune system complexity?

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Is there a correlation between the brain-nervous system complexity and immune system complexity?

 

That's a good question. I was also wondering if the immune system and the nervous system are the only systems that have "memory".

 

If the immune system predates the brain, is the brain a part of the immune system? Maybe the immune system is the defense against microbes, and the brain is the defense against "lions and tigers and bears".

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Well, macrophages and neutrophils eat pathogens and they are key players of the immune system.

 

An immune system is any type of mechanism or structure that defends against pathogens.

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Although not technically an immunological response to an invading pathogen many organisms have either native intracellular mechanisms or secreted extracellular ones. Whether this extends to plants I don't know but I wouldn't be surprised if they do have an evolved immune response mechanism.

 

For instance; one of the key tools in molecular biology, restriction endonucleases are derived from bacteria as a line of defense against invading phages. Additionally there is the non-specific antimicrobial lysozyme secreted in saliva and chicken egg white. Seeing how lysozyme is prevalent throughout the animal kingdom I would not be surprised if it is a primitive form of innate immunity. As for adaptive immunity I expect that it is a later addition to complex multicellular life.

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The alternative & lecthin pathways of the complement cascade, serum proteins that are cleaved sequentially & can lyse foreign particles, are found even in invertebrates. They are not, however, seen in yeast.

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An immune system is any type of mechanism or structure that defends against pathogens.

 

Actually it is just a means to get rid of foreign elements. They do not have to be harmful per se to be a target of an immune system. It is kind of a means between self and non-self (and to attack the latter).

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There are bacteria that live in the gut, for example, which are useful. How does the immune system determine friend from enemy?

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Gut is an external sphere of our body, so there is no need to recognize everything that's in it as self and non-self.

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