immune system

[sdnstud]

i never learned this in college....and am still struggling with it....is someone nice enough to give me a summary of what i need to know about immune system?

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[doanea]

Woh, that's a big one. One major points is:

Specific vs. nonspecific
Nonspecific is skin, cilia in lungs, macrophages. Everyday celanup. Granulocyte response, fever, inflammation (may continue to specific response).
Specific is the antibody immune response (humoral), raised lymphocyte count in cbc, 'memory t-cells', ect gets very complex. Think of this as the big guns of the system- powerful but takes time to activate, especially against a pathogen that isn't recognized by antibodies.

Lots more to the story though
-A

 

[bonez318ti]

I never covered it in my intro bio class either..

but here are the key concepts:

There are three phases of defense:
1) Skin, mucus membranes - impenetrable, non specific barrier against pathogens

2) Inflamatory response - non specific event that occurs when leukocytes such as Macrophages, Neutrophils, eusinophils kill off random pathogens inside your body. During an inflammatory response, say when you prick your skin, your body floods it with blood, the damaged tissues release histimines to attract the macrophages and neutrophiles (the flood of blood is why it gets red and swollen). After the macrophages and neutrophiles kill the pathogens, they themselves die (and this forms pus).

3) Immune response - this is a specific defense against specific pathogens. It gets pretty complex.. but heres the simple version (i didn't bother learning the hard one.. haha)..
first some definitions:

Antigen- Specific protein on a membrane that causes an immune response.. (so foriegn cells like bacteria, protazoa, have them, but so do human cells)..

Antibody- also called immunoglobullins (ie: iGm, iGa, IGd etc..) these are proteins that are complementary to the antigens. they bind with the antigens and agglutinate (clump), and i believe the macrophages come and phage them. by nature, our body has millions of antibodies, even complementary to antigens that may not exist. they are just floating around the body looking for their complement.

side note: the reason we express self tolerance is because when the B and T lymphocytes are developing, they are tested against 'self antigens' to make sure they wont attack it.. if they do, they are killed. Specificity is key.

B Lymphocytes - mature in the bone marrow, responsible for the humoral (blood) response by secreting loose antibodies.. so the mostly attack anything floating in the blood like bacteria (to add a level of complexity to this, the B lymphocytes actually develop (With the help of T Helper lymphocytes) into either plasma cells, which are the ones that secrete antibodies), or B memory cells..

T lymphocytes - matures in the thymus, responsible for the cell mediated response.. the key difference is that these do NOT secrete lose antibodies and the antibodies are bound to their plasma membranes. these attack mostly fixed thigns.. like cancer, tissue transplants (these also develop into two diferent types, analogous to the B.. except rather than plasma, they are cytotoxic T lymphocytes and T memory cells)

B&T memory cells - these are responsible for the 2ndary immune response.. so after you get sick once, the memory cells develop and remain in your body so that they are on the look out and ready to attack should these same antigen attack your body in the future.

Ok.. so to tie it all together- When a pathogen first invades the body, the body has never had exposure to the specific antigen.. so it has to wait until an antibody that is complementary binds to it. once it binds to it, it sets off the immune response. other B and T lymphocytes with this same antibody are replicated, and it mounts an attack against the pathogen. this is the primary immune response.
the next time the same pathogen arrives, the memory cells will be ready to attack, and can ramp up alot faster to mount an attack against the pathogen. so remember that the secondary immune response is alot faster and stronger than the primary response.

oh yea.. you should definitely have an understanding of how this applies to blood types:
Type A - has type A antigens, so it doesnt have type A antibodies otherwise it would attack itself. rather it has type B antibodies.
Type B - has type B antigens, and type A antibodies
Type AB - has type AB antigen, and no antibodies (unversal receiver of blood)
Type O - has neither antigen, and both types of antibodies (unversal donor)

 

[OHare]

oh yea.. you should definitely have an understanding of how this applies to blood types:
Type A - has type A antigens, so it doesnt have type A antibodies otherwise it would attack itself. rather it has type B antibodies.
Type B - has type B antigens, and type A antibodies
Type AB - has type AB antigen, and no antibodies (unversal receiver of blood)
Type O - has neither antigen, and both types of antibodies (unversal donor))

Are you sure type O has both antibodies? Then it couldn't be a donor because it would attack any other blood type it was donated to other than O. I know it LACKS both antiGENS.

 

[Monkey12]

Are you sure type O has both antibodies? Then it couldn't be a donor because it would attack any other blood type it was donated to other than O. I know it LACKS both antiGENS.

In the past, people with Type O/Rh-negative blood were considered universal blood donors ? because their red blood cells had neither AB or Rh antigens. This implied that anyone, regardless of blood type, could get Type O/Rh-negative blood without having a transfusion reaction.

But scientists now have a much better understanding of the complex issues related to reactions to incompatible donor blood cells. Even donors with Type O/Rh-negative blood may have other antibodies that cause serious reactions.