Page 26 - Veterinary Immunology, 10th Edition

An effective immune system is therefore not simply a useful system
VetBooks.ir to have around. It is essential to life itself.

The immune system can be thought of as a set of interactive
cellular and molecular networks where the presence of foreign

invaders triggers changes in cellular activities and generates an
expanding set of cellular and molecular responses that eventually
results in elimination of the invaders and increased resistance to
infection. Most of the complexity of the immune system stems from

the fact that none of its pathways are truly independent. Pathways
interact and intersect. Cells talk to each other by means of hundreds
of different signaling molecules. Microbial invasion results not in a
single response but in multiple responses involving many different

cell types producing many different molecules. Collectively, it is the
responses of these cells and molecules that keep us alive in a
microbial world.

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