What is the function of the immune systems

The major function is to protect the host for environmental agents, like microbes or chemicals. Also, the immune system is to keep infectious microorganisms, like viruses and bacteria, out of the body and to destroy any infectious microorganisms that do invade the body.

not sure if this is what you'r looking for nnew= nold

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.