The immune system is a system of many biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.o function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue.
The cost to run for president in the general election can amount to at least $70 million USD, although the amount of money required can vary. It is possible that at some point in the future, all presidential candidates will run without taking any federal contributions.
Presidential elections to top $5 billion in donations: Fundraisers. A demonstrator rallies outside the US Chamber of Commerce against the Citizens United Jan. 21, 2015. The 2016 US presidential elections could cost as much as $5 billion, about double the cost of 2012 election, according to top fundraisers. Democratic Hillary Clinton is believed to absorb the most donations if she chooses to run for president.