Re: chemicals reactions stimulate all feelings,thoughts and actions.why and how

Dear Eoin,

A little problem with your question is that it is very large. Chemical 
reactions in the body are numerous, so are feelings, thoughts and actions. 
The body is composed of several kinds of cells (ex. skin cells, heart cells 
etc...). Neurons are particular cells because they are excitable; they 
can produce action potentials that send information to more distant 
neurons. This implies chemical reactions. Neurons form the nervous system 
(brain, spinal chord and peripheral nerves). Actually, a neuron is just 
like an electrical wire: it can be short or long and, more important, it 
sends information to other neurons. One peculiarity of neurons is that 
they do not touch each other; they are separated by a very thin space 
called a synapse. Most neurons communicate between each other via a chemical 
agent (neurotransmitter) which is released in the synapse by a neuron and 
captured by another neuron. The latter can be excited or inhibited by the 
neurotransmitter. Although this process' duration is about a millisecond, 
it implies many chemical reactions. Moreover, certain kinds of neurons 
release their chemical agent in the blood and can therefore act on many 
distant cells. A particular chemical agent can also be specific: it may 
affect only certain kind of cells while having less or no effect on 
others. It can be proposed that a given emotion, thought or action is 
experienced when specific sets of neurons are excited. 

One thing that should be remembered is that chemical reactions in the 
brain are various and numerous. It is true that they subtend many aspects 
of our experience but they take place in a very organized network of 
neurons and other cells. The more you understand the network (ex. 
connectivity of neurons, their morphology, the transmitters they use and 
those which can stimulate them), the more you can postulate hypotheses 
about how our feelings, thought and actions are produced.

Hope that helps,
Eric