Re: Does caffiene have any effects on the human brain? If so, what are they?

Hi there!
	Does caffiene have any effects on the brain? Well, if you've ever drank 
a cup of strong coffee or Jolt Cola you know the answer is yes. What are 
the effects? Caffiene is a central nervous system (CNS) stimulant. It 
belongs to a class of compounds called methylxanthines. The appeal of 
coffee or soft drinks is often precisely because of this stimulant effect. 
The response is highly variable from person to person because some people 
(like me) can drink as much coffee as they like and never have any trouble 
sleeping while others can drink 1 cup and expect to toss and turn all 
night! Caffiene and similar compounds inhibit a class of enzymes known as 
cyclic nucleotide phosphodiesterases. These enzymes are, in part 
responsible for degrading a stimulatory signal produced when excitatory 
neurotransmitters activate different neurons in the CNS. Thus when they are 
inhibited by caffiene, the stimulatory signal remains active for a longer 
period of time resulting in a greater sense of alertness (a CNS effect) but 
also a higher heart rate, blood pressure and respiratory rate. Of course, 
the use of caffiene is associated with nervousness and insomnia and also 
once caffiene use is stopped, there are symptoms of withdrawal resulting 
from the chemical dependency it induces.