Actions and Filters

I have just started taking a closer look at WordPress development and have a question regarding actions and filters which I am curious about.

Once an action or filter have been registered (eg: add_action) then where is this actually stored? Is there perhaps a table or file some place that stores a list of currently registered hooks?

My understanding is that When a plugin is activated it registers the action or filter at that stage and then the reverse on deactivation. What puzzles me is that when someone is browsing my blog how are actions or filters triggered – there has to be someplace within WP where a table of active actions and filters are stored.

Any input, explanation or perhaps some doco that anyone could point me towards would be greatly appreciated.

R