Just kidding, but I do type older than I really am.

Let me explain a little more. Our bodies gather up certain raw materials and use them to make dopamine, which is then stored in tiny containers called vesicles until needed. The amount that can be made and how fast is limited by the supply of the various raw materials available. These can be things like enzymes and cofactors and mitochondrial output of the energy needed, just for an example. When your body begins to make these substances it begins to use up the materials at individual speeds. Eventually one of those materials will run out and things will grind to a halt. The substance that runs out first and triggers the shutdown is called "the rate limiting factor."

Now, consider the neurotransmitter "norepinephrine" for a moment. Norepinephrine is made much the same way as dopamine. Raw materials are gathered and norepinephrine is made. But the funny thing abut this one is that one of the things that norepinephrine is made from is dopamine!

And look at epinephrine (aka adrenaline). In a similar fashion, one of the things that epinephrine/adrenaline is made from is norepinephrine!

Now imagine this for a minute. You have just been informed by your sensory system that that guy on the bicycle is NOT going to stop. Other parts of your mind use that info and send word that you need some serious adrenaline and you need it now.

So you send the order to the adrenals and they start making adrenaline, a special hormone that is not stored but which is made fresh as needed. The raw material for that creation of adrenaline from starts pouring in to the adrenals and you note that it is mostly another hormone called "noradrenaline".

So you are mixing adrenaline as fast as you can but, then, the noradrenaline starts running low. Since you need more of that, a message goes out, "Cap'n, I don't think those entgines can handle Warp 7!" Just checking to see if everyone is still awake.

But seriously, my point is that if we have a shortage of anything then we have to prioritize and determine who gets what. And your stash of dopamine sits at the end of a chain with adrenaline at the other end.

So we have to decide on how much of our dopamine can be sent down the chain? Actually, given that the bicycle is a threat to survival, it might make sense to send it all.

My head hurts.