Most of us will start our day in the office with a hot cup of coffee before we even consider getting around to rolling our sleeves up and digging into our emails. It is estimated that about 83 percent of adults in the U. S drink coffee. What is so addictive about this bittersweet tasting hot drink?
Coffee contains a chemical called caffeine, that can help keep us alert by changing the chemistry of the brain. When you start to feel drowsy as the day passes by this is usually caused by the binding of a chemical called adenosine to receptors in the brain. This binding slows down nerve cell activity. Adenosine is a naturally occurring chemical in the brain that we need to be able to fall to sleep, and it is produced through the day as you go about your daily business, such as being released by your muscles when you exercise.
This is where things get a little complicated. If you’re a nerve cell, caffeine really resembles adenosine, meaning that caffeine will bind to adenosine receptors. So instead of slowing the cells activity, they speed up, because the adenosine receptors on the nerve cell are taken up by caffeine and no longer can detect the adenosine that usually slows them down. This causes an increased rate at which the neurons fire off in the brain, and when the pituitary gland detects all of this increased activity, it misunderstands this as a signal that there is an emergency going on. This kicks off the “fight or flight” response, and it starts releasing hormones to signal to the adrenal glands to produce adrenaline. It’s this adrenaline that causes the tell-tale coffee side effects of a faster heartbeat, cold hands as your blood vessels constrict, and the burst of energy you get as your liver releases sugar into your blood.
So, the next time you find yourself savouring your favourite hot beverage, remember it is your adenosine receptors you have to thank for the following energy boost.
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