Caffeine Kicks In, part 1

I am going to end this week off by starting to talk about caffeine. When many people drink tea or coffee, they tend to stay awake longer. This is because caffeine is a stimulant; it makes people alert and gives them more energy.

Caffeine affects many neurotransmitters and hormones in the body. In this post, I will talk about one of them, adenosine. Adenosine is the neurotransmitter that inhibits many processes associated with wakefulness.

Adenosine levels build up throughout the day and fall rapidly when we sleep. High levels lead to sleepiness and blocking adenosine’s actions results in an increased alertness. A stimulant like caffeine blocks adenosine’s actions.

Caffeine looks like adenosine to a neuron. It works as an antagonist and binds to the adenosine receptor, as shown below. Caffeine molecules take up all of the adenosine receptors and adenosine cannot bind. It does the opposite of what adenosine does and speeds up the neuron’s electrical activity.

The effect caffeine has on the neuron is it increases the number of times the neuron fires. This causes more sympathetic nervous system activity and the pituitary gland, or “master gland,” releases hormones that prompt the release of adrenaline (I will talk about it in the next post).

This release of adrenaline results in the pupils dilating, the heart beating faster, the blood pressure rising, blood flow to the stomach slows and blood flow to the muscles increases, and the liver releases more sugar.

The next few posts will cover the effect caffeine has on other chemicals, like dopamine and adrenaline. Next week is BASIS Phoenix’s spring break and I will also be taking the week off and going out of town. So, see you all after spring break!  

~Shubhangi 

Source: Judd, Sandra J. Sleep disorders sourcebook. Detroit, MI: Omnigraphics, 2010. Print.