The single most widely used “psychoactive” drug in America and probably the world is caffeine. Caffeine is the best friend of desperate students, determined workers and many of the greatest minds this world has known.
Why is it that we reach for a cup of joe when we feel our last vestiges of endurance flitting away?
Because caffeine improves our mood and therefore the perspective we have on the tasks at hand. It also combats the fatigue of a long day of work and enables us to gather our strength for another round of physical or mental strain. Furthermore, it clears the mind of the inconsequential and sharpens our focus to where it can make the biggest difference.
Caffeine also plays an important role in adjusting the body’s daily natural clock and is a good way to optimize routine events such as waking up, intense exercise, and mentally exhausting activities or to ward off drowsiness that occurs at the same time each day, such as when leaving work and driving home.
But there is a dark side to this providential potion; drink too much and the symptoms can be counterproductive to a clear mind and smooth operations. High doses of caffeine can result in insomnia, high blood pressure, a racing heart and profuse sweating.
So, what is it about caffeine that gives it such a unique and pleasant effect on our mind and body? It could be said that caffeine accelerates the brain’s functions by removing their braking systems. Then once you get going inertia flies you to the finish line.
It all begins with that first sip…
The second you sip that cup of coffee, black tea or energy drink, caffeine is already being absorbed into the bloodstream. Caffeine is absorbed buccally, which means it can easily traverse the linings of the mouth and throat. From here it is delivered directly into the blood where its effects on the brain and other parts of the body can be felt almost immediately.
The process begins very quickly and caffeine’s effects can last as long as 4 to 6 hours in the average human. The biggest factors that affect potency of caffeine for the individual are age, medical conditions, history of drug use and the frequency and quantity of caffeine that is consumed over time.
Caffeine in the Brain
Once in the brain caffeine plays several important roles in current brain functions, improves energy metabolism and also prevents the onset of brain deterioration in the long term. One of the most studied roles of caffeine in the brain is the way it acts as an adenosine antagonist.
Adenosine is an important time release chemical that tells the body when to initiate the wake sleep process and affects energy metabolism as well. Here’s how it works:
When adenosine is released and begins to bind to adenosine receptors, the individual begins to feel drowsy, blank and soon begins to nod off. This is the “braking system” that pulls the human body into a “rest stop” before it has a collision.
Caffeine, working as an adenosine antagonist, binds to the adenosine receptors before adenosine has a chance to do its job, essentially saying “we’ll take the next rest stop” and continue operations. This does not replace the need for proper rest but prolongs the effects of drowsiness.
This action also improves the function of dopamine, the “feel good” chemical, throughout the brain. Dopamine works better with caffeine blocking adenosine from reaching its receptors. Increased amounts of adenosine in the blood affect energy metabolism. Adrenal glands that produce extra energy react to adenosine by giving the individual a feeling of alertness and focus.
In addition to improving the energy metabolism and combating the feelings of drowsiness, lifelong caffeine consumptions, in appropriate amounts, has been found to preserve the function of the brain and resist the onset of Alzheimer’s and other cognitive conditions.
Caffeine’s Effects on the Body
Once in the bloodstream, caffeine is taken to the liver where it is metabolized into the important chemicals that can begin to affect body functions. One of these, theophylline, works to relax the smooth muscles. This is why caffeine can be used to relieve the symptoms of asthma and can increase the urgency to visit the restroom.
Caffeine also increases blood flow through the body and to the brain. More blood flow means more oxygen, more oxygen means better brain function and alertness. Initially a vasoconstrictor, caffeine begins by narrowing the blood vessels of the brain. But as the theophylline begins to take effect, the blood vessels widen and increase circulation throughout the body.
Another of these chemicals, theobromine, works to improve the assimilation of oxygen and nutrients by the muscles and brain. Which is why caffeine before routine exercise can help push limits and improves performance.
Caffeine affects many bodily functions before it is expelled from the body. These we have seen here are the most significant, but more are being researched and confirmed by the scientific and medical community every day.
Caffeine Leaves the Body
The splendid effects are short lived and within a few hours the effects of caffeine begin to wear off. This begins when the caffeine in the blood enters the kidneys and is categorically filtered out and sent to the bladder with the rest of the waste.
Caffeine is also a diuretic, which means it helps the body to release water and this action in itself help to filter the caffeine from the blood. Although, new evidence suggests caffeine has stronger diuretic effects on those who have not consumed much caffeine and have a lower tolerance to the molecule.
Once caffeine has been filtered from the blood or transformed and used by various cells, the individual can feel a sudden crash of exhaustions. This is because all the adenosine receptors that were saturated with caffeine are now open to blood flooded with adenosine.
The impulse to “pull over” for a nap is almost impossible to ignore. Dopamine is also repressed and this can make for some pretty grumpy individuals.
Hi! We’re Team NeuroGum, aficionados of all things brain-related, from creativity to working out. With backgrounds in art, science, and athletics, we love delving into all the potentials of the human body.
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How Does Caffeine Affect Energy Metabolism throughout the Brain? was originally published in Think Tank by NeuroGum on Medium, where people are continuing the conversation by highlighting and responding to this story.