How Does Alcohol Actually Work?

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During freshers’ week, the average student spends over £200 on booze. The ethanol found in these drinks is pretty central to almost all cultures – particularly among the young. Alcoholic drinks were brewed long before we actually understood how they work, and even now (as with the action of many drugs) some things still remain a mystery. Why, you might be wondering, as a Jesticle trickles down your throat, does this feel so great? Why, you might be wondering the next morning, do I feel so awful?

As you probably already know, the active ingredient in the sweet pacifying nectars is ethanol: a product of fermentation of sugars by yeast. No matter how good it may feel, ethanol is fundamentally a poison. If the yeast are left to keep fermenting sugars, they will eventually kill themselves from all the ethanol they produce.

ethanol
Various ways of representing Ethanol’s chemical structure. Credit: Wikimedia Commons

Ethanol is a sedative, meaning it slows down brain signals. It does this by binding to a receptor on brain cells (neurons) called GABAA, which changes the shape of the receptor. This change in shape causes the receptor to open like a gate, which allows the neuron to flood with chloride ions present outside the cell. Now that it is filled with these chloride ions, it is more difficult for electrical signals to pass through the neuron. An impossibly complicated combination of these electrical signals throughout the brain is responsible for consciousness, thought, movement and all the other functions the brain performs. Thus, our thoughts, speech and movements become sloppy as a result of these signals being slowed down. The thought processes that normally prevent us acting like a socialite, a buffoon or a flirt are diminished by this causing us to act more impulsively.

As you also may have experienced, much of a night out is often forgotten. It is thought that in order to form memories, long-term potentiation in the brain must occur. Basically what this means is that the signals between certain neurons are enhanced for an extended period of time, in response to the stimulus we are remembering. As a drug which makes signals harder to transmit, it makes sense that alcohol makes long-term potentiation more difficult. This means that, if you really go overboard, some memories simply won’t form while drunk – or at least not as clearly as when sober.

The morning after

The hangover is actually not that well understood;  there are probably multiple reasons for hangover symptoms – impurities present in drinks, a bad night’s sleep and the stomach struggling to cope. However, most symptoms are probably caused by dehydration – but how does drinking dehydrate? Alcohol inhibits the release of a hormone called ADH (anti-dieuretic hormone), which regulates urination. When high levels of ADH are present, the kidneys take in more water so less water is lost in urine. When levels of ADH are lowered, the kidneys take in less water so more of it is lost in urine. This natural cycle helps keep a healthy amount of water in the body, but alcohol disrupts it – by lowering the ADH concentration in blood, too much water is lost when peeing. The brain starts to dry and shrink a bit due to lack of water; this pulls on membranes inside the skull causing terrible headaches.

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