Your Body: How Alcohol Gets You Drunk

Although I’ve been asked this question quite a few times, this specific post was requested on Facebook by the lovely Vicky!

 

Most of us have had an alcoholic drink in our time. Most of us, then, will know that alcohol affects the way we feel, the way we react, and our ability to do certain things, like resist fried potatoes. Most of us will probably also have noticed that alcohol affects people slightly differently, personally I become very giggly and inane, and then I go to sleep. I know people who become very angry or upset. I know other people who just can’t stop dancing (okay, so that one might be me as well). It all depends on the person, the amount of alcohol, they’ve drunk, and often how they felt to begin with. This post can’t explain how individuals react to alcohol, but it will explain how alcohol enters your body, and some of the things it gets up to in your brain.

Alcohol, then. Whether it’s gin, vodka, whiskey, wine, beer, or any other tipple of your choice, when we refer to alcohol in drinks, what we actually mean is ethanol, alcohol itself being the chemical term to describe any compound with an alcohol group, an –OH attached to a carbon atom, attached. As a result I’m probably going to try and get the phrase ‘ethanolic beverage’ to catch on in my everyday life. Just because.

Ethanol on a t-shirt. Molecules on t-shirts are ALWAYS cool.
Image credit.

When you drink alcohol, roughly 20% is absorbed straight from your stomach into your bloodstream. The other 80% is taken up from your small intestine. This explains why eating before you drink can slow down the effects of alcohol, if your tummy is full of food, it’s harder for the alcohol to end up by the stomach walls, where it can be absorbed. It’s also why drinking on an empty stomach can have such a speedy effect, 20% of the alcohol gets STRAIGHT into your bloodstream, and straight to work.

And how DOES it work? Well, in short it tries to sloooooow your brain down. Nerve cells in your brain, and indeed in your arms and legs and everywhere else you’ve got nerves, pass messages along themselves via action potentials. However, action potentials can’t simply leap from one nerve cell to another, when they reach the end of a nerve cell they need a go-between. These go-betweens, these molecular messengers, are neurotransmitters.  When an action potential arrives at the end of the nerve, the synapse, this triggers a flood of neurotransmitter molecules to be released, like a hoard of tiny very very efficient postmen, delivering messages to the nearby nerve cells. These messages can either be excitatory, like a REALLY COOL party invitation, or the arrival of a book you’ve been waiting for (what? To me that’s exciting, okay?), or they can be inhibitory, like bills and junk mail. The difference is that your nerve cells have different post boxes for different types of messages; they have specific receptors for each neurotransmitter.

When alcohol is in your brain, it sneakily PRETENDS to be a postman; it binds to the receptors that usually receive messages from neurotransmitters. Broadly speaking, if it binds to a receptor that usually receives exciting messages and gets motivated and gets things done, then it inhibits it; it blocks the getting-things-done messages. If it binds to a receptor that usually slows things down, however, it simply encourages it to slow things down even further. Alcohol just wants your brain to live life at a slower pace.

The actual effects that you feel alcohol having depends on which part of the brain is being slowed down, and of course the more alcohol you have in your blood, the more areas of the brain it can get to. It usually starts in the cerebral cortex, which is the region of your brain mainly responsible for cognitive thinking, behaviour, and voluntary muscle movements. Slowing things down here means your brain processes information that it receives more slowly, this might mean you feel less sensitive to touch, or to pain. It’s a trick, of course, your body still receives the damage, your brain just doesn’t process the information as pain quite so quickly, so you don’t realise. Your cerebral cortex also contains the region of the brain that controls your behaviour, alcohol slowing things down in this area suppresses some of that control; you lose some of your inhibitions, and you start to lose the ability to know what is appropriate behaviour.

Another area on alcohol’s fake postman delivery rounds is the limbic system, where it affects your ability to control your emotions. This is presumably why alcohol often feels like it exaggerates any emotion you were feeling before you started drinking, whether that was happy, angry or really sad. Alcohol also affects the cerebellum, the art of your brain that co-ordinates muscle movement. The cerebellum is movement HQ, it organises messages to and from all your muscles, to that they can perform together, in beautiful harmony, allowing you to complete fiddly motor tasks like touching your nose, or walking in a straight line. The more alcohol depresses activity in this area, the less co-ordinated you become, until eventually you can’t co-ordinate enough to even stand up.

Finally, alcohol gets to work in your hypothalamus and pituitary gland, where it mainly stops the production of anti-diuretic hormone (ADH). ADH is what tells your kidneys to conserve water, and without it, you simply get rid of more and more, resulting in a need to have a wee REALLY often. The more alcohol in your bloodstream, the more areas of your brain it can reach, until eventually it affects your medulla, the centre responsible for keeping you doing things you do without thinking, alcohol slowing things down here makes you sleepy, and eventually you lose conciousness.

So that’s how alcohol affects your body, it heads to your brain, mimics your molecular postmen, and in doing so inhibits your ability to do lots of things you can normally do perfectly well, like stand up straight, not cry in public, and know when it is appropriate to shake your booty.

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6 thoughts on “Your Body: How Alcohol Gets You Drunk

  1. Pingback: Your Body: How Alcohol Gets You Drunk | Science Communication Blog Network

  2. Pingback: The Week in Science (Feb 11-17) | Science Communication Blog Network

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