When we drink alcoholic drinks, the kind of alcohol we drink is called ethanol – a by-product of the fermentation process. Ethanol dissolves easily in water, so it can be rapidly absorbed from the digestive tract and circulate throughout the body in the blood. Human bodies regard ethanol as a poison, and have many defence mechanisms to try to deal with it and render it harmless. Some people find that they can drink relatively large amounts of alcohol without seeming to be drunk. This is dangerous. It could mean that they have been drinking so much that they are developing a tolerance to levels of alcohol that would have left them drunk in the past. As they drink more to experience the same level of effects, they are exposed to more and more alcohol-related harm.
Alcohol and the Liver
Alcohol circulates in the bloodstream until it is processed by the liver; the liver is where the body finishes breaking down alcohol. Working at full speed, a healthy young man's liver takes about an hour to process one drink. A healthy young woman's liver will generally take longer, which is one reason why women often become intoxicated more quickly than men and why there are different recommended upper limits for women. Put simply: if you drink faster than your liver can process alcohol, you will start to feel drunk.
Alcohol and the Brain
While alcohol is waiting to be processed by the liver it travels in the blood through the heart to all the other organs of the body, including the brain. Alcohol has traditionally been called a depressant drug because although it can make people feel "revved up" it does so by closing down different circuits in the brain. It is both a stimulant and a depressant.
At low levels, alcohol increases the electrical activity within the brain – affecting pleasure and euphoria, working in a similar way to cocaine and amphetamines. In this respect it acts like an accelerator. However, it also works on the circuits targeted by drugs such as valium – calming, easing anxiety, and acting more like a brake pedal. Alcohol also acts on the serotonin system, which (like Prozac) increases self-confidence and reduces depression.
Unfortunately this state of affairs is usually short lived. Drinking more than a couple of drinks can ruin any short-term emotional gains; taken in large amounts, alcohol interferes with some of the chemical messages in the brain. It can make the drinker clumsy, affecting coordination and slurring speech. It dramatically reduces their ability to learn and form memories, which is why people experience "blackouts." Regular drinking sessions can make it very difficult to learn new skills or retain new knowledge.
Differences between Men and Women
Women are generally affected more quickly by alcohol than are men, and the effects last longer. One reason is that they have a higher proportion of body fat and less water in their bodies: the alcohol is less diluted and therefore has a stronger affect, even if they are the same size as some men.
After stimulating the taste buds in the mouth, most of the ethanol goes into the stomach. This is where the first line of defence is found, and where the differences between men's bodies and women's bodies are the most significant. Everyone has an enzyme (alcohol dehydrogenase) in their stomach designed to process ethanol into a safer substance. For reasons that are not clear, this enzyme in men is 70-80% more effective than the same enzyme in women. There are also age differences – young women and men over 50 years of age have the most difficulty coping with alcohol. Heavy drinkers and people with alcohol problems have severely reduced levels of this important enzyme. Some women drink more when they are pre-menstrual as a way of coping with the symptoms – which is precisely when they are likely to feel the effects of alcohol most strongly.
The more time that the stomach has to work on the ethanol, the less harm it can do to your body. When a meal is eaten the exit valve of the stomach closes in order to digest the food. When food and alcohol are consumed at the same time this prevents the alcohol from passing quickly into the small intestine from where it would be rapidly absorbed giving the enzyme more time to work.