The effects of alcohol on the human body can take several forms.
Alcohol, specifically ethanol, is a potent central nervous system depressant, with a range of side effects. The amount and circumstances of consumption play a large part in determining the extent of intoxication; e.g., consuming alcohol after a heavy meal is less likely to produce visible signs of intoxication than consumption on an empty stomach. Hydration also plays a role, especially in determining the extent of hangovers. The concentration of alcohol in blood is usually measured in terms of the blood alcohol content.
Alcohol has a biphasic effect on the body, which is to say that its effects change over time. Initially, alcohol generally produces feelings of relaxation and cheerfulness, but further consumption can lead to blurred vision and coordination problems. Cell membranes are highly permeable to alcohol, so once alcohol is in the bloodstream it can diffuse into nearly every biological tissue of the body. After excessive drinking, unconsciousness can occur and extreme levels of consumption can lead to alcohol poisoning and death (a concentration in the blood stream of 0.55% will kill half of those affected). Death can also be caused by asphyxiation when vomit, a frequent result of over-consumption, blocks the trachea and the individual is too inebriated to respond. An appropriate first aid response to an unconscious, drunken person is to place them in the recovery position.
Intoxication frequently leads to a lowering of one's inhibitions, and intoxicated people will do things they would not do while sober, often ignoring social, moral, and legal considerations
This article primarily covers the short-term effects of alcohol on the adult human body. For the potential long-term cumulative effects of alcohol on the adult human body, please refer to alcohol consumption and health, alcohol and cardiovascular disease, alcohol and cancer, alcohol and weight and alcoholic liver disease. The potential impact of alcohol consumption by pregnant women on their fetuses is discussed in the article fetal alcohol syndrome.
Metabolism of alcohol and action on the liver:
The liver breaks down alcohols into acetaldehyde by the enzyme alcohol dehydrogenase, and then into acetic acid by the enzyme acetaldehyde dehydrogenase. Next, the acetate is converted into fats or carbon dioxide and water. The fats are mostly deposited locally which, according to some,leads to the characteristic "beer belly". Chronic drinkers, however, so tax this metabolic pathway that things go awry: fatty acids build up as plaques in the capillaries around liver cells and those cells begin to die, which leads to the liver disease cirrhosis. The liver is part of the body's filtration system which, if damaged, allows certain toxins to build up, leading to symptoms of jaundice.
The alcohol dehydrogenase of women is less effective than that of men. The percentage of water in women's bodies is less than that of men. Therefore, the alcohol has less volume to dissolve in, leading to a higher blood alcohol concentration when the same amount of alcohol is ingested. This contributes to the fact that women become intoxicated more quickly than men. Also contributing is the fact that men have a more active first-pass metabolism of alcohol in the stomach and small intestine.
Some people's DNA code for a different acetaldehyde dehydrogenase, resulting in more potent alcohol dehydrogenase. This leads to a buildup of acetaldehyde after alcohol consumption, causing the alcohol flush reaction with hangover-like symptoms such as flushing, nausea, and dizziness. These people are unable to drink much alcohol before feeling sick, and are therefore less susceptible to alcoholism.This adverse reaction can be artificially reproduced by drugs such as disulfiram, which are used to treat chronic alcoholism by inducing an acute sensitivity to alcohol.
Dehydration:
Overconsumption can therefore lead to dehydration (the loss of water )
Hangover:
A common after-effect of ethanol intoxication is the unpleasant sensation known as hangover, which is partly due to the dehydrating effect of ethanol. Hangover symptoms include dry mouth, headache, nausea, and sensitivity to light and noise. These symptoms are partly due to the toxic acetaldehyde produced from alcohol by alcohol dehydrogenase, and partly due to general dehydration. The dehydration portion of the hangover effect can be mitigated by drinking plenty of water between and after alcoholic drinks. Other components of the hangover are thought to come from the various other chemicals in an alcoholic drink, such as the tannins in red wine, and the results of various metabolic processes of alcohol in the body, but few scientific studies have attempted to verify this. Consuming water between drinks and before bed is the best way to prevent or lessen the effects of a hangover. The severity of hangover depends on the effects of the byproducts of the fermentation process that brings out the taste and aroma of the beverage, also known as congeners. With more congeners, the chance of a severe hangover increases. Brandy has the largest amount of congeners, followed by red wine, rum, whiskey, white wine, gin and vodka.
