How Alcohol Works

为了理解酒精对波的影响dy, it is helpful to understand the nature of alcohol as a chemical, so let's take a look.

Here are several facts:

Alcohol can be made by three different methods:

The type of alcohol found in alcoholic beverages is ethyl alcohol or ethanol. Themolecular structure of ethanolis C2H6O. It can also be written as CH3CH2OH or C2H5OH.

In this structure,Cis carbon,His hydrogen,Ois oxygen. The OH (O-H) group on the molecule is what gives it the specific chemical properties of an alcohol. For the remainder of this article, when we say "alcohol," we mean ethanol.

You will not find pure alcohol in most drinks; drinking pure alcohol can be deadly because it only takes a few ounces of pure alcohol to quickly raise the blood alcohol level into the danger zone. For various types of beverages, the ethanol concentration (by volume) is as follows:

In the United States, you must be 21 years or older to buy alcoholic beverages, and there are penalties for serving or selling alcoholic beverages to minors.

When a person drinks an alcoholic beverage, about20 percent of the alcohol is absorbed in the stomachand about 80 percent is absorbed in the small intestine. How fast the alcohol is absorbed depends upon several things:

After absorption, the alcohol enters the bloodstream and dissolves in the water of the blood. The blood carries the alcohol throughout the body. The alcohol from the blood then enters and dissolves in the water inside each tissue of the body (exceptfat tissue, as alcohol cannot dissolve in fat). Once inside the tissues, alcohol exerts its effects on the body. The observed effects depend directly on the blood alcohol concentration(BAC), which is related to the amount of alcohol the person has consumed. A person's BAC can rise significantly within 20 minutes after having a drink.

Once alcohol is absorbed into a person's bloodstream, it leaves the body in three ways:

As a rule of thumb, an average person can eliminate 0.5 ounces (15 ml) of alcohol per hour. So, it would take approximately one hour to eliminate the alcohol from a 12 ounce (355 ml) can of beer.

The BAC increases when the body absorbs alcohol faster than it can eliminate it. So, because the body can only eliminate about one dose of alcohol per hour, drinking several drinks in an hour will increase your BAC much more than having one drink over a period of an hour or more.

The breakdown, or oxidation, of ethanol occurs in the liver. An enzyme in the liver calledalcohol dehydrogenasestrips electrons from ethanol to form acetaldehyde. Another enzyme, calledaldehyde dehydrogenase, converts the acetaldehyde, in the presence of oxygen, to acetic acid, the main component in vinegar. The molecular structure of acetic acid looks like this: CH3COOH.

When ethanol is oxidized to acetic acid, two protons and two electrons are also produced. The acetic acid can be used to form fatty acids or can be further broken down into carbon dioxide and water.

If you have seen someone who has had too much to drink, you've probably noticed definite changes in that person's performance and behavior. The body responds to alcohol in stages, which correspond to an increase in blood alcohol concentration.

Blood alcohol concentration (BAC) refers to the percent of alcohol in a person's blood stream. A BAC of .10 percent means that an person's blood supply contains one part alcohol for every 1,000 parts blood. As we already mentioned, several affect BAC, including body weight, biological sex, how many drinks the person has consumed (and how fast), medications and more. But the body responds to the level of alcohol in the blood, too:

Euphoria(BAC = 0.03 to 0.12 percent)

Excitement(BAC = 0.09 to 0.25 percent)

Confusion(BAC = 0.18 to 0.30 percent)

Stupor(BAC = 0.25 to 0.4 percent)

Coma(BAC = 0.35 to 0.50 percent)

Death(BAC more than 0.50 percent)

Alcohol acts primarily on the nerve cells within thebrain. Alcohol interferes with communication between nerve cells and all other cells, suppressing the activities of excitatory nerve pathways and increasing the activities of inhibitory nerve pathways.

For example,University of Chicago Medical Center: Alcohol and Anesthetic Actionstalks about the ability of alcohol (and inhaledanesthetics) to enhance the effects of the neurotransmitter GABA, which is aninhibitoryneurotransmitter. Enhancing an inhibitor generally induces sluggishness, which matches the behavior you see in a drunk person. Alcohol not only enhances an inhibitor, it also weakens anexcitatoryneurotransmitter called glutamine. Dampening the effect of an excitatory neurotransmitter also produces sluggishness. Alcohol does this by interacting with the receptors on the receiving cells in these pathways.

Alcohol affects various centers in the brain, both higher and lower order. The centers are not equally affected by the same BAC — the higher-order centers are more sensitive than the lower-order centers. As the BAC increases, more and more centers of the brain are affected.

The order in which alcohol affects the various brain centers is as follows:

The cerebral cortex is the highest portion of the brain. The cortex processes information from your senses, does your "thought" processing and consciousness (in combination with a structure called the basal ganglia), initiates most voluntary muscle movements and influences lower-order brain centers. In the cortex, alcohol does the following:

These effects get more pronounced as the BAC increases.

的大脑区域的边缘系统由called the hippocampus and septal area. The limbic system controls emotions and memory. As alcohol affects this system, the person is subject to exaggerated states of emotion (anger, aggressiveness, withdrawal) and memory loss.

The cerebellum coordinates the movement of muscles. The brain impulses that initiate muscle movement originate in the motor centers of the cerebral cortex and travel through the medulla and spinal cord to the muscles. As the nerve signals pass through the medulla, they are influenced by nerve impulses from the cerebellum. The cerebellum controls fine movements. For example, you can normally touch your finger to your nose in one smooth motion with your eyes closed; if your cerebellum were not functioning, the motion would be extremely shaky or jerky. As alcohol affects the cerebellum, muscle movements become uncoordinated.

In addition to coordinating voluntary muscle movements, the cerebellum also coordinates the fine muscle movements involved in maintaining your balance. So, as alcohol affects the cerebellum, a person may lose their balance frequently. At this stage, this person might be described as "falling down drunk."

The hypothalamus is an area of the brain that controls and influences many automatic functions of the brain through actions on the medulla, and coordinates many chemical or endocrine functions (secretions of sex, thyroid and growth hormones) through chemical and nerve impulse actions on thepituitary gland. Alcohol has two noticeable effects on the hypothalamus and pituitary gland, which influence sexual behavior and urinary excretion.

Alcohol depresses the nerve centers in the hypothalamus that control sexual arousal and performance. As BAC increases, sexual behavior increases, but sexual performance declines.

Excessive drinking also inhibits the pituitary secretion of anti-diuretic hormone(ADH), which acts on the kidney to reabsorb water. Alcohol acts on the hypothalamus/pituitary to reduce the circulating levels of ADH. When ADH levels drop, the kidneys do not reabsorb as much water; consequently, the kidneys produce more urine.

The medulla, or brain stem, controls or influences all of the bodily functions that are involuntary, like breathing, heart rate, temperature and consciousness. As alcohol starts to influence upper centers in the medulla, such as the reticular formation, a person will start to feel sleepy and may eventually become unconscious as BAC increases. If the BAC gets high enough to influence the breathing, heart rate and temperature centers, a person will breathe slowly or stop breathing altogether, and both blood pressure and body temperature will fall. These conditions can be fatal.

In addition to the brain, alcohol can affect other bodily functions, including the following:

All of alcohol's effects continue until the ingested alcohol is eliminated by the body.

Globally an estimated 237 million men and 46 million women have some form of alcohol-use disorder, that's according toWHO's 2018 Global status report on alcohol and health.

In the United States, approximately 15.1 million adults ages 18 and older (6.2 percent of this age group) hadalcohol use disorder (AUD),这是一种慢性复发性脑疾病,在吗volves the affected person compulsively using alcohol, losing control over their alcohol intake, and having a negative emotional state when they're not drinking. This includes 9.8 million men. In 2010, alcohol misusecost the U.S. $249 billion.

Research has shownthat alcohol use in general has risen in recent years, andproblem drinking(which includes alcohol abuse, i.e. drinking to the point where it causes recurrent and significant life problems, and alcohol dependence, i.e. the inability to stop drinking) has risen by a greater percentage, particularly in women, racial minorities, older adults, and lower socioeconomic classes. With the continued exposure to alcohol, how does the human body respond or adapt? The body's increased tolerance to alcohol involves the following changes:

These bodily adaptations change a person's behavior. The levels of alcohol dehydrogenase and aldehyde dehydrogenase in the liver increase in response to long-term alcohol exposure. This means that the body becomes more efficient at eliminating the high levels of alcohol in the blood. However, it also means that the person must drink more alcohol to experience the same effects as before, which leads to more drinking and contributes toaddiction.

The normal chemical and electrical functions ofnerve cellsincrease to compensate for the inhibitory effects of alcohol exposure. This increased nerve activity helps people to function normally with higher BAC; however, it also makes them irritable when they are not drinking. Furthermore, the increased nerve activity may make them crave alcohol. Most certainly, the increased nerve activity contributes to hallucinations and convulsions (e.g. delirium tremens) when alcohol is withdrawn, and makes it difficult to overcome alcohol abuse and dependence.

In addition to the adaptations mentioned on the previous page, there are many adverse physical effects that result from long-term exposure to alcohol:

Finally, alcohol abuse and dependence cause emotional and social problems. Because alcohol affects emotional centers in the limbic system,alcoholicscan become anxious, depressed, and evensuicidal. The emotional and physical effects of alcohol can contribute to marital and family problems, including domestic violence, as well as work-related problems, such as excessive absences and poor performance.

While alcoholism has devastating effects on a person's health and social environment, there are medical and psychological ways to treat the problem. See the next page to learn more.

For more information on alcohol, treating alcoholism, and related topics, check out the links on the next page.