Alcohol and the human body

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• Why does alcohol change behaviour?

Numbing effects

As your blood-alcohol level rises, your brain’s motor and sensory centres are affected. You begin to have difficulty with coordination and fine motor functions, and your reaction time slows.

The effects can be minor or major, depending on how much you drink. If you have a blood-alcohol level of .08, or 80 mg of alcohol per 100 ml of blood – the legal limit for driving a motor vehicle in Canada – your reaction time will be 30% 50% slower than when you have no alcohol in your blood. For example, driving under the influence of alcohol will make it difficult to brake quickly if the car ahead stops suddenly.

As you become intoxicated, your speech, thought processes and senses are affected. Your cognitive and verbal skills are diminished; and since these are the skills that allow you to resolve conflicts, there is a greater likelihood of aggressive and violent behaviour.
The part of the brain that controls vomiting is affected by the alcohol and toxic acetaldehyde circulating in your blood.
Alcohol also affects the pituitary gland, resulting in reduced secretions of the anti-diuretic hormone that maintains the body’s proper hydration level. More specifically, the kidneys are no longer able to reabsorb sufficient water from your urine, and your body ends up eliminating more water than it absorbs. The symptoms of dehydration are fatigue, back and neck pain, and headaches.

The immediate effects on the brain are often less apparent among people who drink regularly, because they have developed a strong tolerance for alcohol. As a result, they can often drink a great deal without feeling too many short-term effects. Such tolerance is both metabolic – the liver processes the alcohol more quickly and efficiently – and functional – the person learns to compensate for the deficits caused by alcohol.

Nevertheless, the harmful effects of drinking will be seen and felt in the long term. In fact, people whose bodies are habituated to the immediate effects of alcohol are generally those who drink abusively.

How does alcohol affect other vital organs?

Heart and cardiovascular system

Just one or two drinks can affect your heart rate, blood pressure, circulation and contractions of the heart muscle, including its ability to pump blood through your body. While these reactions are generally not considered significant from a clinical point of view, they can be more serious if you already suffer from cardiovascular problems.

Among other things, alcohol causes the small blood vessels beneath the skin to dilate, which increases blood circulation. You may have noticed that some heavy drinkers have a particularly ruddy complexion. What you’re seeing is the result of the dilated blood vessels.

The dilation of blood vessels also causes heat loss, and a drop in body temperature. Contrary to popular belief, it is very dangerous to drink alcohol to “warm up” when you are exposed to the cold.

As soon as even a small amount of alcohol is ingested, the intestines begin to secrete acid. As the blood-alcohol level rises, secretions of pepsin, a digestive hormone, are reduced, leading to an irritation of the intestinal walls and eventually diarrhea.
The pancreas produces insulin, which the body needs to control blood sugar levels. Drinking causes a sudden spike in blood sugar; the pancreas responds by producing more insulin. This causes a rapid drop in blood sugar and the symptoms of hypoglycaemia – dizziness, headaches, difficulty concentrating, depression, anxiety, trembling, cold sweats, heart palpitations, loss of coordination, and stomach aches.
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