Alcohol passes down the food pipe (oesophagus) and into the stomach.

When in the stomach, 20% of the alcohol gets into your blood stream through the stomach walls.  The other 80% passes through the stomach, into the small intestines and then enters the blood stream.

The liver cleans (processes) 1 unit of alcohol out of an adult body every hour (see the 'units' section).

A young persons liver is not fully-grown and takes longer to process alcohol. Therefore, the alcohol stays in their body longer and causes more damage than it would in someone who is over 18.