The medulla, or brain stem, controls or influences all of the bodily functions that you do not have to think about, 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.
For more information on the parts of the brain and their functions, see How Your Brain Works.
Alcohol's Effects on Other Body Systems
In addition to the brain, alcohol can affect other body tissues. It has the following effects on other systems in the body:
- Irritates the linings of the stomach and intestine - This can lead to vomiting.
- Increases blood flow to the stomach and intestines - This increases secretions by these organs, most notably stomach acid secretion.
- Increases blood flow to the skin - This causes a person to sweat and look flushed. The sweating causes body heat to be lost, and the person's body temperature may actually fall below normal.
- Reduces blood flow to muscles - This can lead to muscle aches, most notably when a person recovers from the alcohol (the "hangover").
All of alcohol's effects continue until the ingested alcohol is eliminated by the body.