What is the immediate effect of alcohol on the various body organs and functions?
As already noted, alcohol is an irritant, which explains the burning sensation as it goes down. Alcohol in the stomach promotes the flow of gastric juices. A glass of wine before dinner may thereby promote digestion by "priming" the stomach for food. But with intoxicating amounts, alcohol impedes or stops digestion.
Alcohol has only minor effects on the circulatory system. Heartbeat and blood pressure are little affected. In moderate amounts, alcohol is a vasodilator of the surface blood vessels. These vessels expand near the skin surface, which accounts for the sensation of warmth and a flush to the skin that accompanies drinking. Despite the feeling of warmth, body heat is being lost. Thus whoever sends out the St. Bernard with a brandy cask to the aid of the snow-stranded traveler is misguided. Despite the illusion of warmth, a good belt of alcohol will likely further cool off the body.