Coffee is a universal drink with a worldwide consumption of about 10 to 13 billion lbs. per year. About eight in 10 Americans drink coffee, and many people depend on it to wake them up every morning. While coffee is rich in antioxidants, contains fiber and has numerous health benefits, it is mainly consumed because it increases your general feeling of well-being. The caffeine in coffee stimulates the central nervous system, decreasing drowsiness and increasing mental alertness.
Caffeine in a Cup of Coffee
According to MayoClinic.com, the amount of caffeine in a cup of coffee varies and depends on roasting and grinding of the coffee beans, as well as the brew time. A 16-oz. cup of brewed coffee from a coffee shop contains 143 to 206 mg of caffeine, while a 1-oz. espresso contains 58 to 75 mg of caffeine. Some other caffeine-containing products are tea, soft drinks, sports and energy drinks and chocolates. On an average, an American has a daily consumption of 280 mg of caffeine from all sources.
Absorption of Caffeine
The effects of coffee are felt soon after you drink it. This is because the caffeine in coffee does not need digestion but is absorbed in the stomach and small intestine. Caffeine then enters the bloodstream and reaches different parts of the body. In the brain, caffeine is effective in reducing tiredness and sleepiness for a short time. Caffeine is excreted in urine several hours after consumption.
Central Nervous System Effects
The brain and spinal cord make up the central nervous system, which is responsible for relaying external and internal signals to and from the brain. The caffeine in coffee is a chemical that affects the activity and function of the central nervous system. Because of its action in enhancing alertness, caffeine is often referred to as a central nervous system stimulant.
Caffeine as a Stimulant
When you are tired, your brain produces a chemical called adenosine. Adenosine binds to specialized receptors, which slows nerve cell activity and makes you sleepy. Caffeine has a chemical structure that is similar to adenosine and takes its place at the adenosine receptor site. Caffeine, however, works in a manner that is opposite to that of adenosine. It stimulates the activity of the nerve cells, so that instead of feeling sleepy, you are wide awake, energetic and alert.
References
- University of Maryland Medical Center; Caffeine in the Diet; May 2009
- Encyclopedia.com; Gale Encyclopedia of Mental Disorders: Caffeine Related Disorders; 2003
- MayoClinic.com; Nutrition and Healthy Eating: Caffeine Content for Coffee, Tea, Soda and More; October 2009
- John Hopkins Bayview Medical Center; Information About Caffeine Dependence; July 2003
- National Coffee Association: Coffee Science Source
