July 26, 2010
The Effects of Caffeine on the Human Body
I. In a quote by Eddie Vedder, I read "Caffeine, the Gateway drug." Around 90 percent of Americans consume caffeine every single day in one form or another. Consuming as little as 100 mg of caffeine a day can lead a person to become "dependent" on caffeine, yet it is legal and unregulated in many jurisdictions. Making it the most popular drug by far. In this speech I am going to explain how caffeine affects the Human body. II. Caffeine is believed to work by blocking adenosine receptors in the brain and other organs. This reduces the ability of adenosine to bind to the receptors, which would slow down cellular activity. The stimulated nerve cells release the hormone epinephrine (adrenaline), which increases heart rate, blood pressure, and blood flow to muscles, decreases blood flow to the skin and organs, and causes the liver to release glucose. Caffeine also increases levels of the neurotransmitter dopamine. Caffeine is quickly and completely removed from the brain. Its effects are short-lived and it tends not to negatively affect concentration or higher brain functions. However, continued exposure to caffeine leads to developing a tolerance to it. Tolerance causes the body to become sensitized to to adenosine, so withdrawal causes blood pressure to drop, which can result in a headache and other symptoms. III. On a national level, Caffeine is the most widely used Psychoactive Substance
A. Psychoactive Drugs act on the central nervous system and alter the mood, cognition and perception of the user. Different psychoactive drugs produce different effects and are used for medicinal, social and ritual purposes. Psychoactive drugs are divided into four basic categories: depressants, stimulants, opiates and hallucinogens. Other popular Psychoactive Drugs include alcohol, antihistamines, barbiturates, the prescription drug Valium, nicotine, amphetamine, cocaine,...