What is Nicotine?

Nicotine (C10H14N2) is a naturally occurring alkaloid. An alkaloid is an organic compound made out of carbon, hydrogen, nitrogen and sometimes oxygen. These chemicals have potent effects on the human body. For example, many people regularly enjoy the stimulating effects of another alkaloid, caffeine, as they drink a cup or two of coffee in the morning.

Nicotine normally makes up about 5 percent of a tobacco plant, by weight. Cigarettes contain 8 to 20 milligrams (mg) of nicotine (depending on the brand), but only approximately 1 mg is actually absorbed by your body when you smoke a cigarette. This is why it is important to pay attention to the concentration of nicotine in your E-juice or cartomizer.

Nicotine moves right into the small blood vessels that line the tissues of the airways. From there, nicotine travels through your bloodstream to the brain, and then is delivered to the rest of your body.­

 Although nicotine takes a lot of different actions throughout your body, what it does in the brain is responsible for both the good feelings you get from smoking, as well as the irritability you feel if you try to quit . Within 10 to 15 seconds of inhaling, most smokers are experiencing nicotine's effects. Nicotine doesn't stick around your body for too long. It has a half-life of about 60 minutes, meaning that six hours after a cigarette, only about 0.031 mg of the 1 mg of nicotine you inhaled remains in your body. That's why people light up so often, to keep their "nicotine level" up!

Nicotine changes how your brain  functions. The  results are somewhat of a paradox: Nicotine can both stimulate and relax a smoker, depending on how much nicotine is consumed. This effect is not uncommon. Although the actions of nicotine and caffeine in the body are quite different, you also see dose-dependent effects. This is true of alcohol as well. When you have your first drink, it may loosen your inhibitions and lower your defense mechanisms, and you're having fun! After several drinks, well, that's why there are DUI limits.

Nicotine initially causes a rapid release of adrenaline, the "fight-or-flight" hormone. The "fight or flight" hormone was very useful to cavemen, early settlers and hunters. It kept them safe in a fear laden world. They had to act fast, fight or flight! That rush of adrenaline helped them think or move quickly by:

• Increasing the heart rate
• Raising blood pressure
• Rapid, shallow breathing

Adrenaline also tells your body to dump some of its available glucose into your blood for rapid energy. Nicotine itself may also block the release of another hormone called insulin. Insulin tells your cells to take up excess glucose from your blood. Having more sugar than usual in the blood provides more fuel. Some people think that nicotine also curbs their appetite so that they eat less. This hyperglycemia could be one explanation why: Their bodies and brain may see the excess sugar and down-regulate the hormones and other signals that are perceived as hunger.

Nicotine also helps the brain release and use certain neurotransmitters like; Dopamine. which is responsible for feelings of well-being, Glutamate, which is associated with learning and memory, and Endorphins, which are related to mental sharpness and pain control. Many athletes push that extra mile seeking that "rush" of Endorphins. As well as Serotonin and Norepinepherine. These effects make nicotine very habit forming if not addictive. 

The hazards of ingesting nicotine by smoking come from the combustion of the tobacco leaves.  Much like inhaling a campfire or smoke from a house fire or anything else on fire.  The tars are produced from combustion.

Resources: http://science.howstuffworks.com/nicotine.htm ,http://en.wikipedia.org/wiki/Nicotine