Nervous System
It is no secret that smokers are addicted to cigarettes, making it hard for them to quit. This happens because activities in the nervous system and receptors in the brain can cause addiction. The person becomes more tolerant of nicotine, but it is the brain that develops certain levels at which nicotine is needed, so the brain can receive the pleasure it now desires from each cigarette, according to research published in the Archives of Environmental Health. This level increases as more nicotine is introduced, so it becomes more difficult to satisfy the brain, making addiction stronger. This process is responsible for the withdrawal symptoms smokers experience when they try to quit. After nicotine is inhaled and enters the bloodstream, it reaches the brain receptors that release dopamine. Dopamine is believed to cause the pleasurable and positive feelings a smoker experiences. With more cigarettes, the smoker becomes hooked.
"Feel Good" Chemicals
Changes in smokers' brains have been found on brain scans that shows so-called "feel good" chemicals, called endogenous opioids, being released. These chemicals become active in the brain after smoking. Endogenous opioids heighten positive emotions and prevent painful sensations, similar to the effects stimulated by heroin and morphine, according to scientists at the University of Michigan. Following the smoking of a cigarette the opioid flow increased by 20 to 30 percent in regions of the brain that help control emotions and craving. Changes in the flow seen on the brain scan correlated with how the smokers said they felt before and after smoking, according to the researchers. The subjects rated their feelings while smoking cigarettes with almost no nicotine and regular cigarettes. The regular cigarettes made them feel more relaxed and less alert, matching the changes in the brain scans.
Brain Damage
It's not just addiction smokers have to worry about. Now there is evidence that smoking can cause brain damage. A compound in tobacco causes white blood cells in the central nervous system to damage healthy cells, say researchers at the Indian National Brain Research Center. The compound, called NNK, is a chemical substance that becomes carcinogenic when changed through metabolic processes in the body. It can harm the nerve cells and cause severe neurological damage, according to the study published in the July 2009 issue of the Journal of Neurochemistry. The study was done on lab mice and shows that NNK causes the brain's immune cells, which usually attack damaged or unhealthy cells, to attack healthy cells.
