Almost everyone knows that smoking is harmful to health, most people who smoke are ever wanted to quit smoking, but only a few people will quit smoking successfully. The United States has had a statistics: 80% of smokers wanted to quit, but without the aid of nicotine replacement therapy, only 3 to 5% of people will quit smoking successfully. Why is quitting smoking so hard? In addition to psychological and social factors, mainly just about nicotine, because nicotine is a drug similar to what can be addictive.
When inside the human brain, there is an area called reward center, people engaged in some of the survival, reproduction essential activities, such as drinking, eating, mating, when the social reward center called dopamine is released material, people produce feelings of euphoria, which encourage people to continue to engage in these beneficial activities. However, smoking, drug abuse when, although these activities harmful than good, reward center will also be a large number of the release of dopamine reward. For example, when smoking, smoking the first bite, after a few seconds, the nicotine will arrive through the blood brain into the reward center, which stimulate the release of dopamine. This process is very fast, it is very addictive.
Contains a lot of nerve cells in the human brain, if you read the nerve cells under a microscope, you will find that they are very different from other cells in shape, it has a long projection. Nerve cells on contact with each other through these projections, to receive and transmit signals. Nerve cell projections contact each site, called synapses, if you look carefully, two nerve cell synapses are not linked together, leaving a gap in the middle. How the signal transmitted through the gap it? This time we need to use a class of chemical substances when the transmitter. One of the neuron receives nerve signals, at the end of its projections neurotransmitter release, neurotransmitter across the synaptic cleft, to the end of another nerve cell projections, there are many specific receptors on the cell membrane of these end neurotransmitter binding to these receptors, the signal will pass over.
A Neural first discovered neurotransmitter called acetylcholine, and it binds the receptor called acetylcholine receptors. Acetylcholine receptor is actually a made up of protein ion channel, the channel is normally closed. And after acetylcholine receptors, ion channel is opened, the extracellular sodium ions, potassium ions, calcium ions into the nerve cells, triggering a series of reactions. If the reward center, these subsequent reactions including the release of dopamine. Acetylcholine is then rapidly degraded, removed, ion channel receptors closed again, waiting for the next batch binding of acetylcholine.
Neurotransmitters and receptor binding, just like the keys and combination lock, is very specific. But nicotine like a forged key, can happen with a certain type of acetylcholine receptor (such receptors called nicotinic acetylcholine receptor), ion channels open, stimulate the release of dopamine. Furthermore, nicotine and acetylcholine receptor binding was also particularly tight, unlike acetylcholine as soon be removed, its half-life (cut in half the time) up to 2 hours. However, ion channels have been impossible to open, if the key has been inserted in the lock does not pull out, then the channel will be closing on their own. This process is called desensitization. Smokers continued smoking process, the body has been contains nicotine, the result is that most of the nicotinic acetylcholine receptors are occupied nicotine, and desensitization in the state, can not react to acetylcholine.
But the nerve signals had passed, ah, how to do it? Nerve cells have to produce more acetylcholine receptors, so that they can be combined with acetylcholine, nerve signals to ensure normal delivery. So the nerve cells of smokers, the number of acetylcholine receptors much more than the average person, occupied most of the nicotine does not work, the number of acetylcholine receptors can act only remaining and the average person almost. If smokers do not smoke for a long time, such as sleeping, or quit smoking, nicotine gradually removed the body, and those that had previously been occupied nicotine receptor empty out, can also be combined with acetylcholine. This time on the problem, much more than usual vacated receptors, related acetylcholine binding, transmission of nerve signals went wrong (the number of acetyl choline receptors more than capable of binding to the receptor number is controlled by a number), body appeared discomfort, there has been withdrawal reactions, especially smokers feel uncomfortable, as soon as one wants to suck, so the number of receptors in vivo empty back to normal. So once the smoking addiction, has not primarily to get a sense of pleasure, but in order to avoid uncomfortable.
Fortunately, this process can be reversed. If you insist on smoking, excess acetylcholine gradually removed by the experience, which is a lengthy process: six to 12 weeks after quitting, the body of nicotine was only completely cleaned, excess acetylcholine receptors was only cleaned by the number of body was restored to normal levels, no longer appear withdrawal reactions. So quit smoking when withdrawal reactions usually last for two months, we had this difficulty, considered quitting smoking. Most people do not have the willpower, we need the help of nicotine patches, nicotine gum and other nicotine replacement therapy, and gradually quit smoking.
(The answer from finishing Fang Sina blog)
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