Addictive substance in tobacco and the major factor responsible for continued and compulsive use of tobacco.

Pleasurable features are relief of anxiety and arousal.

Nicotine is the primary addictive compound in tobacco. 

Inhaling cigarette smoke delivers an arterial bolus of nicotine to the brain in 7 to 30 seconds at an  average of 1 mg of nicotine per cigarette, which activates the nicotinic receptors that mediate the release of dopamine in the reward pathways of the brain.

The rapid delivery of high concentration of nicotine make smoking the most addictive form of nicotine delivery.

Nicotine in meta-analyses of 41 clinical studies concluded that nicotine administration or smoking improves alerting and orienting attention and episodic and working memory and slightly improves fine motor performance.

Its quick absorption into the blood stimulates the adrenal cortex to release epinephrine, which then incites the CNS to cause an increased heart rate, respiratory rate, and blood pressure.

Nicotine binds to nicotinic acetylcholine receptors in the brain, releasing neurotransmitters such as dopamine whose rewarding effects become associated with specific circumstances or behaviors for the relief of  stress or negative emotions.

The repeated nicotine intake generates tolerance and physical dependence and produce withdrawal symptoms when nicotine blood levels fall.

Withdrawal symptoms include: cigarette craving, irritability, restlessness, difficulty concentrating, anxiety, and

Individuals who quit smoking frequently do not recognize these symptoms as withdrawal.

These behaviors, emotions, and situations become triggers to smoke.

Is carried by tar particles to the lung alveoli and then to the brain in approximately 10 seconds for each inhalation.

As addicting as heroin.

The addictive potential of tobacco depends on the speed of nicotine delivery to the brain and on the nicotine dose.

It is a gateway drug that lowers the threshold for addiction to other agents.

Signs of withdrawal are irritability, anger, frustration, depression, anxiety, difficulty in concentration, restlessness, weight gain, increased appetite, decreased heart rate and insomnia.

Increases the levels of dopamine, which controls pleasure and reward, just as in heroin and cocaine.

Chronic exposure may lead to addiction of nicotine, and acts as a gateway to possible addiction in general.

After inhalation of smoke the levels of the drug rises rapidly due to the large surface area in the lung circulation.

Blood enters the left side of the heart and rapidly reaches the brain.

Reaches the CNS circulation and interacts with specific CNS receptors required for the development of dependence.

Binds to and causes changes in nicotinic acetylcholine brain receptors.

Binds to the Alpha 4 beta 2 nicotinic cholinergic receptor, resulting in the release of dopamine and other neurotransmitters underlying reward processing in the brain.

Neuroadaption occurs with repeated nicotine exposure, resulting in tolerance and a withdrawal syndrome when a smoker tries to quit, and this includes irritability, cravings, nausea, and dizziness.

The main site of action is in the mesolimbic system of the brain.

The nicotine brain receptors are composed of 5 alpha and beta subunits with the highest concentrations the reward center of the brain, where stimulation of the receptors release dopamine.

Binding of nicotine to nicotinic cholinergic receptors in the brain.

Leads to neurotransmitter release, which makes smoking and smoking cues attractive and reinforcing.

Tolerance occurs with chronic smoking with proliferation of nicotinic receptors, and permits higher levels of self administration of nicotine.

When smoking decreases, a lack of binding to the nicotinic receptors results in withdrawal symptoms of craving, restlessness, negative moods and an intent to return smoking.

Increases cardiac output by increasing heart rate and myocardial contractility.

Increases arterial pressure and total body oxygen uptake above basal levels by 7%.

Approximately half of phenotypic variance in tobacco dependence is associated with genetics.

Increases myocardial oxygen consumption. And then to the brain.

Negative effects of withdrawal account for low success rate for smoking cessation.

No evidence exists that nicotine replacement therapy increases the risk of healing or cardiovascular complications.

It is an agonist of nicotinic acid acetylcholine receptors found throughout the nervous system and increase binding produces anti nociceptive effects.kl

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