Nicotine is… unique again. It enters through your lungs as tar (oh joy! Cancer!), but via this method, it enters the brain in 7 seconds, which is twice as fast as IV, which also explains why nobody really shoots up tobacco.
It’s broken down by CYP2A6, another cytochrome common in the liver, to cotinine. It is excreted 90% in urine and 10% in breath. Ew.
It increases calmness and relaxation in regular smokers who have gone a period of time without smoking (i.e. first smoke of the day, or smoke during lunch break), but in new smokers it’s more likely to cause tension or arousal, lightheadedness, dizziness, nausea.
It has positive motor functioning and cognitive accuracy affects, as well as reduced response latency which… is not what you think of when you think of someone smoking, but I guess it explains the jitters.
What’s actually happening in your brain? Acetylcholine. The neurotransmitter acetylcholine, which is excitatory, binds to nicotinic receptors (nAChRs) in the cortex, limbic system, and base of the brain (so… everywhereish?)
There is also, surprise, a dopamine aspect as it increases dopaminergic firing AS WELL AS presents dopaminergic breakdown via the enzyme MAO.
FINALLY, Norepinephrine and epinephrine, responsible for sympathetic nervous system activation, increase firing.
So tada! Tobacco. Don’t do it, kids. It’s addicting, it sucks, and the cost is worse than the reward is good. The end.