Explain how chemicals present in cigarette smoke are able to enter the body and reach the brain

When you smoke a cigarette, the components; e.g. nicotine and carbon monoxide enter the lungs and are absorbed into the bloodstream. They are carried by the Red Blood Cells to the blood-brain barrier, here, nicotine binds to nicotinic acetylcholine receptors (nAChRs), resulting to a cascade that results to release of dopamine (good-feeling neurotransmitter).

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

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