How does nicotine reach the brain after cigarette smoke is inhaled?

When cigarette smoke is inhaled, nicotine is absorbed rapidly through the lungs. It diffuses into the bloodstream as efficiently as inhaled oxygen and is then carried directly to the brain.1

This process is remarkably fast, with nicotine reaching the brain in less than 10 seconds. Once it arrives, nicotine binds to nicotinic acetylcholine receptors on the surface of neurons. This binding acts like a key in a lock, triggering the neurons to transmit nerve impulses and stimulating the release of various neurotransmitters, such as dopamine, norepinephrine, and serotonin. The release of dopamine within the brain's reward pathways is particularly significant, as it reinforces the behavior and contributes to the highly addictive nature of tobacco use.1234