Nicotine

Summary: Cigarettes contain tobacco. Tobacco smoke contains: - tar – a sticky, black substance that builds up in the lungs and narrows the airways - nicotine – a drug (called a stimulant) that speeds up the nervous system, making the heart beat faster and narrowing blood vessels - carbon monoxide – a poisonous gas that stops the blood from carrying as much oxygen as it should. Tags: science student-book-7 biology Created: 2026-05-21 Last Updated: 2026-05-21

Nicotine

Cigarettes contain tobacco. Tobacco smoke contains: - tar – a sticky, black substance that builds up in the lungs and narrows the airways - nicotine – a drug (called a stimulant) that speeds up the nervous system, making the heart beat faster and narrowing blood vessels - carbon monoxide – a poisonous gas that stops the blood from carrying as much oxygen as it should.

Source

This concept is from the [Science Student Book 7](Science Student Book 7/Biology/Health and Lifestyle/3.6 Harmful substances.md), Biology section.