Explanation & Answer
Cigarette smoking is the leading cause of lung cancer, accounting for about 85% of lung
cancers. Risk for lung cancer increases with the duration, intensity and depth of smoke
Second-hand (passive) smoking also causes lung cancer, but is less strongly associated
compared to active smoking.
Cigarettes contain multiple carcinogens (more than 60) that have been shown to induce
cancers in laboratory settings.
Polycyclic aromatic hydrocarbons (PAH) such as benzo[α]pyrene produce
mutations in the p53 gene. G to T transversion within the p53 gene is a molecular
signature of lung tumours caused by tobacco mutagens.
N-nitroso compounds are a major group of chemicals found in tobacco smoke,
several of which are potent animal carcinogens.
Nicotine: causes addiction to cigarette smoking and is also a promoter for carcinogenesis.
Sympathetic/parasympathetic activation: nicotine binds to and activates
nicotinic cholinergic receptors, which are located on both sympathetic and
parasympathetic postganglionic neurons. The endogenous ligand for this receptor
is acetylcholine (ni...