Q.Which of the following substances in tobacco smoke damage the gas exchange system?

Tobacco use exposes the body to nicotine (addictive stimulant), tar (a mixture of carcinogens), and carbon monoxide, producing wide-ranging cardiovascular, respiratory, carcinogenic, and reproductive harm.

• Cardiovascular effects: Nicotine stimulates the adrenal medulla to release adrenaline and noradrenaline, raising heart rate and blood pressure; long-term use promotes atherosclerosis (fatty plaque build-up in arteries), increasing the risk of coronary heart disease, heart attacks, and stroke.
• Respiratory effects: Chronic irritation and damage to the airways and alveoli leads to chronic bronchitis and emphysema, collectively known as chronic obstructive pulmonary disease (COPD); tar deposits also directly damage lung tissue.
• Carcinogenic effects: Tar contains numerous carcinogenic compounds that are strongly linked to cancers of the oral cavity, throat, larynx, oesophagus, and lungs.
• Oxygen transport: Carbon monoxide in tobacco smoke binds haemoglobin more strongly than oxygen (forming carboxyhaemoglobin), reducing the oxygen-carrying capacity of the blood and causing tissue hypoxia. …