Explain how smoking cigarettes increases the risk of cardiovascular disease.

Carbon monoxide in cigarette smoke binds to haemoglobin, forming carboxyhaemoglobin and reducing the amount of oxygen that can be carried by the blood. This means less oxygen is delivered to the heart muscle, creating a hypoxic environment.

Nicotine stimulates the sympathetic nervous system, causing an increase in heart rate and blood pressure. The higher blood pressure exerts additional mechanical stress on the arterial walls, damaging the endothelium.

Endothelial damage promotes the deposition of low‑density lipoprotein (LDL) cholesterol and other fatty substances in the arterial wall. Over time these form fatty deposits or plaques, a process known as atherosclerosis.

The plaques narrow the lumen of the arteries, restricting blood flow to the heart. They also create sites where blood clots can form, which can block the artery completely and lead to a heart attack.

Thus, smoking increases CVD risk by reducing oxygen delivery, raising blood pressure, damaging arteries, and promoting plaque formation and clotting.