Effects of smoking on blood Mr. Smart has tried to stop smoking, but has not been successful. He wants to know why it matters and the effects of tobacco on his heart and blood vessels. Let’s explain: There are many chemicals in cigarettes and cigarette smoke that can damage your heart and blood vessels. Two chemicals, nicotine and carbon monoxide, interfere with your cardiovascular system’s ability to function properly. Exposure to nicotine and carbon monoxide change your heart and blood vessels in ways that increase your risk of heart and cardiovascular disease. Nicotine causes your blood vessels to constrict or narrow, which limits the amount of blood that flows to your organs. Over time, the constant constriction results in blood vessels that are stiff and less elastic. Constricted blood vessels decrease the amount of oxygen and nutrients your cells receive. To meet the need for more oxygen, your heart rate may increase. Carbon monoxide binds hemoglobin, the molecule i