Smoking raises your blood pressure and puts stress on your heart. Over time, stress on the heart can weaken it, making it less able to pump blood to other parts of your body. Carbon monoxide from inhaled cigarette smoke also contributes to a lack of oxygen, making the heart work even harder. This increases the risk of heart disease, including heart attacks.
Smoking makes your blood thick and sticky. The stickier the blood, the harder your heart must work to move it around your body. Sticky blood is also more likely to form blood clots that block blood flow to your heart, brain, and legs. Over time, thick, sticky blood damages the delicate lining of your blood vessels. This damage can increase your risk for a heart attack or stroke.
Smoking increases the amount of cholesterol and unhealthy fats circulating in the bloods, leading to unhealthy fatty deposits. Over time, cholesterol, fats, and other debris build up on the walls of your arteries. This buildup narrows the arteries and blocks normal blood flow to the heart, brain, and legs. Blocked blood flow to the heart or brain can cause a heart attack or stroke. Blockage in the blood vessels of your legs could result in the amputation of your toes or feet.