Nicotine constricts or narrows your blood vessels, limiting the quantity of blood that gets to your organs. Constant constriction causes blood vessels to stiffen and become less elastic over time. Blood artery constriction reduces the quantity of oxygen and nutrients delivered to your cells. This may help explain why smokers have more heart attacks, strokes, and other cardiovascular diseases than non-smokers. Smoking also slows the movement of your blood as it flows through your arteries. The amount of time it takes for blood to travel from your heart to your lungs is called the "heart rate". The faster your heart beats, the more often its valves open, allowing blood to enter into it; this is what gives rise to the expression "a beat per minute". When your heart beats too slowly, it has time to fill with blood and then contract again before it has to release its pressure on the blood it has pumped up into the pulmonary system. This is called "bradycardia" and it can be a sign of serious heart disease. By slowing down the movement of blood in your arteries, smoking can also affect how well your heart muscles function. If you're not getting enough oxygenated blood to your heart, it will work harder to pump itself out to the rest of your body. This is called "coronary arteriosclerosis" and it can lead to heart failure if it's not treated quickly.