Your heart beats about 100,000 times a day, and every beat is a symphony. Each is a perfectly timed, carefully synchronized flow of electric current over a precise pathway on the heart's surface. This rhythmic flux literally wrings the blood out of the heart and pushes it through the 60,000 miles of arteries, capillaries, and veins that comprise your circulatory system. Arteries carry oxygen-rich blood away from the heart to the capillaries, where nutrients and oxygen flow out into the tissues. Veins collect the de-oxygenated blood from the capillaries and carry it back to the heart and lungs for replenishment.

Heart muscle cells are unique in the body. They pulsate without any external stimuli: a heart removed from a human body will continue to beat for hours. For every beat, your heart generates an electrical impulse that travels through the heart and causes each part of it to contract and relax in sequence.

The rate at which your heart beats is modulated by your autonomic nervous system, which controls functions in your body not under your conscious control. Baroreceptors, pressure-sensitive nerve endings found in the aortic arch, carotid arteries, walls of the auricles of the heart, and vena cava, are sensitive to changes in blood pressure. If your pressure is too low or too high, the baroreceptors send messages to your brain. It in turn sends signals to your heart to speed up or slow down, and to your blood vessels to constrict or dilate, as necessary, in order to increase or decrease blood pressure.

More on this topic

What are Arrhythmias? (VIDEO)
What Makes Your Heart Beat?
Blood's Pathway
The Electric Heart
Symptoms of Arrhythmia
Heart Disease & Arrhythmia
Risk Factors
Testing & Diagnosis
Resetting the Heart's Rhythm
A Heart Healthy Lifestyle

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