When it comes to a properly functioning heart, calcium plays an essential role. As with any nutrient, calcium has many different functions inside of the body. While most think of calcium only to help build bones, the role of calcium far outreaches bone growth alone. Without calcium, your heart would not be able to beat or contract properly.
Electrical Conductivity
The heart begins to beat through a spontaneous excitation of specialized cardiac cells. A beat begins as a group of cells called the sinoatrial node, or SA node, depolarize. Depolarization results in a contraction that prompts the atrioventricular node, or AV node, and ventricles of the heart to contract in rhythm.
Calcium and the Heart Beat
The SA node, also known as the heart's pacemaker, has the ability to spontaneously depolarize and contract when positive ions, which normally reside outside of the cell, rush in. The resting state of your cardiac cells is negative 60 mV, as depolarization occurs the cells increase up to zero mV. Positive sodium ions begin to slowly seep into the SA node cells, which opens the gates for positive calcium ions to rush in. Without these calcium ions moving into the SA node cells,a heart beat could not be started.
Significance
Calcium helps the beginning of a heart beat but it is also a mediator in prompting the other cardiac cells to beat. Once the SA node depolarizes, slow calcium channels open to the other cardiac cells. It is calcium's job to enter these cardiac cells and bind to the muscle fibers to trigger a contraction. Calcium is stored inside of cardiac cells, much like skeletal muscle cells, in preparation for contraction.
Hypercalcemia and Hypocalcemia
Hypercalcemia is caused by an excess of calcium. Too much calcium can be hard on the heart and cause a decrease on the heart rate. Hypocalcemia occurs when there is too little calcium in your body and results in a rapid increase in heart rate. These two disorders affect the heart rate by influencing the contraction strength of the heart beat. Luckily, even with a moderately healthy diet, calcium imbalances are rare.
Recommended Intake
Your doctor can tell you for sure if you are at risk for developing calcium in your arteries. However, you might want to consider getting checked if you have two or more risk factors. Risk factors include diabetes, high blood pressure, high cholesterol, smoking, inactivity, unhealthy body weight or a family history of heart disease.
References
- "Anatomy and Physiology"; Kenneth S. Saladin; 2004
- "Exercise Testing and Prescription"; David C. Nieman; 2007
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