Does Calcium Maintain The Heartbeat?

Though calcium is most well-known for its involvement with the health of your bones, it is also essential for your heart. Calcium is a mineral, a positively charged ion that is responsible for the initiation and transmission of your heartbeat. This complex process is finely tuned to keep your heart beating on time and in rhythm.

How the Heart Beats

The heart muscle cells are the only cells that spontaneously contract themselves. This occurs through a rush of ions in and out of the cell that causes a depolarization and subsequent contraction. A normal heart beats between 70 and 80 beats per minute, each time delivering much needed blood to the cells that need it.

SA Node

The SA node is a specialized group of cells that initiate your heart beat. The SA node cells rest at a negative 60 mV -- this is known as their resting membrane potential. Slowly, the positive ion sodium seeps into the cell until it reaches negative 40 mV, at which time the fast calcium channels open, allowing for a rush of the positively charged ion of calcium into the cells and bringing them to a neutral zero mV -- initiating a contraction.

Myocardial Contractions and Calcium

The SA node begins the contraction, but all of the rest of the myocardial cells must also contract for your heart to beat. This begins also with sodium slowly entering the cells, which triggers a positive feedback cycle and leads to the release of calcium into the cell from the extracellular fluid. As calcium enters, it binds to the calcium channels inside the cell, triggering the cell to release its stored calcium ions. All of this leads to the cardiac cell's ability to produce a rhythmic contraction, which allows the heart to pump blood.

Calcium Recommendations

Your heart's need for calcium is finely tuned. Getting too much calcium can lead to hypercalcemia, a condition marked by an irregular heart beat. Adult men should take in 1,000 mg of calcium daily. Women also need 1,000 mg per day until they reach 55, when the recommendation increases to 1,200 mg per day. Calcium is found in many foods, including dairy, vegetables, soy, nuts and beans.