Heart Throb



The heart is divided into four chambers. The upper two are called the left and right atria. The bottom two are the left and right ventricles. In the normal heart blood is pushed (pumped) from the atria into each respective ventricle. The ventricles then contract to eject blood into the circulation.

The heart muscle itself is unique of all the muscles in the human body. Only in the heart can cells initiate their own electrical discharge. It’s a process called ‘automaticity.’ As the electrically charged ions (potassium, sodium, chloride, and calcium) move into and out of each cell, they initiate an electrical impulse.

Unless those electrical discharges could be better utilized, nothing more than a ‘twitching’ would occur in the tissue around each cell.

Life, however, could not exist if nothing but a ‘twitching’ occurred in the heart. What the body needs is a coordinated ‘contraction’ of an entire set of cardiac muscle to pump blood from the heart into the body’s circulation. Random and chaotic twitching would simply slosh the blood around in the chambers.

So, what do we find in the heart that permits us to live? A group of cardiac cells have been bunched together in the upper right side of the right atria. Physiologists call it the Sino-Atrial (SA) Node. It’s also called the heart’s ‘pacemaker.’

The SA node initiates a coordinated electrical impulse – 60 to 100 times each minute. The impulse spreads through both atria, producing a coordinated pumping action that sends blood into both ventricles.

The electrical impulse from the SA node then travels to another group of cells at the junction of the atria and the ventricles, called (appropriately) the Atrio-Ventricular (AV) node.

This node holds onto the SA impulse for a fraction of a second to ensure all the blood being pushed into the ventricles has time to get there. Then it sends the impulse along to the next set of specialized cells in the ventricular walls. Those cells make up the Purkinje Fibers.

When the Purkinje Fibers cause the coordinated contraction of the left and right side of the heart, blood is expelled from the heart and into the body circulation.

Either it is yet another extraordinary piece of accidental evolutionary luck that those nodes all appeared at the right places at the right times for life to exist . . .

Or the Creator planned it that way.


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