This is about the heart. Break it down to a purely physical description, and describe it as “a hollow muscular organ that pumps blood through the circulatory system by rhythmic contraction and dilation.” This is a start. There is significantly more to a heart. More physical detail helps. In humans there are 4 chambers, two atria, and two ventricles. A normal sized heart is comparable to a human fist and weighs about 10.5 ounces.
The average human heart rate is 60-80 beats per minute(bpm).
To understand the significance of the human heart rate let’s compare them with animal heart rates. A hibernating groundhog rate is 5 bpm. The Blue Whale 8-10 bpm. Horses have a bpm of 28-40. A mouse has a bpm of 450-750.
Invertebrate hearts are very different physically from humans. Insects are known to have an open circulatory system. Their internal organs “float” in blood. Insect blood is called “hemolymph.” Insects hearts are found in their abdomens. Usually there is a tube at the top of the insect’s back which has holes to take in the “hemolymph” and pump it towards the head.
Large insects like the bumble bee use the muscles of their wings to increase heart rate and blood flow and warm their bodies on cold mornings. This makes bumble bees important pollinators. They begin pollinating earlier in the day and continue longer as evening temperatures ground other pollinators. We do not know the heart rate of insects. Yet a honey bee flies at a rate of 15 mph and will travel up to 3 miles to collect plant nectar. Its heart rate must be elevated after such exertion.
What causes human hearts to beat rhythmically, steadily night and day for an average of 79 years? Do you ever need to tell your heart to beat? Medical science identifies the sinoatrial node as the “heart’s natural pacemaker.” This tiny cluster of specialized heart cells send electrical impulses which produce a heart-beat. It works for a lifetime.
Now the question behind what causes the heart to beat. What causes the sinoatrial node to send electrical impulses?
Have you ever taken your pulse, or placed your hand over your heart and felt your pulse? Yes, diet, stress and exercise impact heart health. But our hearts function a lifetime, and we have little to do with it. It’s really a miracle. My favorite shepherd who also was a king, David said of God, “Your eyes saw my unformed body. All the days ordained for me were written in your book before one of them came to be.” (Psalm 139:16) God knows your heart. He made your heart and knew how many times it would beat-before you were born. That’s how powerful, how wonderful God is.
There is great comfort in this. Your heart beats free at no charge for you-all of life. God does that for you. God directs the sinoatrial node to function.
This is also about the heart that lives beyond death, your soul. He knows the number of your days. He knows the sin in your heart for each of those days. He did something for us about that. He sent His Son Jesus to clean our soul-heart, the eternal heart, from sin which separates us from God.
Consider the words of the shepherd/king once more, “From his dwelling place he watches all who live on earth— he who forms the hearts of all, who considers everything they do.” (Psalm 33:14-16) God is in the heart business, yours and mine. He’s the ultimate expert in hearts.