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The Love Muscle: The Cardiovascular System

Yes, it's now February. Hearts are everywhere we look. It's that time... to celebrate love with Valentine's Day. So we thought it rather fitting that we take a closer look at the hearts that really matter- the ones that keep us going every single moment of every day. Our cardiovascular system is made up of multiple components that are all constantly working together as a single, seamless unit to nourish, cleanse, and restore the body. It is both one of the most vital body systems, as well as one of the most vulnerable and abused. This is why 1 in 4 deaths in America each year are related to cardiovascular disease. Perhaps a better appreciation and understanding of this amazing machine can help us protect our hearts and keep them healthy and strong for many years to come.

Our hearts do incredible things. They pump over 2,000 gallons of blood through our vast circuitry of blood vessels every day. Just the energy that the heart uses each day could power a truck for 20 miles. It's incredible! Yet it seems that our hearts are so underrated. We often prefer to think of the romantic symbolism and emotional idea of the heart rather than the intricate and powerful system it is. So often we only notice it when it skips, races, or does something that scares us. Why is it that we take it for granted? It pumps our very life force through our veins and keeps us going. It will beat roughly 2.5 billion times in the course of your existence, giving you steady, persistent LIFE.

So what are the mechanics behind this incredible system? Let's break down the electrical conduction system of the heart.

It all starts with a spark- well, not technically. But it does begin with specialized cells

which produce the electricity which powers the heart. These cells are often referred to as the heart's "pacemaker" and make up the sinoatrial (SA) node (also known as the sinus node). They are able to quickly reverse their electrical charge to create a heartbeat. When the heart is relaxed the inside of each cell has a negative electrical charge, while outside the cells the environment is positive. Some of the cells' negative atoms are allowed through the cell membrane, and this depolarization creates the electricity of the heart. Once a cell depolarizes, it sparks a chain reaction and electricity flows from cell to cell. When cells return to normal it's called repolarization, and the heart muscle relaxes once again. This amazing process is repeated with every heartbeat. In this way, our heart rhythm is created. After these electrical impulses are created by the SA node, the atrioventricular (AV) node takes over. This is a tiny bundle of special cells which is located near the center of the heart near both the atria and ventricles. It is responsible for relaying the electrical impulses that the sinus node creates between the atria and ventricles, making your heartbeat steady and consistent. The AV node delays the electrical impulses by .09 seconds to ensure that the atria have emptied their blood into the ventricles before the ventricles contract. This is vital to normal, healthy function and rhythm of the heart. The Bundle of His is yet another group of special cells directly carrying the electrical impulse from the AV node to the Purkinje fibers. The Bundle of His transmits the impulses via the left and right bundle branches, through the Purkinje fibers, and to the corresponding (left or right) ventricle, forcing it to contract and pump blood out of the heart. These parts all work together to create each heartbeat- typically 60-70 per minute. How amazing is that?!

So now that we know how the heart beats, let's look at how our blood flows through the heart and body.

Unoxygenated blood from the body flows into the heart through the vena cava and into the right atrium. From there, it gets pumped into the right ventricle and then into the lungs via the pulmonary artery. The lungs oxygenate the blood and help clean the blood by filtering out and releasing gasses such as carbon dioxide. From there the now oxygen-rich blood flows back into the heart's left atrium through the pulmonary veins and then into the left ventricle. After cycling through the heart and lungs, the oxygenated blood is ready to make its circuit throughout the body's 60,000 miles of blood vessels!

The blood is the life force of the whole body. It carries nutrients, hormones, electrolytes, steroids and oxygen to every tissue in the body. It also works with the lymphatic system to remove wastes from the body. It keeps the body alkaline and regulates body temperature. All of these vital functions are completed via the circulatory system.

Blood in itself is considered by some to be a living tissue. It is made up of formed elements (red blood cells, white blood cells, and platelets) and plasma. Your plasma is over 90% water. The rest is comprised of various nutrients, protiens, ions, gasses, and metabolic by-products. The formed elements, or blood cells are erythrocytes and leukocytes.

Erythrocytes are red blood cells. They contain hemoglobin, comprised of an iron atom (heme), which binds to an oxygen atom (and gives the blood its red coloration) and globin (a protein which binds to carbon dioxide). These cells transport oxygen and carbon dioxide. Since carbon dioxide lowers the body's pH, an enzyme in red blood cells called carbonic anhydrase changes carbon dioxide into hydrogen and bicarbonate ions. The lungs convert the hydrogen and bicarbonate ions back into carbon dioxide, which can then be safely exhaled through the breath. In this way, the blood acts to stabilize pH in the body, keeping tissues safe from acidosis.

Leukocytes are your white blood cells and are broken down into various subcategories based on their functions. All white blood cells are immune cells, and help your body fight off and neutralize foreign materials whether it be bacteria, viruses, or an object such as a splinter.

How lucky are we that we have such an amazing system working around the clock to ensure that we continue enjoying this beautiful life? We get to experience it all in this existence- joy, fear, excitement, adventure, stress, and most importantly LOVE. And behind it all, our heart will be there measuring out each pump, beating faster when we are afraid or stressed. Our blood, veins, and arteries will be there carrying those hormones and endorphins which allow us to feel all of those emotions. Our heart drives our passions, our fire for life because it keeps us going onward. In essence, the heart is love.

From our heart to yours-

Happy Valentine's Day!

For some very interesting videos about the heart, check these out! They depict the helical heart- the shape and design of our heart, which is a continuous band of muscle winding around itself in a vortex until it forms each chamber. It truly shows the intricacy and miraculous nature of the human heart.

(***TRIGGER WARNING*** Please note that these videos show real, dissected heart tissue.)

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