By Sara Thompson
Special to the Enterprise
Hearts denote love and affection, especially around Valentine’s Day. The central location of the heart in our bodies is what was thought to be the center of our emotions and what makes us "human". The classic phrase of having one's heart "skip a beat" when looking at a loved one could have been caused by either butterflies in the stomach, or a rush of adrenaline increasing the heart's rate. The symbolism of the heart has been around for centuries, but the physical mechanism of how the heart works and keeps us alive is very fascinating.
Our heart, like all mammals, has four chambers in it. Two atria, the left and the right, and two ventricles, also left and right. Both left and right atriums receive blood from other places in the body, and both ventricles push it back out. The heart is contained and protected by a small sac called the pericardium. Connective tissues connect to the pericardium instead of directly on the heart to keep it in place. Throughout the body are arteries that carry blood away from the heart, and veins that carry it back.
Blood coming back to the heart from the body first enters the right atrium. This chamber fills from two large veins, one from the upper body and the other from the lower respectively. This blood does not have oxygen and is carrying carbon dioxide generated from the body. The collected blood then enters the right ventricle from a valve separating the two. The deoxygenated blood is then pushed through another valve and sent to the lungs via the large pulmonary arteries. In the lungs, the blood deposits the collected carbon dioxide and absorbs oxygen. Then the newly oxygenated blood enters the left atrium and flows down into the left ventricle from another valve. From here the heart pumps the oxygen-rich blood through the aorta and to the rest of the body to start the process over again.
The valves within the heart keep the blood flowing one-way, and the chambers are separated by walls and connective tissues. The chambers and walls prevent the blood from mixing so only oxygenated blood is being transported to the body, and deoxygenated blood is returning to the proper location to receive oxygen from the lungs. A heartbeat consists of two parts, one being the flexing of the atria pushing blood to the ventricles, and the other being the flexing of the ventricles to push blood out of the heart, either to the lungs or the body. Each chamber fills when that part of the heart is relaxed and is moved by the flexing.
For an organ that is about the same size as your fist does quite a lot to keep us healthy and alive. The human heart is very intricate and requires precise timing for everything to work properly.
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