The Anatomist - Bill Hayes [14]
She is answered by six shaking heads.
Dana points to two slim vessels emerging from the base of the aorta and snaking down the heart’s surface. These are the right and left coronary arteries. In what makes perfect sense now that it’s pointed out, the first destination for fresh, oxygen-rich blood is here. “Remember this phrase,” Dana tell us: “‘The heart feeds itself first.’”
Remember it? I’d like to contemplate it. But there is no time. Dana and the team are already focused on the right atrium. Through Amy’s doorway, they find the scar Dana had mentioned earlier, a thumbprint-sized indentation.
“In utero, this used to be a hole,” Dana says. During fetal life, blood passes not into the lungs but directly from the right to the left atrium through this shortcut. Though the baby is not breathing in a technical sense, it is getting plenty of oxygen, drawing it from the mother’s bloodstream through the placenta.
“But the shunt becomes obsolete at birth,” Dana continues, “when a newborn, gasping for air, uses its lungs for the first time.” This single act radically changes the pressure within the circulatory system, channeling blood into the lungs rather than away from them. No wonder a newborn howls. Within hours, the hole begins closing up, leaving behind this fossil of fetal life, the fossa ovalis. In some babies, Dana adds as we each take turns examining it, the shunt does not heal properly, leaving an actual hole in the heart, which has to be surgically repaired.
You cannot hold a human heart without questioning how it ever became known as the center of emotion or, as the grand sixteenth-century French surgeon Ambroise Paré once described it, “the chief mansion of the Soul, the organ of the vital faculty, the fountain of the vital spirits.” To me, the heart does not look or feel like anything but what it is, a tough, muscular pump. But wait, not so fast.
“Let me show you one last thing,” Dana says before moving on to the next group and the next body.
Massoud, Amy, and the rest of us crowd around her as she lifts up the cadaver’s heart and pulls the doorway into the right atrium as far back as it will go.
“Now, unfortunately, you can’t actually see it,” Dana says, “but, right inside here, where the superior vena cava enters the right atrium”—she points to a spot at the top of the fold—“right at that ridge is a little area where a cluster of cells is embedded. It’s called the sinoatrial node, or S-A node, but it’s known as the pacemaker.” She lets that sink in. “This is where your heart’s speed is set.”
While she explains how the S-A node works—electrical signals generated by these cells spread to other cells across the heart, causing it to contract, to beat—I find myself dazzled by this perfect meeting of anatomy and metaphor. In the human body, the node is positioned right under the sternum, dead center in the chest. So, in a sense, this truly is where feelings such as terror, love, and elation are first felt—where your heart starts to race, pound, flutter.
Looking up, I notice that Amy is doing exactly what I am doing: we both stand with a hand at the center of our chests, instinctively feeling the moment. Here, right here, is where wonder begins.
Three
“I HAVE TO SAY, KIDNEYS ARE ONE OF THE SADDEST-LOOKING creatures!” laments Dana during a lab presentation midway through the ten-week course. I have to agree. The sickly gray organ, which she had just removed from a demo cadaver’s lower back, looks pockmarked, blob-shaped not kidney-shaped, and, indeed, sad. Though larger, it reminds me of a testicle, or at least the testicles we had studied a couple of weeks earlier. Do I detect a family resemblance?
Indeed, in males the two are connected, not directly but venously, Dana goes on to explain. Bridging the twelve or so inches from the left testicle to the left kidney is the testicular vein, which feeds into the renal vein as blood returns to the heart. This particular anatomical arrangement occurs only on the left side.
“In fact