With our 19 year old being a huge European football fan, and my husband being a former middle school soccer coach, you can understand why we have been glued to the television watching the 2010 FIFA World Cup from South Africa. The fast pace, almost goals, fouls, true goals, shoot outs, and much discussed Vuvuzela and its sound…it’s all rather adrenaline pumping for the players, let alone the audience!
Over these past two weeks, as I watched, listened and took notes on Marian Diamond’s two cardiology lectures, it was impossible not to think about the players’ hearts and the hearts of their respective country folk cheering them on.
A human heart is fairly small, about the size of a fist. Make a fist and take a good look at it. Imagine a hollow muscle that size located inside the upper left side of your chest, about 5 inches long and 3 inches wide and weighing less than a pound, nestled on a angle, with the flatter end facing your right shoulder and the more distant point facing your left hip. According to my Human Anatomy & Physiology text, a sure fire way to feel your heart beating is to “press your fingers between the fifth and sixth ribs just below the left nipple.”
Another way to picture your heart’s location is to envision it settled in the mediastinum, the area between your two lungs. It is accompanied in the mediastinum by the trachea, bronchi, esophagus (coming from behind), thoracic duct (which carries lymph), phrenic and cardiac nerves, and lymph nodes.
Our heart functions as a highly efficient pump, sending blood out into three different circulatory routes.
- Pulmonary circulation sends deoxygenated blood coursing from our heart to our lungs, where it picks up oxygen and then returns to our heart.
- Systemic circulation sends the oxygenated blood throughout our body. This blood has a number of functions, most of which involve transportation of necessary nutrients, gases, and wastes.
- Coronary circulation provides nourishment for the heart proper.
Just think how strong the walls of the heart have to be in order to keep those soccer players running for 90+ minutes with their furiously alternating bursts of speed! The superior vena cava (above the diaphragm), inferior vena cava (below the diaphragm) and coronary sinus return deoxygenated blood to the heart. The blood then takes a path through the right atrium, tricuspid valve, right ventricle, pulmonary trunk, semilunar valves, and right and left pulmonary arteries to arrive in the lungs where it picks up oxygen. The newly oxygenated blood then returns to the heart, passing through four pulmonary veins, the left atrium, bicuspid valve, left ventricle, ascending aorta and the semilunar valves as it then finds its way back to the rest of the body, before repeating the entire sequence.
Heart valves prevent blood from flowing backwards, and the heart’s own internal pacemaker, also called the sinoatrial node, initiates the signal that keeps our heart beating. Purkinje fibers then carry that impulse to the ventricular walls, causing the walls to expand and relax (diastole) and then contract (systole) to move the blood along.
Peter Gabriel’s heart may be going boom boom boom in Solsbury Hill, but for the rest of us our hearts are generally going lub dup at 72 beats per minute. Not so for those FIFA soccer players; their hearts are easily beating at least 150 beats per minute! Once again, think about how strong and persistent our cardiac muscle is!
@brainbits: Our fist sized heart (valves & chambers) controls pulmonary circulation (heart–lungs–heart) & systemic circulation (heart–body–heart)
@brainbits: Our mediastinum (area b/the 2 lungs) contains our heart, vessels, trachea, bronchi, esophagus, thoracic duct, nerves & lymph nodes
@brainbits: Rhythmic “lub dub” of your heart=AV valves (lub) & semilunar valves (dup) closing. AV valves are larger so lub is stronger & longer.
@brainbits: “…enjoy the fun of solving puzzles w/your knowledge b/c then you feel good about it. Then we know you understand it.” M. Diamond
@brainbits: “Have you ever SEEN your heart in a sonogram? …That’s really exciting! You just lie there and watch it pump. Very clear.” M. Diamond
@brainbits: Not quite 1/3 thru M. Diamond Human Anatomy lecs & am embedded in odyssey of discovery. Want to visit a lab & see anatomy “up close”!