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First Half Marathon

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In the above photo, I am finishing my first half marathon. This was the Happy Girls Run in Spokane. The race was a good milestone as it has inspired me to continue to stay in good overall health during my undergraduate career. By staying in shape, I also am able to maintain good cardiovascular health. A central component of the cardiovascular system is the heart. The heart is one of the earliest differentiating and functioning organs embryonically. In human embryos, the heart will develop from the mesoderm and begin to beat in a little over three weeks.1 When the heart is fully formed, it will be about the size of a large fist. The heart serves as the circulatory pump for the entire body.2 Before understanding the physical theories behind the heart, it is useful to understand a little bit about the physiology of the heart. The heart is divided into four chambers: two atria on top and two ventricles on the bottom. The atrium and ventricles are separated by valves and the septum separates the right and left sides of the heart.3 Blood returns to the heart from the body through the veins, enters the right atrium and then flows to the …show more content…

The depolarization when discharging and then the repolarization in order to fire again is similar to a relaxation oscillator.5 This comparison of an SA node and a relaxation oscillator is useful in understanding how the heart is able to beat around 60-70 beats per minute. In the model of a relaxation oscillator there is a capacitor which is charged by a battery, however, the SA node is charged by the ion transport process of the membrane.5 The concentration gradient of ions is analogous to the charge within a capacitor and this is where the potential energy is stored. This potential energy is utilized when the SA node depolarizes or when the relaxation oscillator releases its

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