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Human Circulatory System Essay

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It does not matter what animal, seastar or human, every single animal has a circulatory system. When one visualizes a circulatory system, he or she imagines a beating heart with blood vessels spreading across the body. Definition of circulatory system according to a scientific source: “The system in the body by which blood and lymph are circulated.” - Boundless Textbook. In other words, a heart is not required to be a part of the circulatory system. The human circulatory system has a more complex physiology and anatomy compared to echinoderms.

Humans have a system that circulates through the body through millions of blood vessels, delivering oxygen to cells that require the substance. The system is consisted of a heart, lungs, different
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As the blood flows into the capillaries from the aorta, the oxygen rich blood coming from the heart gives away it’s nutrients, turning into oxygen poor blood as they flow back to the heart, eventually picking up nutrients in the lung capillaries again. Instead of going through the aorta, now they go through the superior (top) or inferior (bottom) vena cava, which like the aorta is very thick, however carries oxygen poor blood instead. When the blood arrives back to replenish their cells, that’s the equivalent of a literal lap around the circulatory system.

The circulatory system consists of many different components and structures for specific functions. For example controlling the blood flow to go one direction, for one blood vessel to hold more blood than another, and even a system that decides when the heart beats. As the circulatory system was studied and observed, questions were raised of how the blood flow goes only one way. In the heart and between each chamber, there are four valves that control the amount of blood flow in the heart. As the oxygen poor blood flows into the right atrium through the respective vena cava’s, it is stopped until the heart contracts and the tricuspid valve opens, letting the blood flow into
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