The Heart and Circulation of Blood

In this research paper, I will be analyzing the process of blood circulation within the human body. I will be focusing on the pulmonary circuit and the systemic circuit, as well as the relationship with the hepatic portal system. The combination of these systems allows the body to function properly and maintain unconscious homeostasis. I will also be talking about the effects that fitness and diet have on these processes. The pulmonary circuit passes already-used, deoxygenated and carbon dioxide-rich blood from the heart to the lungs in order for that the blood to become oxygenized.

Once oxygenized, the blood is distributed throughout the body via the systemic circuit, being transported in arteries. With the oxygen of the blood having been diffused into tissue cells, the blood that has gone through the digestive tract enters into the hepatic portal system, while blood that has not gone through the digestive tract is transported directly back to the heart.

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The blood that has done down the digestive tract is brought by the hepatic portal vein to the liver, to be filtered and cleaned before going back to the heart.

For the blood to get back to the heart, the liver empties the clean blood into the hepatic vein, leading to the inferior vena cava, which pumps blood into the heart’s right atrium. The cycle then begins again, as the blood in the right atrium makes its way into the pulmonary circuit again. I will talk about these three processes in my paper. The pulmonary circuit is where the blood becomes revitalized and useful again.

Deoxygenated blood, blood whose strength has already been used in the body, travels from the right atrium to the right ventricle through the one-way tricuspid valve.

The blood is then pumped into the pulmonary artery. The pulmonary artery is unique, as it is the only artery that carries deoxygenated blood, whereas it would usually be carried by veins. The blood is then taken into the lungs in order to reach the alveoli, where the blood is enriched, and the exchange of carbon dioxide and oxygen in the blood take place. Once oxygenated, the blood travels back to the heart’s left atrium through the pulmonary vein.

Just as the pulmonary artery is the only artery that carries deoxygenated blood, the pulmonary vein is the only vein in the body that carries oxygenated blood; in the system circuit, it is the other way around. Regardless of the kind of blood they carry, it is worded this way because veins and arteries are strictly meant to take blood to and from the heart, respectively. The blood is then passed through the one-way mitral valve into the left ventricle (“Pulmonary Circulation,” n. d. The system circuit covers a much larger area in the body than the pulmonary circuit, and is responsible for bringing the pulmonary circuit’s oxygenated blood to the capillaries and body tissue, to use their strength and function as they should. The oxygenated blood enters into the system circuit once it has been pumped out of the left ventricle into the aorta. From the aorta, the blood is distributed everywhere throughout the body except the lungs through arteries, traveling from head (carotid artery) to toe (iliac artery).

This process has the blood giving its oxygen to the tissue cells by means of the capillaries, which allow for the exchange of carbon dioxide and oxygen between the blood and tissue cells. After giving up the oxygen, the blood collects the carbon dioxide, and thus deoxygenated. As the blood continues to travel in the body, the capillaries merge together and become veins. The veins then send the carbon dioxide-rich blood back into the right atrium of the heart. (Fox, 2009) There are two ways for blood to enter the heart depending on which artery the blood has gone through.

For instance, if it has gone to one of the upper body arteries, such as the subclavian artery, the jugular vein that carries the subclavian’s deoxygenated blood only enters the heart by going through the superior vena cava, the upper body’s entry to the heart for deoxygenated blood. In the same way, the inferior vena cava is the lower body’s entry to the heart for deoxygenated blood, had the blood gone through the renal artery and renal vein, for example. In addition to the systemic circuit, there is a path that the blood can take through the mesenteric artery that allows it to pass through the hepatic portal system.

The mesenteric artery runs the blood to the gastrointestinal tract and spleen and then to the liver. The blood’s oxygen is exchanged with carbon dioxide in the capillaries of the gastrointestinal tract, but some of the blood does not take part in this exchange, and instead travels through the hepatic portal vein to the liver. The liver is particularly special, as it receives both oxygenated and deoxygenated blood. The liver then cleanses the blood of bacteria and any other harmful substance that may be in it (King, 2010).

From here, the blood flows to the hepatic vein, which is then joined into the inferior vena cava, and ultimately back to the heart. It is vital that these processes are carried out without fault. They are all important to maintaining homeostasis, and one of the ways to keep the blood flowing healthily is with exercise and a balanced diet. Proper eating and exercise are important for allowing our bodies to fight problems such as pulmonary hypertension, which an individual can get due to high blood pressure, and causes the victim to have a shortness of breath (Fagard, 1999).

In addition, studies have shown that exercise can make one’s heart twice as powerful as average and more energy efficient. The heart is made up of muscle tissue which can be trained to handle more stress, if exercised correctly (Theime, 2005). Of course, however, even if one is athlete, there are still dangers that no one can escape. Studies show that some “athletes [who] perform high-intensity physical exercise […] can potentially lead to increased risk of having arrhythmias and coronary events during competition or practice. (De Matos et al, 2011) Our bodies cannot handle too much exercise, which would only lead to unhealthy physical stress; we should allow ourselves to have a time of rest. By the same token, we cannot simply expect to be healthy without exercise, or just by eating healthily alone. As the studies mentioned would suggest, there needs to be a balance in our dietary and exercising lives. These balanced practices create stability and vitality in our internal environment as it strengthens our heart and circulatory system. This is our conscious contribution to homeostasis.