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Organ Systems

Cardiovascular System

The cardiovascular system is composed of the heart and blood vessels, including the arteries, veins, and capillaries.  The human heart is roughly the size of a man’s closed fist. The arteries carry oxygen-rich blood from the heart to the rest of the body while the veins carry oxygen-poor blood from the body back to the heart. The capillaries are small blood vessels where oxygen and nutrient transport occur within the systemic circuit. There are capillaries in every cell and tissue of the human body. Blood is also part of the cardiovascular system and functions by delivering oxygen and nutrients to the body while removing waste and carbon dioxide. The heart functions as a pump and is composed of the following four chambers: right atrium, right ventricle, left atrium, left ventricle. The right atrium pumps blood through the tricuspid valve to the right atrium, which pumps blood through the pulmonary artery to the lungs, where the blood is oxygenated. After the blood has been oxygenated, it flows from the lungs through the pulmonary veins and into the left atrium. The left atrium then pumps the blood through the bicuspid valve into the left ventricle, which pumps blood through the aorta and into the rest of the body, as shown below. The three layers of the heart include the epicardium, myocardium, and endocardium. The heart’s conduction system sends electrical impulses from the brain to the heart to keep it pumping on rhythm, which keeps blood circulating in the most effective way. The cardiovascular system is sometimes called the circulatory system. The best way to keep the cardiovascular system healthy is to eat a heart healthy diet high in fruits, vegetables, and whole grains and low in salt/sodium, sugar, saturated fats, and trans-fats. It is also important to maintain 40 to 60 minutes of physical exercise daily, avoid smoking and tobacco use, avoid excessive alcohol consumption, manage stress, get quality sleep, see a doctor regularly, manage all underlying conditions (hypertension, diabetes, hyperlipidemia), and maintain a healthy weight.

Diagram and Blood Flow of the Heart

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Diagram of the Circulatory System



Mayo Clinic Staff. (2019, October 26). Strategies to prevent heart disease. Mayo Clinic.

Mayo Clinic Staff. (2021, February 25). Video: Heart and circulatory system. Mayo Clinic.

Mayo Clinic Staff. (2021, February 27). Heart-healthy diet: 8 steps to prevent heart disease. Mayo Clinic.  

National Cancer Institute. (n.d.). Introduction to the cardiovascular system.

Texas Heart Institute. (2020, September 30). Anatomy of the heart and cardiovascular system.

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