The Cardiovascular System

Front

Cardiovascular System Noun

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[kar-dee-oh-vas-kyuh-ler sis-tuhm]

Back

Cardiovascular System

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The organ system that circulates blood to deliver oxygen and nutrients and remove waste products from the body's cells.

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Example: This diagram shows the cardiovascular system, a network of blood vessels (arteries in red, veins in blue) and the heart, which circulates blood throughout the body.

Front

Heart Noun

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[hart]

Back

Heart

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The muscular organ responsible for pumping blood through the blood vessels of the circulatory system by repeated, rhythmic contractions.

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Example: This diagram shows a cross-section of the human heart, labeling its four main chambers and the major blood vessels connected to it.

Front

Atria Noun

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[ey-tree-uh]

Back

Atria

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The two upper chambers of the heart that receive deoxygenated blood from the body and oxygenated blood from the lungs.

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Example: This diagram shows a cutaway of the heart, labeling the two upper chambers: the right atrium and the left atrium, which receive blood.

Front

Ventricles Noun

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[ven-tri-kuhls]

Back

Ventricles

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The two lower chambers of the heart that are responsible for pumping blood out to the lungs and the body.

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Example: This diagram shows the heart's four chambers, clearly labeling the two lower chambers as the right and left ventricles, which pump blood.

Front

Septum Noun

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[sep-tuhm]

Back

Septum

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The wall of tissue that divides the heart vertically, separating the right and left atria and ventricles from each other.

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Example: The septum is the muscular wall that divides the heart into a right side and a left side, preventing oxygen-poor and oxygen-rich blood from mixing.

Front

Pericardium Noun

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[per-i-kahr-dee-uhm]

Back

Pericardium

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The double-layered sac that forms the outer layer of the heart, enclosing it and the roots of the great vessels.

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Example: This diagram shows the pericardium, a sac that encloses the heart, and identifies its two layers and the fluid-filled space between them.

Front

Myocardium Noun

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[mahy-oh-kahr-dee-uhm]

Back

Myocardium

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The middle, muscular layer of the heart wall, composed of cardiac muscle tissue responsible for the heart's pumping action.

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Example: This diagram shows a magnified view of the heart's muscular wall (myocardium), revealing its special branched, striated cells connected by intercalated discs.

Front

Endocardium Noun

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[en-doh-kahr-dee-uhm]

Back

Endocardium

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The thin, smooth membrane that forms the innermost layer, lining the chambers of the heart and covering its valves.

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Example: This diagram shows a cross-section of the heart and a magnified view of its wall, identifying the Endocardium as the innermost layer.

Front

Epicardium Noun

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[ep-i-kahr-dee-uhm]

Back

Epicardium

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The uppermost, visceral layer of the pericardium that covers the external surface of the heart muscle.

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Example: This diagram shows a cross-section of the heart wall, highlighting the epicardium as the outermost layer, located just inside the pericardial cavity.

Front

Atrioventricular Valves Noun

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[ey-tree-oh-ven-trik-yuh-ler valvs]

Back

Atrioventricular Valves

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The heart valves located between the atria and the ventricles that prevent the backflow of blood into the atria.

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Example: This diagram shows the atrioventricular valves (tricuspid and mitral) located between the atria and ventricles, controlling one-way blood flow through the heart.