The Heart

Front

Pericardium Noun

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[per-i-kahr-dee-uhm]

Back

Pericardium

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A double-walled sac or membrane that surrounds the heart, providing protection and anchoring it within the chest cavity.

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Example: This diagram shows the pericardium is a protective sac around the heart, with two layers (parietal and visceral) and fluid in between.

Front

Myocardium Noun

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[my-oh-kahr-dee-uhm]

Back

Myocardium

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The muscular tissue layer of the heart wall, which is the thickest layer responsible for the heart's pumping action.

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Example: This image shows that the myocardium (heart muscle) is made of special, interconnected cardiac muscle cells, which have features like striations and a nucleus.

Front

Atrium Noun

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[ey-tree-uhm]

Back

Atrium

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An upper chamber of the heart that functions as a receiving area for blood returning from the body or lungs.

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Example: This diagram shows the heart's two upper chambers, the right and left atrium, which are responsible for receiving blood before it enters the ventricles.

Front

Ventricle Noun

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[ven-tri-kuhl]

Back

Ventricle

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A lower, thick-walled chamber of the heart that forcefully pumps blood out to the lungs or the rest of the body.

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Example: This diagram shows the heart's two lower chambers, the right and left ventricles, which are responsible for pumping blood out of the heart.

Front

Septum Noun

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[sep-tuhm]

Back

Septum

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The muscular wall of tissue that divides the right and left sides of the heart, preventing blood from mixing.

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

Front

Artery Noun

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[ahr-tuh-ree]

Back

Artery

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A type of blood vessel that carries blood away from the heart to the body's tissues, typically under high pressure.

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Example: This image shows a cross-section of an artery, revealing its thick, muscular, and layered walls which allow it to withstand high-pressure blood flow.

Front

Vein Noun

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[veyn]

Back

Vein

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A blood vessel that carries blood from the body's tissues back toward the heart, often containing one-way valves.

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Example: This diagram shows veins (in blue) as the blood vessels that collect blood from all over the body and carry it back to the heart.

Front

Capillary Noun

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[kap-i-ler-ee]

Back

Capillary

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The smallest type of blood vessel where the vital exchange of oxygen, nutrients, and waste products occurs with tissues.

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Example: An artery branches into a network of tiny capillaries, where gas exchange occurs, before collecting into a vein to carry blood away from the tissues.

Front

Aorta Noun

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[ey-awr-tuh]

Back

Aorta

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The largest artery in the body, originating from the left ventricle and distributing oxygenated blood to the entire systemic circulation.

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Example: This diagram shows the aorta as the largest artery (in red) carrying oxygen-rich blood from the heart's left ventricle to the rest of the body.

Front

Vena Cava Noun

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[vee-nuh key-vuh]

Back

Vena Cava

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The two large veins, superior and inferior, that return deoxygenated blood from the body into the heart's right atrium.

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Example: This diagram shows the heart's chambers and major vessels, but it does not label the Vena Cava, the large blue vein returning blood to the right atrium.