Definition: Blood vessels that carry blood from the heart to the body are called arteries, featuring thick muscular walls and high blood pressure.

Example: Capillaries function by facilitating the exchange of nutrients and oxygen between blood and surrounding tissues, with walls just one cell thick.

Highlight: Veins contain special valves to prevent blood from flowing backward, ensuring efficient return to the heart.

Definition: The 4 major blood vessels of the heart are the aorta, vena cava, pulmonary artery, and pulmonary vein.

Highlight: Which blood vessels carry blood away from the heart to the lungs? The pulmonary arteries transport deoxygenated blood to the lungs for oxygenation.

Example: What carries oxygenated blood to the heart? The pulmonary veins transport oxygen-rich blood from the lungs back to the heart's left atrium.

Definition: The circulatory system is an organ system that transports essential materials throughout the body via blood vessels and the heart.

Highlight: Coronary arteries supply the heart muscle itself with oxygen and nutrients, while pacemaker cells in the right atrium generate electrical impulses for heartbeat regulation.

Vocabulary: Pacemaker cells - specialized cardiac cells that produce electrical impulses controlling heart rhythm.