The heart and blood vessels: arteries

The idea

Arteries are vessels that carry blood away from the heart. Blood leaves the heart in surges, so artery walls are thick and contain elastic tissue that stretches and recoils, plus smooth muscle that adjusts the lumen. This maintains blood pressure and gives a pulse. The lumen is narrow relative to wall thickness, helping to keep pressure high. The aorta carries oxygenated blood to the body, while the pulmonary artery carries deoxygenated blood to the lungs, showing that 'artery' means direction, not oxygen content. Arteries branch into arterioles, which lead into capillary networks where exchange occurs.

What earns the marks

• Defines arteries as vessels carrying blood away from the heart.
• Links thick elastic tissue to stretching and recoiling as the heart pumps.
• Links muscular tissue to controlling the diameter of the lumen and hence flow.
• Explains that a narrow lumen helps maintain high blood pressure.
• Uses the aorta and pulmonary artery to show arteries do not always carry oxygenated blood.
• Describes branching of arteries into arterioles and then capillaries.

Common mistakes and how to put them right

• Claiming all arteries carry oxygenated blood.

  Put it right: The pulmonary artery carries deoxygenated blood from the heart to the lungs.

• Saying arteries have valves to stop backflow.

  Put it right: Valves are characteristic of veins, while arteries rely on elastic recoil and pressure.

• Describing the artery wall as thin.

  Put it right: Artery walls are thick and muscular with a relatively narrow lumen.

Exam tips

• Link each named feature to its effect, for example elastic tissue recoils to smooth out flow and help maintain pressure.
• If asked to compare, refer explicitly to both vessels rather than describing one in isolation.
• Use the pulmonary artery as a counterexample whenever a question implies arteries always carry oxygenated blood.