All these statements are correct about a vein EXCEPT that it

Analyze the question: We need the one statement that is NOT true of a vein. Four options are true facts about veins, and one is false.

Concept: Structure and function of veins

• Veins carry blood towards the heart.
• Blood in veins is at low pressure.
• Veins have thin walls with less muscle and elastic tissue than arteries, and a wide lumen.
• Veins have valves that prevent backflow of blood.
• Most veins carry deoxygenated blood. The pulmonary vein is the exception, which is why the word "usually" is used in option E.

Checking each option:

• A. Carries blood to the heart: True, this is the definition of a vein.
• B. Contains blood at low pressure: True.
• C. Has no valve: False. Veins do have valves, especially in the limbs, to keep blood flowing one way against gravity.
• D. Possesses fairly thick walls: Relative to capillaries, veins have walls of moderate thickness. They are thinner than arteries, but "fairly thick" is a loose description that is arguably acceptable. It is not a clear falsehood the way option C is.
• E. Usually carries deoxygenated blood: True.

Answer: The statement that is clearly incorrect is C. has no valve.

Option D is slightly debatable, since veins are thinner-walled than arteries. But the question asks for the statement that is definitely wrong, and that is C.

Exam tip: Remember "Veins have Valves", since both start with V. Arteries have thick walls and high pressure and carry blood away from the heart. Veins have thin walls and low pressure, and they carry blood back to the heart.