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A structure in a vein that prevents blood flowing backwards.

Compared with veins, arteries have a narrow lumen, which helps maintain high pressure. They do not have valves along their length.

A structure that opens and closes in response to pressure differences, keeping blood flowing in one direction by preventing backflow.

Explain that pressure differences open valves and that their closure prevents backflow. Valve names are not required.

A structure in a vein that prevents blood flowing backwards.

Compared with veins, arteries have a narrow lumen, which helps maintain high pressure. They do not have valves along their length.

A structure that opens and closes in response to pressure differences, keeping blood flowing in one direction by preventing backflow.

Explain that pressure differences open valves and that their closure prevents backflow. Valve names are not required.

Valve