Which structural feature of veins is most relevant to venipuncture technique?

Giải thích

Veins have thin walls and one-way valves that keep blood moving toward the heart, which is why a large vacuum tube or aggressive suction can collapse them and why needles are inserted pointing toward the heart away from valves. Arteries, not veins, have thick muscular walls and a palpable pulse. Arteries carry blood away from the heart while veins return it.