Question

- veins are then wolled and have values justify ​

Answer 1

Answer:

Veins are thin-walled and have valves that prevent the blood from flowing back in the wrong direction. Veins carry blood heading toward the heart. Blood coming from the tissues has delivered O2 and picked up CO2 from the cells

Answer 2

Explanation:

Veins have thin walls because the blood there is no longer under pressure and they have valves to ensure blood flow in one direction.