Structure and function of veins.

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Explain the structure of veins compared to arteries.

Veins have thinner walls than arteries, this is because walls of veins do not have to withstand high blood pressure

Veins have a larger lumen, carry a greater volume of blood compared to arteries.

Smooth muscle layer and elastic layer are also thinner in veins compared to arteries

Whats an important adaptation of veins.

Veins contain valves, they help to keep the blood moving in the forward direction.

When skeletal muscles such as arms and legs contract, they squeeze veins lying between them , and when squeezed, due to thin walls , they change shape.

The squeezing forces blood along, and if the blood moves forward, the valves remain open, if blood moves backwards then the valves shut.

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