TOPIC 1.CLASSIFICATION KINGDOM FUNGI

Veins have a larger lumen and less muscular walls compared to arteries. This is because the blood in the veins flows at low pressure.

Vein have valves at regular intervals. The valves prevent the back flow of blood.

 

The muscles next to the veins squeeze the veins and help to force blood to flow towards the heart. The contraction of the ribs during breathing also helps to squeeze some veins and keep blood flowing.

Capillaries

Capillaries are the smallest blood vessels. They are narrow and have walls that are one cell thick