2.65 describe the structure of arteries, veins and capillaries and understand their rol

Arteries:

-        Blood flows away from the heart

-        Delivers blood to organs

-        Thick muscles and walls

-        Small opening (lumen)

Veins:

-        Blood flows towards the heart

-        Blood returns from the organ

-        Thin walls

-        Large opening

Capillaries:

-        For gas exchange and food transport

-        Oxygen and food enters, carbon dioxide leaves

-        Walls are one cell thick for faster diffusion

-        Can only fit one cell