That means that the vans are very busy indeed, all the time. So it's a good job we've got the circulatory system to transport nutrients, water and oxygen to the entire body. Your circulatory ...

This short film offers a look at respiration and a tour around the circulatory system and digestive system in the human body, through blood vessels and into mitochondria. There is a detailed ...

Veins between two capillary networks are portal systems. Closed circulatory system, but fluid constituents of blood leak out of capillaries and return to the heart by the second component of the ...