Let’s follow the blood on a simple loop through the circulatory system to see how it works: Atherosclerosis can gradually make the arteries narrower, affecting the amount of blood that can flow ...

This hollow muscle is made up of four chambers: The left and right atriums make ... can human sperm survive? The rest of the circulatory system is made up of two independent networks that work ...

We refer to an integrated unit as an organ system. Groups of organ systems work together to make complete, functional organisms, like us! There are 11 major organ systems in the human body.