The heart is a pump, and the blood goes round, and round, and round all the time. And why does it do that? Why can't it just have a rest? Well, the blood has to be kept moving around all the time ...

Well-known industry author and instructor Jim Johnson is offering a new video for technicians who want to sharpen their troubleshooting skills. "This HVAC training video program, is available in DVD ...

Narrator: Well here we are ladies and gentlemen, in the heart, the powerhouse of the circulatory system, the hardest working muscle in the entire human body! Your heart first pumps blood to your lungs ...

A schematic diagram for the three constituent parts of Earth system science and their functional elements A schematic diagram for the behavior of physical, chemical and biological interactions within ...