the human heart is just an 10 once pump that can deliver blood at a capacity of 300lit/hour ... the SA node giving energy to the heart muscles to pump blood ...

this SA node does this purely on the basis of electrostatic charges...

The coronary artery supplies blood to the muscles of heart .... the blockage in this coronary artery can induce heart attack ...




to get more info about this ....check out on ...

http://health.howstuffworks.com/heart.htm