Structure of the Heart 

The heart is a muscular organ, about the size of the fist, of the same person.  It is located slightly to the left of the chest and is responsible for the continuous circulation of blood in the cardiac cycle around the whole body.  It is a myogenic structure which means it can develop a contraction from within itself without external stimulation. An adult human heart weighs between 200 and 425 grams and on average, a person’s heart will beat 100,000 times a day, pumping approximately 7,600 litres of blood.

 Image showing the structure of the heart, its main vessels, chambers and valves 

Image created by Wapcaplet in Sodipodi, cropped and reduced in the GIMP. (created by Wapcaplet) [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons