Basic Anatomy of the Heart
About the heart
The heart is the hardest working muscle in the human body. The heart is located almost
in the center of the chest. The adult human heart is about the size of a fist.
The heart beats at an average rate of 80 times a minute. That's about 115,000 times
in one day, or about 42 million times in a year. In a 70-year lifetime, an average
human heart will beat more than 2.5 billion times. The heart works hard even when
you are at rest.
The average heart rate for children 10 years and older and adults is 60 to 100 beats
per minute. In a well-trained athlete, the heart rate can be healthy at a rate of
40 to 60 beats per minute.
How the heart works
The cardiovascular system is made up of the heart and blood vessels. Its job is to
circulate blood throughout your body. The blood brings oxygen and nutrients to the
The heart is made up of:
4 chambers (2 atria and 2 ventricles) that get blue (deoxygenated) blood from the
body. They pump out red (oxygen-rich) blood back to it:
Blood vessels that include a network of arteries and veins that carry blood throughout
4 valves to prevent backward flow of blood:
An electrical system that serves as a natural pacemaker. It also conducts electricity
to stimulate the heart muscles to contract. This controls the rate and rhythm of the