Electricity is generated in the body to control the nerves, organs and muscles.  The electrical signals are generated by electrochemical reactions and actions of specific types of cells.  In the heart, electrical signals control the rhythmical contraction and relaxation of the atria and ventricles, which allows the heart to pump blood throughout the body.

In this module we will explore the relationship between the electrical signals and the mechanical pumping action of the heart.  We investigate how the electrical signals are studied through measurement of the electrical potentials on the skin (electrocardiography).  We explore how these signals are interpreted by professionals such as physicians and engineers to determine whether the heart is working properly.  We also learn the principles behind engineered devices such as pacemakers and implantable defibrillators that keep people alive when there are life-threatening disturbances in normal electrical activity of the heart.