Valves of the Heart. The heart functions by pumping blood both to the lungs and to the systems of the body. To prevent blood from flowing backwards or âregurgitatingâ back into the heart, a system of one-way valves are present in the heart.
An electric circuit is a path in which electrons from a voltage or current source flow. Electric current flows in a closed path called an electric circuit. The point where those electrons enter an electrical circuit is called the source of electrons.
Ground (electricity) In electrical engineering, ground or earth is the reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth. Electrical circuits may be connected to ground (earth) for several reasons.