Federal employees are compensated according to government-regulated pay scales. More than 70 percent of federal employees are paid according to the most common pay scale, the General Schedule (GS) , but there are a variety of alternative pay schedules as well.
Four heart valves control the flow of blood through the heart. They act as one-way doors, opening to let blood exit or enter a chamber, then closing to keep blood from flowing backward. 1  The tricuspid valve controls blood flow from the right atrium to the right ventricle.
Updated August 29, 2016. There are four heart valves in a healthy human heart. The valves help to maintain proper blood flow through the heart, keeping blood moving efficiently and smoothly, and in the right direction. In addition to the valves there are four heart chambers -- the upper chambers are called the left and right atrium, the lower chambers are the left and right ventricle. A healthy heart valve will stop blood from flowing out of a heart chamber until it is time for the heart to pump the blood to its next destination.