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.
Heart valves are like one-way doors that control the direction. of blood flow between the four chambers of the heart. There are. two upper chambers (the atria) and two lower chambers (the. ventricles) (see the diagram on page 2). The atria receive blood. from the body and pump it into the ventricles.