Some older zoned systems do not use a control panel. The control panel also allows for selection of normally open or normally closed positions of the dampers for purging after the thermostats are satisfied.
Dampers come in a variety of designs.
Opposed blade dampers use a motor to open and close them. This damper design has the appearance of accordian or folding panels when closed, and metal slots when open. Single blade dampers can use a motor to open and close them, or use a spring to close them and a motor to open. This type will remain in the closed position at rest. A single blade with spring open uses the motor to close, and is open at rest.