In this case, the damper is normally opened by the force of the spring but can be closed by the force of the motor. Removal of electrical power re-opens the damper. This style of damper is advantageous because it is fail safe; if the control to the damper fails, the damper opens and allows air to flow.
The adrenal glands, located on the top of each kidney, are responsible for releasing different hormones. Adrenal gland disorders occur when the adrenal glands produce too much or too little of these hormones.
The adrenal glands are composed of two heterogenous types of tissue. In the center is the adrenal medulla, which produces adrenaline and noradrenaline and releases them into the bloodstream, as part of the sympathetic nervous system. Surrounding the medulla is the cortex, which produces a variety of steroid hormones.