Homeostasis is a four-part dynamic process that ensures ideal conditions are maintained within living cells, in spite of constant internal and external changes. The four components of homeostasis are a change, a receptor, a control center and an effector. A healthy cell or system maintains homeostasis, also commonly referred to as “being in balance.”

Changes occur constantly in and around the cells of living systems. A change is anything that requires a cell to react, such as a change in temperature, pressure or chemical composition inside or surrounding the cell.

Once a change occurs, it’s the receptors job to detect the change and alert the proper control center to counteract it, returning the cell and the overall system to a balanced state -- homeostasis. For example, your blood pressure has risen after vigorous exercise. Receptors in certain arteries will detect the pressure increase and send impulses to the body’s control center for the cardiovascular system -- the medulla oblongata. Receptors, or nerve endings, are located in every system and tissue.

As the control center receives impulses from its remote receptors, it sends commands to the effector to counteract the change in the environment. Using the same example, the medulla oblongata commands the effector -- the heart in this case -- to slow its pulse. Control centers are located in the brain.

The effector acts on the impulses from its specific command center, counteracting the change and returning the internal and external cell environment to a balanced state. Effectors are the physical change agents such as the heart, organs and fluids of the body -- the workhorses of homeostasis.