The proton motive force (pmf) is driven by the proton motive force (pmf) is driven by the pumping of protons through the plasma membrane the pumping of electrons though the plasma membrane the difference in charge across the plasma membrane with protons outside the membrane the difference in charge across the plasma membrane with electrons outside the membrane

 When a cell membrane becomes energized due to electron transport reactions by the electron carriers embedded in it then this results in proton motive force (PMF). This way the cell becomes a tiny battery. 
The proton motive force (PMF) is driven by the difference in charge across the plasma membrane with protons outside the membrane.

The most numerous cells in the lungs are dust cells, also known by their scientific term of alveolar marcrophages.
These cells are located in any person's lungs and are responsible for keeping your lungs and air pipes clean of any dust particles and other materials that may harm your body. Their role is to destroy any foreign substances, such as bacteria and others.