In water molecule the electrons between the oxygen and the hydrogen are shared, but the sharing is not equal. Oxygen pulls electrons slightly towards itself. Therefore, the electrons are more near the oxygen, making that part of molecule(oxygen part) slightly negative. Since the electrons are not near the hydrogen so, that part of the molecule is slightly positive.
Through electrochemical processes
This would directly affect the epidermis because blisters will develop within the surface of the skin. Having blisters on the epidermis will decrease the function of the skin to be an effective barrier to disease. This is because blisters are open wounds that are prone to infection. As infection passes through these openings, it will affect the dermis and the other layers of the skin. Bullae is actually an auto-immune skin disease.
