The relationship between acids and bases is of great significance to the functioning of all metabolic processes in the organism. A balance between acids and bases is necessary to normal metabolism. This balance is decisive to the structuring and function of proteins, the permeability of membranes, the distribution of electrolytes and the functioning of the connective tissue. The pH level of the blood and of the external and internal cellular spaces must be kept constant under all circumstances within a small range of fluctuation, so that the many different processes in our bodies can be carried out in a controlled way. Different buffer systems (regulatory systems, which compensate for the excess acid or base), which are constantly put into action according to the current strain of acids or bases on the organism, are available to do this.