Enzymes, cytochromes, hemoglobin and others – all functional proteins are abundant in hydrogen bonds. Because of this, they are highly influenced by the concentration of hydrogen in their environment.
The normal pH varies depending on the body fluid being examined but not by a wide margin. When talking about arterial blood, the normal pH is 7.4; when talking about venous blood and IF, the normal pH is 7.35. When the pH levels in the cells and venous blood decreases, great amounts of carbon dioxide and acidic metabolites can be found. These then combines with water, giving rise to carbonic acid.
During instances where the pH level of arterial blood rises above 7.45, a condition known as alkalosis or alkalemia occurs. On the contrary, when pH levels of arterial blood goes below 7.35, a condition known as acidosis or acidemia occurs. Putting sense into theory, the midline number in the pH stretch is 7.0, hence it is neutral.
Sources of Acids and Base
The body gets small amounts of acidic substances by the food we eat. The majority of hydrogen ions come from byproducts of metabolism or metabolic end products. Take for example the presence of phosphoric acid in the ECF. This is due to the breakdown of proteins containing phosphorus, liberating phosphoric acid and entering the ECF. Also, during anaerobic respiration, lactic acid is produced. In the course of fat metabolism, it yields various organic acids such as ketone bodies and fatty acids. During the exchange of nutrients and loading of carbon dioxide, hydrogen ions are liberated.
Chemical Buffer System
Let us first put into consideration, in order to better understand things, that the acidic of a solution is dependent on the amount of free hydrogen ions, not with the ones bound to anions. With this premise, we can then be able to understand the concept of strong and weak acids. Strong acids can completely dissociate and liberate all hydrogen ions in water. Weak acids on the other hand can only partially dissociate hydrogen ions. It can be inferred that strong acids can dramatically change the pH level of a solution and that weak acids have a subtle effect on the pH level but this feature is important when talking about buffer systems.
Bicarbonate Buffer System
The only important ECF buffer is the bicarbonate buffer system. It is composed of carbonic acid and sodium bicarbonate. Take note that carbonic acid is a weak acid and does not completely liberate all hydrogen ions. When for example HCl, a strong acid, is introduced into the system, the weak carbonic acid remains intact. However, the present bicarbonate ions of the salt functions s a weak base that ties up the hydrogen ions liberated from HCl, a stronger acid, thus forming more carbonic acid.
Phosphate Buffer System
The phosphate buffer system is like a mirror image of the bicarbonate buffer system. The phosphate buffer system is made up of dihydrogen phosphate and monohydrogen phosphate. The same thing happens with the bicarbonate buffer system.
Protein Buffer System
The abundant proteins found in the plasma and in the cells are considered the most powerful and plentiful source of buffers and to attest to that, almost ¾ of all the buffering power of the body fluids resides in the cells and it reflects the buffering activity of intracellular proteins.