The primary chemical buffer in human blood is the carbon dioxide by carbonate ion. Recall the components of a buffer are weak acid and its conjugate base. The buffer in blood is commonly presented as the carbon dioxide as the weak acid and by carbonate as its conjugate weak base. The carbon dioxide is controlled by the lungs and the conjugate base, the bicarbonate is controlled by the kidneys. If there's an increase in CO2, that will cause an increase in hydrogen ion concentration, creating a acidic environment. If there's a decrease in CO2, that will reduce the amount of hydrogen ion. Therefore, creating an alkaline or basic environment, the kidneys will control the bicarbonate ion which will also affect the pH. If there's an increase in bicarbonate ion, that will cause a drop in H+. A drop in H+. will create an alkaline or basic environment, therefore a higher pH. If there is a decrease in the bicarbonate ion, that will create an increase in hydrogen ion concentration, the pH will decrease. The change in pH with the change in hydrogen ion concentration is represented by this equation, pH equals the negative of a i to the H+. If the hydrogen ion concentration increases, the pH will drop. The hydrogen ion concentration decreases, the pH will increase. There are four abnormal pH conditions that are associated with the blood buffer. Respiratory acidosis, respiratory alkalosis, metabolic acidosis, metabolic alkalosis. We will look at each one of these conditions in detail. The first one is respiratory acidosis. This is where there's too much carbon dioxide in the lungs. The lungs are retaining too much carbon dioxide, therefore the pressure of the carbon dioxide increases. As we said before, there's too much CO2 or the weak acid that will increase the hydrogen ion concentration, therefore decreasing the pH. The second condition is respiratory alkalosis. This is where the lungs remove too much carbon dioxide from the blood, therefore the pressure of the carbon dioxide in the lungs decreases. If there's a reduced amount of acid that will cause a reduction in the hydrogen ion concentration, which will cause the pH to go up creating an alkaline condition. The third of normal condition is metabolic acidosis. This is where the kidneys cause a drop in the bicarbonate ion. If there's a drop in the base, the bicarbonate ion, there will be an increase in the hydrogen ion concentration creating an acidic environment, therefore pH will drop. The fourth of normal condition is metabolic alkalosis. This is where the kidneys cause an increase in the bicarbonate ion. An increase in the bicarbonate ion on the base causes a decrease in a hydrogen ion concentration, which creates a basic or alkaline environment, therefore the pH will increase.