Human blood is weakly alkaline. Because human blood contains a variety of buffer substances, including bicarbonate and carbonate, when there are acidic or alkaline substances into the blood, the buffer substances in the plasma can effectively reduce the impact of acidic or alkaline substances on the pH value of the blood, and the pH value can be maintained at 7.35~7.45, keeping a relatively constant change. 1. If the blood pH value is too high or too low, it will have certain damage to the human body. An increase in blood pH value suggests that the human body is experiencing uncompensated alkalosis, and the main types are respiratory alkalosis and metabolic alkalosis. 2. Decrease in blood pH, respiratory acidosis and metabolic acidosis, respiratory acidosis will appear respiratory muscle paralysis, can be seen in obstructive pulmonary disease, occupational asthma, diabetic ketoacidosis and renal excretory disorders, and so on.