Which of the following statement is incorrect?
1. Metabolic acid-base disorders are caused by increasing the concentration of HCO3- in the ICF.
2. Metabolic acid-base disorders are caused by the reduction of fixed acids and metabolic acids.
3. Respiratory acid-base disorders result from a mismatch between CO2 generation in peripheral tissues and CO2 excretion by the lungs.
4. In respiratory acid-base disorders, the CO2 levels of the ICF is abnormal.