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Which two major body systems help regulate acid-base balance in the body? Provide an example of how each of these systems accomplishes this task. Watch the video and record your response to the question using one of the following recording options.

Answer 1

The two major body systems that maintain acid-base balance of the body is the Respiratory system and the Renal system.

The respiratory system controls blood PH by changing the bodys pCO2 through regulation of respiration. The kidneys help in regulation of blood PH by excretion of H+, reabsorption of Bicarbonate, excretion of titratable acids.

This regulation occurs involving the bicarbonate- carbonic acid buffer system. [ HCO3- / H2CO3 ] The base part (HCO3-) is under the regulation of kidneys while the acid part (H2CO3) is under respiratory regulation.

Respiratory regulation of PH

The respiratory system controls blood PH by changing the bodys pCO2 through regulation of respiration. The chemoreceptors in the respiratory centre detects the changes in blood pH and control the rate of respiration and thus the rate of elimination of CO2.

For example, when there is metabolic acidosis, the respiratory system has to compensate by adjsuting the PH towards the alkalosis side. The lungs does this by increasing the respiratory rate (Hyperventillation). Now respiratory alkalosis is produced by eliminating more CO2 from the body. More CO2 eliminated means more carbonic acid (H2CO3) is eliminated, thus favouring an alkaline PH.

Renal regulation of PH

Normal urine PH is lower than that of the blood, which means that there is some amount of acidication of urine to eliminate the acids. The major mechanisms by which kidneys regulate PH are : excretion of H+, reabsorption of Bicarbonate, excretion of titratable acids.

For example, when there is Respiratory acidosis, the kidneys compensate by :-

Excretion of H+ :- Carbonic acid is ionised into H+ and bicarbonate. The H+ is then secreted into the tubular lumen and excreted and the bicarbonate is reabsorbed. So, there is net excretion of H+ and generation of HCO3-.

РСТ Plasma. Tubular lume HCO3 (Bicarbonate reaches plasma) (Htions are excreted) H, CD3 Carbonic anhydrase(CA) CO, + H20

Reabsorption if bicarbonate :- The filtered bicarbonate combines with H+ in the tubular lumen to form carbonic acid, which dissociates into CO2 and H2O. This CO2 diffuses into the cell, combining with water to form carbonic acid. This carbonic acid ionises to H+ and HCO3- .

The HCO3- is reabsorbed into the plasma, whereas the H+ in the tubular lumen combines with another HCO3-, to help in bicarbonate absorption. The net effect is reabsorption of bicarbonate without net ecretion of H+.

POT plasnya. Tubular lumes NaHCO3 (Altered) HCO, HCO3 (Bicarbonate reaches plasma) (03 HO + CO₂- - - → CO₂ + H₂O

Also, H+ is excreted as titratable acid (Sodium acid phosphate) and as ammonium ions. Here, the H+ secreted into the tubular lumen combines with NaHPO4- and NH3 to form NaH2PO4 and NH4 respectively.

So, the net effect of all these mechanisms is excretion of excess H+ (acid) from the body and reabsorption of HCO3- (alkali). Thus it can compensate for the respiratory acidosis.