Lecture of buffering systems and alkaline acidosis

2021-04-15 09:55 AM

Buffer systems in the blood: Mainly carbonic acid and bicarbonate in addition to phosphates, protein, haemoglobin, carbonate.

 

Lecture of buffering systems and alkaline acidosis

Buffering system in the body

Conditioning so that the pH is in the average range of 7.35-7.45 thanks to the system of buffering in the body including:  

Buffering systems in the blood.

The cushioning role of the lungs.

The buffering role of the kidneys.

Buffering systems in the blood:

Mainly carbonic acid (H2CO3) and bicarbonate (HCO3-) in addition to phosphates (PO4), protein, hemoglobin, carbonate.

According to Henderson Hassel Bach, equation to determine the correlation between pH, PCO2, HCO3-:    

pH = 6,1 + log (HCO3/ H2CO­­­3)

HCO3- relates to alkaline reserve.

H2CO3 in plasma in the form of dissolved CO2 is directly related to CO2 / blood (PaCO2).

pH = 6,1 + log (HCO3- / PaCO­2)

The buffering role of the lungs:

Eliminate or store CO2 à H2CO3.

The buffering role of the kidneys:

Bicarbonate is retained by reabsorption due to exchange with H + ions.

Rebuilding bicarbonate: increases with acidosis and decreases with alkaline blood.

H + ion excretion: increases with acidosis and decreases with alkaline blood.

Discharge H + ions as (NH3 + H +à NH4) and absorb HCO3-.

Evaluate the alkaline condition

Medical history.

Arterial blood gas: Normal PaCO2: 35-45mmHg.

Total CO2: 24-32mEq / l.

Blood pH = pH meter (pH = 7.35-7.45).

Serum electrolytes.

Electrolytes and pH in urine.

Acidic acidosis: mainly due to changes in HCO3- and PaCO2 including:

Metabolic acidosis: due to decreased HCO3- or fixed acid accumulation (insoluble, non-volatile), pH decreased in response to compensate through the lungs by increasing ventilation  PaCO2 â .

Blood alkaline metabolism: Do HCO3- increase, pH increase offset through the lungs respond by reducing aeration à PaCO2.

Respiratory acidosis blood: Do PaCO2 was stagnant in the lungs leads to PaCO2 , pH â offset by increased absorption of HCO3- kidneys and produce HCO-3.

Respiratory alkalosis: Due to increased ventilation, the Paco2 â compensated pH is eliminated through the kidneys by excreting HCO-3 and reducing renal regeneration.