Blood pH: how to measure? What is the norm?

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Blood pH: how to measure? What is the norm?
Blood pH: how to measure? What is the norm?
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blood pH: what is the norm and how to measure it?

Hydrogen indicator, which determines the acidity of the blood, or pH, or a marker of acid-base balance, is a constant value.

It normally ranges from 7.36 to 7.44, usually 7.4 units.

Shift in indicators towards the alkaline side (alkalosis), or towards acidity (acidosis) - symptoms of trouble that require urgent treatment.

If the pH drops below 7 units, or rises above 7.8 units, a person is in a borderline state between life and death, where 6.8 on the one hand, and 8.0 units from the opposite segment of the range mean death organism.

blood pH
blood pH

Acid-base balance: what is it?

Acid-base balance
Acid-base balance

It would seem that the intake of products with an acidic or alkaline reaction into the digestive tract, and further into the blood, should change the composition of the blood. In fact, the buffer systems of the body ensure the stability of the acid-base balance, not allowing fluctuations beyond the safe range.

List of buffer systems:

  • Bicarbonate (hydrocarbonate) system - provides at least 50% of the adaptive abilities of the hemostasis system;
  • Hemoglobin system - 35% safety;
  • Blood protein system - 10% buffer capacity;
  • Phosphate system - 5-6% buffer safety.

These systems, supporting the vital activity of the organism, prevent the shift of the acid-base balance in any direction, despite the fact that the body consumes products of various composition. Buffer systems have an inexhaustible margin of safety, as they are constantly supported by the excretory system, which is activated at the level of reflexes when it is necessary to remove metabolic products.

How systems work

Main hydrocarbon system

Basic hydrocarbon system
Basic hydrocarbon system

Hydrocarbonate system includes two components: H2CO3 and NaHCO3. Chemical reactions are constantly taking place between them and the acids and alkalis entering the bloodstream.

Reaction with strong alkali:

NaOH + H2CO3 → NaHCO3 + H2O

The sodium bicarbonate formed as a result of this interaction is soon excreted by the urinary system.

Neutralization of the incoming acid occurs as follows:

HCl + NaHCO3 → NaCl + H2CO3

As a result of the reaction, carbon dioxide is produced, which is excreted by the lungs into the environment.

The bicarbonate buffer system is most sensitive to changes in pH, so it responds immediately.

Hemoglobin, protein and phosphate systems of blood

Blood hemoglobin, with the help of red pigment, reacts to changes in acidity by binding oxygen, or giving it to the surrounding tissues. The acidity of the red pigment hemoglobin changes by 0.15 units, acting as a neutral s alt or a weak acid, depending on the circumstances.

The reaction of hemoglobin when an alkaline base enters the blood:

NaOH + HHb → NaHb + H2O

Interaction of hemoglobin when acid enters the blood:

HCl + NaHb → NaCl + HHb

The protein buffer system is involved in maintaining pH balance depending on the concentration and structure of protein compounds.

Phosphate safety buffer system maintains the acid-base balance in the urine, in the interstitial fluid, in the cytoplasm of the cell.

pH of different human blood systems

The acid-base value of oxygenated arterial blood is 0.01-0.02 units higher than that of venous blood containing carbon dioxide in excess.

The acidity of blood plasma, which has a balance of hydrogen ions and hydroxide ions, corresponds to the acidity of the blood as a whole.

The pH of other media (serum) may have a small range of values. Blood plasma withdrawn from the hemostasis system is devoid of fibrinogen. Its acidity is of practical importance when plasma is used for blood typing using hemagglutinating sera.

Acidosis and blood alkalosis

Acidosis
Acidosis

Shift of the hydrogen balance to the acidic or alkaline side can be compensated and uncompensated. It is determined by the alkaline reserve - the volume of carbon dioxide displaced by a strong acid from 100 ml of plasma. The norm of this indicator is 50-70 ml CO2.

  • CO2 below 45 ml - uncompensated acidosis;
  • CO2above 70 ml – alkalosis.

Types of alkalosis:

  • Gas - occurs with altitude sickness, with hyperventilation of the lungs, provoked by increased release of carbon dioxide by the lungs, turns into hypocapnia;
  • Non-gas - a distinction is made between alimentary alkalosis from food and metabolic alkalosis associated with changes in metabolism.

Types of acidosis:

  • Gas - provoked by delayed recoil of CO2 lungs, turns into hypercapnia;
  • Non-gas (alimentary) - occurs when metabolic products accumulate, when they enter from the gastrointestinal tract;
  • Primary renal - occurs when there is a violation of resorption in the renal tubules, accompanied by a loss of alkalis.

With a significant deviation of the hydrogen index from the norm, qualified medical assistance is required. When he stays in the extreme values of the range, with a satisfactory state of he alth, it is important for the patient himself to pay attention to the state of his he alth.

The main causes of pH disturbance are the use of "harmful" foods, alcohol, and smoking. If the patient does not have information, he will not pay attention to his he alth until he is in a state of acute pathology.

You can normalize the acid-base balance with the help of dietary nutrition, but when the old lifestyle returns, the pH values will return to their previous values.

To maintain the indicator within the normal range, it is required to follow the rules of a he althy diet, regimen, and the implementation of recreational activities.

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