Blood PH: How To Measure? What Is The Norm?

2024 Author: Josephine Shorter | [email protected]. Last modified: 2023-12-16 21:43

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

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

Its values are normally in the range from 7.36 to 7.44, usually 7.4 units.

Displacement of indicators towards the alkaline side (alkalosis), or towards acidity (acidosis) are 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 the death of the organism.

Content:

• Acid-base balance: what is it?
• How the systems work
• pH of different human blood systems
• Acidosis, blood alkalosis

Acid-base balance: what is it?

It would seem that the entry into the digestive tract, and further into the blood, products with an acidic or alkaline reaction should change the composition of the blood. In fact, the body's buffer systems ensure the stability of the acid-base balance, preventing fluctuations outside the safe range.

List of buffer systems:

• Bicarbonate (hydrocarbonate) system - provides at least 50% of the adaptive capabilities 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 body, prevent the shift of acid-base balance in any direction, despite the fact that the body consumes foods of various compositions. Buffer systems have an inexhaustible margin of safety, since 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 the systems work

Basic hydrocarbonate system

The hydrocarbonate system includes two components: H2CO3 and NaHCO3. Chemical reactions constantly occur between them and the acids and alkalis entering the bloodstream.

Strong alkali reaction:

NaOH + H2CO3 → NaHCO3 + H2O

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

The acid is neutralized as follows:

HCl + NaHCO3 → NaCl + H2CO3

The reaction produces carbon dioxide, which is carried by the lungs into the environment.

The bicarbonate buffering system is most sensitive to pH changes and therefore reacts immediately.

Hemoglobin, protein and phosphate systems of the blood

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

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

NaOH + HHb → NaHb + H2O

The interaction of hemoglobin when acid enters the blood:

HCl + NaHb → NaCl + HHb

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

The phosphate buffer system maintains the acid-base balance in urine, in the intercellular fluid, and in the cytoplasm of the cell.

pH of different human blood systems

The acid-base index of oxygenated arterial blood is 0.01-0.02 units higher than the same index of venous blood, which contains carbon dioxide in excess.

The acidity of blood plasma, which has a balance of hydrogen ions and hydroxyl 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 hemostatic system is devoid of fibrinogen. Its acidity is of practical importance when plasma is used to determine the blood group using hemaglutinating sera.

Blood acidosis and alkalosis

The shift of the hydrogen balance to the acidic or alkaline side can be compensated and uncompensated. It is determined by the alkaline reservoir - the volume of carbon dioxide displaced by a strong acid from 100 ml of plasma. The rate of this indicator is 50-70 ml of CO ₂.

• CO ₂ below 45 ml - uncompensated acidosis;
• CO ₂ above 70 ml - alkalosis.

Alkalosis types:

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

Types of acidosis:

• Gas - provoked by the slow release of CO _{2 from the} lungs, goes into hypercapnia;
• Non-gas (alimentary) - occurs with the accumulation of metabolic products, when they come from the digestive tract;
• Primary renal - occurs when there is a violation of reosorption in the renal tubules, accompanied by a loss of alkali.

With a significant deviation of the pH value from the norm, qualified medical assistance is required. When he is in the limit values of the range, with a satisfactory state of health, it is important for the patient himself to pay attention to his state of health.

The main causes of pH disturbances are the use of “harmful” foods, alcohol, and smoking. If the patient does not possess information, he will not pay attention to his health until he is in a state of acute pathology.

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

To maintain the indicator within the normal range, adherence to the rules of a healthy diet, regimen, and the implementation of recreational activities are required.

Author of the article: Alekseeva Maria Yurievna | Therapist

Education: From 2010 to 2016 Practitioner of the therapeutic hospital of the central medical-sanitary unit No. 21, city of elektrostal. Since 2016 she has been working in the diagnostic center No. 3.