Electrolytes

These are solutions of substances that, when dissolved or melted, break down (disassociate) into ions. The osmotic pressure of electrolyte solutions is higher than that of non-electrolyte solutions of the same molar concentration. Electrolytic dissociation is a process during which electrolytes, influenced by polar solvent molecules, break down (disassociate) into ions. This phenomenon is often called ionization. Electrolytes are divided into strong and weak ones. Strong electrolytes completely break down (disassociate), while weak electrolytes poorly break down (disassociate) into ions even in dilute solutions. Ions carrying a positive or negative charge (anions and cations) are present in all body fluids and liquid components.

The distribution of electrolytes in the body fluids differs in both qualitative and quantitative composition. Na⁺ – is the main extracellular cation, while K⁺ – is the main intracellular cation. Inside the cell, protein and phosphate anions prevail, while in the extracellular fluid – chlorides (Cl^–) and acid carbonates (HCO^–₃). The diversity of ionic composition in cells and surrounding fluids is vital for the organism. It is maintained by ionic pumps located in the cell membranes.

Despite the diversity of ion composition, the osmotic activity inside the cell and in the extracellular fluid is almost the same. Sodium is the main cation in plasma, accounting for up to 93% of their total amount, while chlorides and acid carbonates belong to anions. The sum of anions and cations is almost equal, i.e., the system is electroneutral.

An increase in aldosterone production leads to hypokalemia. More potassium is excreted in the urine, while sodium is retained in the tissues.

Hypokalemia affects the heart function.

Source | Glossary of Most Commonly Used Biomedical Terms and Concepts | Lithuanian University of Health Sciences | Academician Professor Antanas Praškevičius, Professor Laima Ivanovienė