MEDICAL BIOLOGY, ANATOMY, HUMAN PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010

BIOLOGY

SECTION 1. BIOLOGICAL FOUNDATIONS OF HUMAN VITAL ACTIVITY

1.3. MOLECULAR-GENETIC AND CELLULAR LEVELS OF LIFE ORGANIZATION

1.3.2. Structural, chemical, and functional organization of eukaryotic cells

Inorganic Salts

They occur in the form of ions or solid compounds. The most important cations are K⁺, Na⁺, Ca²⁺, Mg²⁺, while the key anions are H₂PO₄^-, Cl^-, and HCO₃^-. The intracellular content of cations and anions differs significantly from their concentration in the extracellular environment. For instance, the intracellular concentration of K⁺ is very high, whereas Na⁺ is low. Conversely, the extracellular fluid (Blood) contains very little K⁺ and a relatively high amount of Na⁺.

The differential concentration of potassium and sodium ions across The Cell membrane creates an electrical potential difference between the inner and outer surfaces of The Plasma Membrane, which is essential for transmitting excitation in nerve and Muscle Tissues, as well as for the Transport of substances into the cell. The buffering Properties of the Cytoplasm—its ability to maintain a stable hydrogen ion concentration (pH)—depend on the concentration of intracellular salts. A slightly alkaline intracellular environment (pH 7.2) is thus maintained.